BRITISH AEROSPACE HOLDINGS INC
SC 13D, 1997-02-10
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                                  UNITED STATES

                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                                  SCHEDULE 13D

                    Under the Securities Exchange Act of 1934

                                (Amendment No. )*

                          ORION NETWORK SYSTEMS, INC.
                          ---------------------------
                               (Name of Issuer)
                                       
                    Common Stock, par value $.01 per share
                    --------------------------------------
                        (Title of Class of Securities)
                                       
                                   68628K104
                                   ---------
                                (CUSIP Number)

                              Charles E. Gaba, Esq.
                        British Aerospace Holdings, Inc.
                          15000 Conference Center Drive
                            Chantilly, Virginia 20151

                                (703) 227-1510
                    --------------------------------------
                 (Name, Address and Telephone Number of Person
                Authorized to Receive Notices and Communications)

                               January 31, 1997
                    --------------------------------------
                     (Date of Event which Requires Filing
                              of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition which is the subject of this Schedule 13D, and is filing this
schedule because of Rule 13d-1 (b)(3) or (4), check the following box |_|.

Note: Six copies of this statement, including all exhibits, should be filed with
the Commission. See Rule 13d-1(a) for other parties to whom copies are to be
sent.

*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter disclosure
provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).


<PAGE>

                                  SCHEDULE 13D

CUSIP No. 68628K104                                        Page 2 of _____ Pages
          ---------                                      

1        Name of Reporting Person
         S.S. or I.R.S. Identification Nos. of Above Person

                  British Aerospace Holdings, Inc.

2        Check the Appropriate Box If a Member of a Group*

                                     a. |_|

                                     b. |_|

3        SEC Use Only

4        Source of Funds*           WC

5        Check box if disclosure of legal proceedings is required pursuant to
         item 2(d) or 2(e)           |_|

6        Citizenship or Place of Organization

                  Delaware

                           7        Sole Voting Power

  Number of
   Shares

Beneficially               8        Shared Voting Power
  Owned By                                  7,138,096

    Each

  Reporting                9        Sole Dispositive Power
   Person

    With

                           10       Shared Dispositive Power
                                            7,138,096

11       Aggregate Amount Beneficially Owned by Each Reporting Person

                                            7,138,096

12       Check Box If the Aggregate Amount in Row (11) Excludes Certain Shares*
                                    |_|

13       Percent of Class Represented By Amount in Row (11)

                                            40.7%

14       Type of Reporting Person*

                                            CO

                      *SEE INSTRUCTIONS BEFORE FILLING OUT!

<PAGE>

                                  SCHEDULE 13D

CUSIP No. 68628K104                                        Page 3 of _____ Pages
          ---------                                      


1        Name of Reporting Person
         S.S. or I.R.S. Identification No. of Above Person

                  British Aerospace Plc

2        Check the Appropriate Box If a Member of a Group*

                                     a. |_|

                                     b. |_|

3        SEC Use Only

4        Source of Funds*

                                    N\A

5        Check box if disclosure of legal proceedings is required pursuant to
         item 2(d) or 2(e)           |_|

6        Citizenship or Place of Organization

                  England and Wales

                           7        Sole Voting Power

  Number of
   Shares

Beneficially               8        Shared Voting Power
  Owned By                                  7,138,096

    Each

  Reporting                9        Sole Dispositive Power
   Person

    With

                           10       Shared Dispositive Power
                                            7,138,096

11       Aggregate Amount Beneficially Owned by Each Reporting Person

                                            7,138,096

12       Check Box If the Aggregate Amount in Row (11) Excludes Certain Shares*
                                    |_|

13       Percent of Class Represented By Amount in Row (11)

                                            40.7%

14       Type of Reporting Person*

                                            CO, HC

                      *SEE INSTRUCTIONS BEFORE FILLING OUT!

<PAGE>

                                  SCHEDULE 13D

CUSIP No. 68628K104                                        Page 4 of _____ Pages
          ---------                                        


1        Name of Reporting Person
         S.S. or I.R.S. Identification No. of Above Person

                  British Aerospace Communications, Inc.

2        Check the Appropriate Box If a Member of a Group*

                                     a. |_|

                                     b. |_|

3        SEC Use Only

4        Source of Funds*

                                            WC

5        Check box if disclosure of legal proceedings is required pursuant to
         item 2(d) or 2(e)           |_|

6        Citizenship or Place of Organization

                  Delaware

                           7        Sole Voting Power

  Number of
   Shares

Beneficially               8        Shared Voting Power
  Owned By                                  3,094,276

    Each

  Reporting                9        Sole Dispositive Power
   Person

    With

                           10       Shared Dispositive Power
                                            3,094,276

11       Aggregate Amount Beneficially Owned by Each Reporting Person

                                            3,094,276

12       Check Box If the Aggregate Amount in Row (11) Excludes Certain Shares*
                                    |_|

13       Percent of Class Represented By Amount in Row (11)

                                            17.6%

14       Type of Reporting Person*

                                            CO

                      *SEE INSTRUCTIONS BEFORE FILLING OUT!

<PAGE>

                                  SCHEDULE 13D

CUSIP No.68628K104                                         Page 5 of _____ Pages
         ---------                                         

1        Name of Reporting Person
         S.S. or I.R.S. Identification No. of Above Person

                  British Aerospace Satellite Investments, Inc.

2        Check the Appropriate Box If a Member of a Group*

                                     a. |_|

                                     b. |_|

3        SEC Use Only

4        Source of Funds*

                                    N\A

5        Check box if disclosure of legal proceedings is required pursuant to
         item 2(d) or 2(e)           |_|

6        Citizenship or Place of Organization

                  Delaware

                           7        Sole Voting Power

  Number of
   Shares

Beneficially               8        Shared Voting Power
  Owned By                                  472,391

    Each

  Reporting                9        Sole Dispositive Power
   Person

    With

                           10       Shared Dispositive Power
                                            472,391

11       Aggregate Amount Beneficially Owned by Each Reporting Person

                                            472,391

12       Check Box If the Aggregate Amount in Row (11) Excludes Certain Shares*
                                    |_|

13       Percent of Class Represented By Amount in Row (11)

                                            2.7%

14       Type of Reporting Person*

                                            CO

                      *SEE INSTRUCTIONS BEFORE FILLING OUT!

<PAGE>



Item 1.  Security and Issuer

         (a)      Title of Class of Securities

                  common stock, par value $.01 per share ("Common Stock")

         (b)      Name of Issuer

                  ORION NETWORK SYSTEMS, INC. (the "Issuer")

         (c)      Address of Issuer's Principal Executive Offices

                  2440 Research Boulevard, Suite 400
                  Rockville, MD 20850

Item 2.  Identity and Background

                  This statement of beneficial ownership interest is being
filed by the following persons: (i) British Aerospace Holdings, Inc. ("BAe"), a
Delaware corporation, (ii) British Aerospace Communications, Inc. ("BAC"), a
Delaware corporation, (iii) British Aerospace Satellite Investments, Inc.
("BASI"), a Delaware corporation formerly known as British Aerospace Space
Systems, Inc., and (iv) British Aerospace Plc ("PLC"), a company existing under
the laws of England and Wales.  BAC and BASI are each wholly owned subsidiaries
of BAe which, in turn, is an indirect wholly owned subsidiary of PLC.

                  The principal business office and principal business activity
of each of the Reporting Persons is as follows:

                  (a)      BAe

                           15000 Conference Center Drive
                           Chantilly, Virginia 20151

                           Principal Business Activity:

                           Top-tier U.S. holding company for PLC's U.S. 
                           interests.

                  (b)      BAC:

                           15000 Conference Center Drive
                           Chantilly, Virginia 20151

                           Principal Business Activity:

                           Ownership of securities of the Issuer.

                  (c)      BASI:


                           15000 Conference Center Drive
                           Chantilly, Virginia 20151

                           Principal Business Activity:

                           Ownership of securities of the Issuer.

                                      6

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                  (d)      PLC:

                           Warwick House, P.O. Box 87
                           Farnborough Aerospace Centre
                           Farnborough, Hampshire, GU14   6YU, United Kingdom

                           Principal Business Activity:

                           Parent holding company that through its subsidiaries
                           is principally engaged in the defense business
                           (manufacture and sale of military aircraft, guided
                           weapons, ordnance and electronic systems), the
                           commercial aerospace business (design and production
                           of wings for Airbus Industrie jets, manufacture of
                           regional airliners and turboprop aircraft and
                           secondary marketing and servicing of commercial
                           aircraft) and the property development business.

                  Information regarding the executive officers and directors of
each of the Reporting Persons is as follows:

                  (a)      Identity - Refer to Annex A

                  (b)      Residence or Business Address - Refer to Annex A

                  (c)      Present principal occupation or employment - Refer 
                           to Annex A

                  (d)-(e)  None of the Reporting Persons and none of the
                           directors or executive officers who are identified on
                           Annex A have been convicted in a criminal proceeding
                           (excluding traffic violations or similar
                           misdemeanors) or been a party to a civil proceeding
                           of a judicial or administrative body of jurisdiction
                           that resulted in a judgment, decree or final order
                           enjoining future violations of, or prohibiting or
                           mandating activities subject to U.S. federal or state
                           securities laws or finding any violations with
                           respect to such laws.

                  (f)      Citizenship - Refer to Annex A


Item 3.  Source and Amount of Funds or Other Consideration

                  (1)      Purchase of $50,000,000 principal amount of
                           Convertible Junior Subordinated Debentures, Due
                           February 1, 2012 (Interest Payable in Common Stock)
                           (the "Debenture") by BAe - The source of the
                           $50,000,000 for BAe's purchase of the Debenture was
                           BAe's working capital which was derived from an
                           advance of funds from PLC to BAe.

                  (2)      Exercise of Warrant for 86,505 shares of Oldco (as
                           hereinafter defined) Common Stock by BAC - The source
                           of the $999,998 used by BAC for the exercise of the
                           warrant to purchase 86,505 Oldco shares was BAC's own
                           working capital.

                  (3)      Acquisition of 85,715 shares of Oldco Common Stock
                           (as hereinafter defined) by BASI - BASI acquired the
                           85,715 shares of Oldco Common Stock in exchange for
                           all of BASI's interest (422,347 shares of Common
                           Stock) in Asia Pacific Space and Communications Ltd.
                           ("APSC").

                  (4)      Acquisition of 50,722 shares of the 6% Series C
                           Cumulative Redeemable Convertible Preferred Stock
                           ("Series C Stock") of the Issuer by BAC - BAC
                           acquired 50,722 shares of Series C Stock in exchange
                           for all of BAC's limited

                                      7


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                           partnership interest (25% of all limited partnership
                           interests) in International Private Satellite
                           Partners, L.P. ("Orion Atlantic") and in exchange
                           for refund rights of BAC related to certain advances
                           made by BAC to Orion Atlantic.  As described in Item
                           6. below, BAC is entitled to receive an additional
                           1,914 shares of Series C Stock from MCN Sat U.S.
                           Inc. ("MCN").

                  The Debentures and the Series C Stock are sometime hereinafter
together referred to as the "Convertible Instruments".

Item 4.  Purpose of Transaction

                  The acquisition by BAC and BASI of additional shares of common
stock, par value $.01 per share of the Oldco ("Oldco Common Stock") and by BAC
and BAe of securities of the Issuer convertible into Common Stock (collectively

the "Acquisition Transactions") were undertaken in conjunction with certain
reorganization and recapitalization transactions of the Issuer, Oldco, and Orion
Atlantic (the "Restructuring Transactions"). The principal elements of the
Restructuring Transactions were (i) the merger of a special purpose merger
subsidiary into Orion Network Systems, Inc. ("ONS") and the exchange, pursuant
to the merger of each of the preferred and common shares of ONS for preferred
and common shares of Orion Newco Services, Inc., (ii) the exchange by BAC, COM
DEV Satellite Communications Limited, Kingston Communications International
Limited, Lockheed Martin Commercial Launch Services, Inc., MCN, and Trans
Atlantic Satellite, Inc. (collectively the "Exchanging Partners") of their
limited partnership interests in Orion Atlantic and certain refund rights for
shares of Series C Stock of the Issuer; (iii) an aggregate investment of
$60,000,000 by BAe and Matra Marconi Space UK Limited ("Matra") in the Issuer in
the form of convertible junior subordinated debentures, (iv) the exchange by
BASI of its interest in APSC for shares of Oldco and (v) the public sale by the
Issuer of units of senior notes and common stock warrants in the approximate
amount of $710,000,000 resulting in net proceeds to the Issuer of approximately
$575,000,000 after provision for certain pre-funded interest payments.

                  Upon completion of the Restructuring Transactions, ONS became
a wholly owned subsidiary of the Issuer and changed its name from Orion Network
Systems, Inc. to Orion Oldco Services, Inc. ("Oldco") and the Issuer changed
its name from Orion Newco Services, Inc. to Orion Network Systems, Inc.

                  The Restructuring Transactions also resulted in the
refinancing of $210,000,000 of existing indebtedness of Orion Atlantic under a
credit agreement (together with any related documents and agreements, the "Orion
1 Credit Facility") dated December 6, 1991 among Orion Atlantic, certain banks
and other lenders and the Chase Manhattan Bank (National Association), as agent
and the release of commitments of the Exchanging Partners (including BAC and
another affiliate of the Reporting Persons) to support the Orion 1 Credit
Facility pursuant to certain Communication Satellite Capacity Agreements and
Contingent Communication Satellite Capacity Agreements. In addition, in
connection with the refinancing, PLC was released from its guarantee of the
Orion 1 Credit Facility and certain other credit support obligations related to
Oldco.

                  The Reporting Persons undertook the Acquisition Transactions
both for investment purposes and for the purpose of ensuring that the
refinancing of the Orion 1 Credit Facility (and the related termination of the
obligations of the Reporting Persons and their affiliates to support the Orion 1
Credit Facility) was successfully consummated.

                  BASI sold 125,000 Oldco Common Shares in two tranches (on
December 19 and December 31, 1996). BAC exercised its warrant and acquired
86,505 additional Oldco Common Shares on December 31, 1996. The sale of the 
shares and the exercise of the warrant were undertaken in order to take 
advantage of an attractive warrant

                                      8


<PAGE>




exercise price, while minimizing any changes in the Reporting Persons' ownership
interest in the Common Stock prior to the completion of the Restructuring
Transactions.

                  The shares of Common Stock and Convertible Instruments owned
by the Reporting Persons are being held for investment purposes. Subject to
contractual and legal restrictions or limitations, economic and market
conditions and such other considerations as they may deem relevant, the
Reporting Persons may, from time to time, acquire additional shares of Common
Stock or additional Convertible Instruments in the open market, in private
transactions or otherwise. The Reporting Persons may also dispose of some or all
of the shares of Common Stock or Convertible Instruments owned by them, in the
open market, in private transactions or otherwise. The Issuer is obligated to
pay dividends on the Series C Preferred Stock and to pay interest on the
Debenture in the form of additional shares of Common Stock. For as long as any
of the Reporting Persons own any shares of Series C Stock or any portion of the
Debenture, they will receive additional shares of Common Stock from the Issuer
in accordance with the terms of the Series C Stock and the Debenture.

                  Except as discussed in the immediately preceding paragraph,
none of the Reporting Persons presently has any plans or proposals which related
to or would result in any of the actions described in clauses (a) through (j) of
the instructions to Item 4 to Schedule 13D or in any action similar to any of
those enumerated in said clauses (a) through (j).

Item 5.  Interest in Securities of the Issuer

         (a) BASI owns 472,391 shares of Common Stock. BAC owns 86,505 shares of
Common Stock and owns (or is presently entitled to own) 52,636 shares of Series
C Stock that at the date of issuance (January 31, 1997) were convertible into
3,007,771 shares of Common Stock. BAe owns the Debenture, which at the date of
issuance (January 31, 1997) was convertible into 3,571,429 shares of Common
Stock. Collectively, as of January 31, 1997, the Reporting Persons owned or had
an immediate right to acquire upon conversion 7,138,096 shares of Common Stock
or approximately 40.7% of the total number of shares of Common Stock issued and
outstanding as reported in the Issuer's proxy statement dated January 15, 1997,
as calculated in accordance with Rule 13d-3(d)(1). In addition, W. Anthony Rice,
a director of both BASI and the Issuer has the right to acquire 10,000 shares of
Common Stock as a result of options received by him in January 1996 pursuant to
the Non-Employee Director Stock Option Plan of Oldco. Mr. Rice is entitled to
exercise the options for a price equal to 100% of the fair market value of Oldco
Common Stock as of the date his options were granted.

         As a result of its ownership of all of the issued and outstanding
shares of each of BASI and BAC, BAe may be deemed to be a beneficial owner of
the shares of Common Stock and Convertible Instruments owned directly by BASI
and BAC. As a result of its indirect ownership of each of the other Reporting
Persons, PLC may be deemed to be the indirect beneficial owner of all of the
shares of Common Stock and Convertible Instruments owned directly by each of the
other Reporting Persons. Mr. Rice has sole ownership of the option to acquire
shares held in his name and he disclaims beneficial ownership of any Common
Stock or Convertible Instruments by any of the Reporting Persons.


         (b) By reason of its direct ownership of 100% of the voting securities
of BASI and BAC, BAe may be deemed to share voting and dispositive power over
all the shares of Common Stock and Convertible Instruments directly owned by
BASI and BAC. PLC may be deemed to share voting and dispositive power over all
of the shares of Common Stock and Convertible Instruments directly owned by each
of the other Reporting Persons as a result of its indirect ownership of 100% of
the voting securities of each of the other Reporting Persons.

         (c) Set forth on Annex B hereto is a description of all transactions in
the Common Stock of the Issuer effected by the Reporting Persons during the past
sixty days.

                                      9


<PAGE>



         (d)      Not applicable.

         (e)      Not applicable.

Item 6.  Contracts, Arrangements, Understandings or Relationships With 
         Respect to Securities of the Issuer

         In connection with the Acquisition Transactions, the Reporting Persons
have entered into the contracts described below relating to the securities of
the Issuer. Each of the following summaries of agreements are qualified by
reference to the full text of such agreement, each of which is filed herewith as
an exhibit to this statement on Schedule 13D and are either attached hereto or
are incorporated herein by reference to filings made with the Securities and
Exchange Commission by either the Issuer or Oldco:

         Debenture Purchase Agreement, dated as of January 13, 1997 and as
         amended as of January 31, 1997 among Oldco, the Issuer, BAe and Matra
         ("Debenture Purchase Agreement") - Pursuant to the Debenture Purchase
         Agreement BAe purchased a Debenture in the principal amount of
         $50,000,000 and Matra acquired Debentures in the aggregate principal
         amount of $10,000,000 at the purchase price of 100% of such principal
         amount. The Debenture Purchase Agreement provides for the payment by
         the Issuer of interest semi-annually, commencing on August 1, 1997, in
         the form of additional shares of the Common Stock. The number of shares
         to be distributed as interest is calculated by multiplying the
         principal amount of outstanding Debentures by 8.75%, dividing the
         result by an applicable divisor that ranges from $10.21 to 14,
         depending upon market price of the Common Stock, and multiplying the
         result by a fraction equal to the number of days elapsed since the
         previous interest payment over 360. Unpaid interest in the form of
         additional shares of Common Stock is also payable upon the stated
         maturity of the Debenture (February 1, 2012) and upon any earlier
         conversion, redemption or repurchase of all or some portion of the
         Debenture. The initial conversion rate is 71.4286 Common Shares per

         $1,000 of principal amount of Debenture (a conversion price of $14 per
         share) subject to adjustment for certain sales or other distributions
         of securities by the Issuer and certain other events, as described in
         the Debenture Purchase Agreement. The Debenture Purchase Agreement also
         contains certain provisions regarding, inter alia (i) the redemption or
         repurchase of the Debenture or underlying shares of Common Stock, (ii)
         Issuer events of default and (iii) certain business and financial
         covenants.

         Registration Rights Agreement dated as of January 31, 1997 among the
         Issuer, BAe and Matra ("Debenture Registration Rights Agreement") -
         Pursuant to the Debenture Registration Rights Agreement, the Issuer has
         granted BAe and Matra certain demand, shelf and "piggy-back"
         registration rights with respect to shares of Common Stock received
         upon any conversion of Debentures and any shares received as interest
         on the Debentures. The Debenture Registration Rights Agreement also
         provides for registration of (i) 86,505 shares of Common Stock owned by
         BAC (arising from the Oldco Common Stock received by BAC on exercise of
         a warrant on December 31, 1996) and (ii) 85,715 shares of Common Stock
         owned by BASI (arising from the Oldco Common Stock received by BASI
         upon exchange of the APSC shares owned by BASI).

         Exchange Agreement dated as of January 8, 1997 between Oldco and BASI
         ("APSC Exchange Agreement") - Pursuant to the APSC Exchange Agreement,
         BASI acquired 85,715 shares of Oldco Common Stock in exchange for
         422,347 shares of APSC Common Stock owned by BASI. As a result of this
         exchange, Oldco became the owner of 100% of the voting securities of
         APSC.

         Section 351 Exchange Agreement and Plan of Conversion, dated as of June
         __, 1996 ("Exchange Agreement") and First Amendment to Section 351
         Exchange Agreement and Plan of Conversion dated as of December , 1996
         among Orion Atlantic, Oldco, OrionSat

                                      10


<PAGE>



         and the Exchanging Partners (the "First Amendment") - Pursuant to the
         Exchange Agreement and the First Amendment, the Exchanging Partners
         (including BAC) received shares of Series C Stock of the Issuer in
         exchange for all of their limited partnership interests in Orion
         Atlantic and all of their rights to refunds of certain advances made by
         the Exchanging Partners to Orion Atlantic. The Exchange Agreement also,
         among other things, required the termination of the obligations of the
         Exchanging Partners and their affiliates with respect to the Orion 1
         Credit Facility. Under the registration rights agreement attached as
         Exhibit D to the Exchange Agreement (the "Exchanging Partner
         Registration Rights Agreement") the Issuer is obligated to provide
         certain demand, shelf and "piggy back" registration rights to the
         holders of the Series C Stock with respect to shares of Common Stock

         they receive as dividends on the Series C or upon conversion of the
         Series C Stock. Under a resale restriction letter agreement (the
         "Resale Restriction Letter"), attached as Exhibit E to the Exchange
         Agreement, the Exchanging Partners have agreed not to transfer any of
         the shares of Common Stock received as dividends or upon conversion for
         a period of 180 days from the date of issuance of the Series C Stock
         (January 31, 1997) without the prior consent of the Issuer and to limit
         their aggregate sales of such shares for a period of 5 years to no more
         than 25% of the total available in any 90 days period, except pursuant
         to a underwritten, registered public offering or in certain other
         circumstances.

         Certificate of Designation, Rights and Preferences of Series C 6%
         Cumulative Redeemable Convertible Preferred Stock (the "Certificate of
         Designation") - The Certificate of Designation, which establishes the
         terms of the Series C Stock provides, among other things, for a 6%
         annual cumulative dividend to be paid only in shares of Common Stock
         (except for dividends of fractional shares which are to be paid in
         cash). The number of shares of Common Stock to be distributed in
         satisfaction of the dividend on the Series C Stock is determined by
         dividing the dividend entitlement (6% per annum on the outstanding
         Series C Stock) by the higher of (a) the average market price per share
         of Common Stock over a period of 20 consecutive business days
         immediately preceding the dividend reference date or (b) a price of
         $10.21 (subject to adjustments for stock splits, recapitalizations or
         other subdivisions of the Common Stock). Dividends are paid annually,
         upon conversion of any shares of Series C Stock, the date on which a
         liquidation payment is made and upon final maturity (February 1, 2022).
         The holders of the Series C Stock are entitled to vote their Series C
         Stock on an "as converted basis" (i.e. one vote for each whole share of
         Common Stock that would be issuable upon conversion of such Series C
         Stock at the time the vote is taken.) The Series C Stock is subject to
         redemption and to mandatory conversion into Common Stock, as provided
         by the Certificate of Designation.

         Contingent Transponder Agreement dated January 26, 1995 among PLC,
         Matra Hachette S.A. and MCN ("Indemnity Agreement") and letter
         agreement dated December 23, 1996 among PLC, Lagardere Group SA and MCN
         ("MCN Share Transfer Agreement") Under the Indemnity Agreement PLC
         agreed to pay to MCN 75\175th of any contingent payment owed by MCN to
         Orion Atlantic and MCN agreed to reimburse PLC 75\175 of any contingent
         payment distributions made by Orion Atlantic to MCN. Pursuant to the
         Share Transfer Agreement MCN agreed to transfer to BAC certain shares
         of the Series C Stock in fulfillment of the reimbursement obligation
         under the Indemnity Agreement. As a result of the Share Transfer
         Agreement, within five days of its receipt of the Series C Stock MCN is
         obligated to effect the transfer of 1,914 shares of Series C Stock to
         BAC.

         Except as otherwise specifically disclosed in Item 5 (with respect to
Mr. Rice's stock option grant) and this Item 6, none of the Reporting Persons
and, to the knowledge of the Reporting Persons, none of the individuals
identified in Annex A have any contract, arrangement, understanding or
relationship among themselves or with any other person with respect to any

securities of the Issuer.

                                      11


<PAGE>



Item 7.  Materials to be filed as Exhibits

                  The following materials are filed as exhibits to this
statement of beneficial ownership on Schedule 13D and are either attached hereto
or are incorporated by reference to registrations statements or periodic reports
of the Issuer or Oldco filed with the Securities and Exchange Commission, as
permitted under Rule 12b-32 of the general rules and regulations under the
Securities Exchange Act of 1934:

                  1.       Joint Filing Agreement among BASI, BAC, BAe and PLC
                           dated February 10, 1997;

                  2.       The Debenture Purchase Agreement;

                  3.       The Debenture Registration Rights Agreement;

                  4.       The APSC Exchange Agreement;

                  5.       Exchange Agreement (including, Exchanging Partner
                           Registration Rights Agreement (Exhibit D thereto)
                           and Resale Restriction Letter (Exhibit E thereto));

                  6.       Form of Certificate of Designation of Series C 6%
                           Cumulative Redeemable Convertible Preferred Stock of
                           the Issuer;

                  7.       First Amendment to Exchange Agreement;

                  8.       Indemnity Agreement; and

                  9.       MCN Share Transfer Agreement.

                                      12

<PAGE>


         After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.


Date:    February 10, 1997

                             BRITISH AEROSPACE HOLDINGS, INC.


                             By:      /s/ Charles E. Gaba
                                      ______________________               
                             Name:    Charles E. Gaba
                             Title:   Vice President

                             BRITISH AEROSPACE Plc

                             By:      /s/ David Parkes
                                      ______________________
                             Name:    David Parkes
                             Title:   Assistant Secretary

                             BRITISH AEROSPACE COMMUNICATIONS, INC.

                             By:       /s/ Paul L. Harris
                                       ______________________
                             Name:     Paul L. Harris
                             Title:    President

                             BRITISH AEROSPACE SATELLITE INVESTMENTS, INC.

                             By:       /s/ Charles E. Gaba
                                       ______________________
                             Name:     Charles E. Gaba
                             Title:    Vice President

                                      13

<PAGE>



                                   ANNEX A
                                      
          DIRECTORS AND EXECUTIVE OFFICERS OF THE REPORTING PERSONS
                                      
BRITISH AEROSPACE PLC
NON-EXECUTIVE DIRECTORS

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<CAPTION>
==================================================================================================================
      Name and Title; Principal                            Address                            Citizenship
              Occupation
- ------------------------------------------------------------------------------------------------------------------
- ------------------------------------------------------------------------------------------------------------------
<S>                                      <C>                                           <C>
Mr. Robert Bauman                        P.O. Box 87                                             U.S.
Chairman                                 Farnborough Aerospace Centre
                                         Farnborough, Hants GU14 6YU
                                         England
- ------------------------------------------------------------------------------------------------------------------
Mr. Robert Leonard Kirk                  1101 Wilson Boulevard                                   U.S.
Director;                                Suite 1200
Chairman                                 Arlington, Virginia  22209
British Aerospace Holdings,
Inc.
- ------------------------------------------------------------------------------------------------------------------
Sir Robin Adair Biggam                   33 Foley Street                                         U.K.
Director;                                London, England W1P 7LB
Chairman
Independent Television
Commission
- ------------------------------------------------------------------------------------------------------------------
Lord Hesketh                             33 Cork Street                                          U.K.
(Thomas Alexander)                       5th Floor
Director                                 London, England W1X 1HB
- ------------------------------------------------------------------------------------------------------------------
Mr. Keith Clark Brown                    25 Cabor Square                                         U.K.
Director;                                Canary Wharf
Managing Director                        London, England B14 4QA
Morgan Stanley International
- ------------------------------------------------------------------------------------------------------------------
Sir Ronald Clause Hampel                 9 Millbank                                              U.K.
Director;                                London, England  SW1P 3JF
Executive Chairman
I.C.I. Plc
- ------------------------------------------------------------------------------------------------------------------
Lord Hollick                             Ludgate House                                           U.K.
(Clive Richard)                          245 Blackfriars Road
Director;                                London, England SE1 9UY
Chief Executive
United News & Media plc
==================================================================================================================

</TABLE>

                                      14

<PAGE>


BRITISH AEROSPACE PLC
EXECUTIVE DIRECTORS

<TABLE>
<CAPTION>
==================================================================================================================
      Name and Title; Principal                            Address                            Citizenship
              Occupation
- ------------------------------------------------------------------------------------------------------------------
- ------------------------------------------------------------------------------------------------------------------
<S>                                      <C>                                           <C>
Sir Richard Evans                        P.O. Box 87                                             U.K.
Executive Director                       Farnborough Aerospace Centre
and Chief Executive                      Farnborough, Hants GU14 6YU
                                         England
- ------------------------------------------------------------------------------------------------------------------
Mr. Michael Turner                       P.O. Box 87                                             U.K.
Executive Director and                   Farnborough Aerospace Centre
Group Managing Director                  Farnborough, Hants GU14 6YU
                                         England
- ------------------------------------------------------------------------------------------------------------------
Mr. Richard Lapthorne                    P.O. Box 87                                             U.K.
Executive Director and                   Farnborough Aerospace Centre
Finance Director                         Farnborough, Hants GU14 6YU
                                         England
- ------------------------------------------------------------------------------------------------------------------
Mr. John Weston                          P.O. Box 87                                             U.K.
Executive Director and                   Farnborough Aerospace Centre
Group Managing Director                  Farnborough, Hants GU14 6YU
                                         England
==================================================================================================================
</TABLE>

                                      15


<PAGE>


BRITISH AEROSPACE PLC
EXECUTIVE OFFICERS

<TABLE>
<CAPTION>
==================================================================================================================
      Name and Title; Principal                            Address                            Citizenship
              Occupation

- ------------------------------------------------------------------------------------------------------------------
- ------------------------------------------------------------------------------------------------------------------
<S>                                      <C>                                           <C>
Stuart Carroll, Esq.                     P.O. Box 87                                             U.K.
Secretary                                Farnborough Aerospace Centre
                                         Farnborough, Hants GU14 6YU
                                         England
- ------------------------------------------------------------------------------------------------------------------
Mr. David Brent                          P.O. Box 87                                             U.K.
Treasurer                                Farnborough Aerospace Centre
                                         Farnborough, Hants GU14 6YU
                                         England
==================================================================================================================
</TABLE>

                                      16


<PAGE>



BRITISH AEROSPACE HOLDINGS, INC.
DIRECTORS

<TABLE>
<CAPTION>
==================================================================================================================
      Name and Title; Principal                            Address                            Citizenship
              Occupation
- ------------------------------------------------------------------------------------------------------------------
- ------------------------------------------------------------------------------------------------------------------
<S>                                      <C>                                           <C>
Mr. Robert Leonard Kirk                  1101 Wilson Boulevard                                   U.S.
Chairman;                                Suite 1200
British Aerospace Holdings,              Arlington, Virginia  22209
Inc.
- ------------------------------------------------------------------------------------------------------------------
Sir Richard Evans                        P.O. Box 87                                             U.K.
Director;                                Farnborough Aerospace Centre
Executive Director                       Farnborough, Hants GU14 6YU
British Aerospace Plc                    England
- ------------------------------------------------------------------------------------------------------------------
Mr. Samuel L. Higginbottom               One Alhambra Plaza                                      U.S.
Director;                                Suite 1115
Chairman and CEO (retired)               Coral Gables, Florida  33134
Rolls Royce, Inc.
- ------------------------------------------------------------------------------------------------------------------
Mr. Michael Raoul-Duval                  17 Wilderness Gale                                      U.S.
Director;                                Sante Fe, New Mexico  87501
Investment Banker
==================================================================================================================
</TABLE>


BRITISH AEROSPACE HOLDINGS, INC.
OFFICERS

<TABLE>
<CAPTION>
==================================================================================================================
      Name and Title; Principal                            Address                            Citizenship
              Occupation
- ------------------------------------------------------------------------------------------------------------------
- ------------------------------------------------------------------------------------------------------------------
<S>                                      <C>                                           <C>
Paul L. Harris                           15000 Conference Center Drive                           U.S.
Senior Vice President &                  Conference Center Drive
General  Manager                         Chantilly, Virginia  20151
British Aerospace Holdings,
Inc.
- ------------------------------------------------------------------------------------------------------------------
Charles E. Gaba                          15000 Conference Center Drive                           U.S.
Vice President, General                  Conference Center Drive
Counsel & Secretary                      Chantilly, Virginia  20151
British Aerospace Holdings,
Inc.
- ------------------------------------------------------------------------------------------------------------------
Richard E. Wise                          1101 Wilson Boulevard                                   U.K.
Vice President - Government              Suite 1200
Programs                                 Arlington, Virginia  22209
British Aerospace Holdings,
Inc.
- ------------------------------------------------------------------------------------------------------------------
David P. Loose                           15000 Conference Center Drive                           U.S.
Treasurer                                Conference Center Drive
British Aerospace Holdings,              Chantilly, Virginia  20151
Inc.
==================================================================================================================
</TABLE>

                                      17


<PAGE>


<TABLE>
<CAPTION>
==================================================================================================================
      Name and Title; Principal                            Address                            Citizenship
              Occupation
- ------------------------------------------------------------------------------------------------------------------
- ------------------------------------------------------------------------------------------------------------------
<S>                                      <C>                                           <C>
Patricia L. Maskell                      15000 Conference Center Drive                           U.S.
Assistant Secretary                      Conference Center Drive
British Aerospace Holdings,              Chantilly, Virginia  20151
Inc.

==================================================================================================================
</TABLE>

                                      18

<PAGE>


BRITISH AEROSPACE COMMUNICATIONS, INC.
DIRECTORS

<TABLE>
<CAPTION>
==================================================================================================================
      Name and Title; Principal                            Address                            Citizenship
              Occupation
- ------------------------------------------------------------------------------------------------------------------
- ------------------------------------------------------------------------------------------------------------------
<S>                                      <C>                                           <C>
W. Anthony Rice                          15000 Conference Center Drive                           U.K.
Director;                                Conference Center Drive
Chief Executive Officer                  Chantilly, Virginia  20151
British Aerospace Asset
Management
- ------------------------------------------------------------------------------------------------------------------
Paul L. Harris                           15000 Conference Center Drive                           U.S.
Director;                                Conference Center Drive
Senior Vice President &                  Chantilly, Virginia  20151
General  Manager
British Aerospace Holdings,
Inc.
- ------------------------------------------------------------------------------------------------------------------
Charles E. Gaba, Esq.                    15000 Conference Center Drive                           U.S.
Director;                                Conference Center Drive
Vice President, General                  Chantilly, Virginia  20151
Counsel & Secretary
British Aerospace Holdings,
Inc.
==================================================================================================================
</TABLE>


BRITISH AEROSPACE COMMUNICATIONS, INC.
OFFICERS

<TABLE>
<CAPTION>
==================================================================================================================
      Name and Title; Principal                            Address                            Citizenship
              Occupation
- ------------------------------------------------------------------------------------------------------------------
- ------------------------------------------------------------------------------------------------------------------
<S>                                      <C>                                           <C>
Paul L. Harris                           15000 Conference Center Drive                           U.S.

President;                               Conference Center Drive
Senior Vice President,  &                Chantilly, Virginia  20151
General Manager
British Aerospace Holdings,
Inc.
- ------------------------------------------------------------------------------------------------------------------
J. Daniel Frix                           15000 Conference Center Drive                           U.S.
Vice President;                          Conference Center Drive
Controller                               Chantilly, Virginia  20151
British Aerospace Holdings, Inc.
- ------------------------------------------------------------------------------------------------------------------
David P. Loose                           15000 Conference Center Drive                           U.S.
Vice President;                          Conference Center Drive
Treasurer of British                     Chantilly, Virginia  20151
Aerospace Holdings, Inc.
- ------------------------------------------------------------------------------------------------------------------
</TABLE>
                                       
                                      19


<PAGE>

<TABLE>
<CAPTION>
==================================================================================================================
      Name and Title; Principal                            Address                            Citizenship
              Occupation
- ------------------------------------------------------------------------------------------------------------------
- ------------------------------------------------------------------------------------------------------------------
<S>                                      <C>                                           <C>
Martin Newton                            15000 Conference Center Drive                           U.K.
Treasurer;                               Conference Center Drive
Assistant Treasurer-U.S.                 Chantilly, Virginia  20151
British Aerospace Holdings, Inc.
- ------------------------------------------------------------------------------------------------------------------
Charles E. Gaba                          15000 Conference Center Drive                           U.S.
Assistant Secretary;                     Conference Center Drive
Vice President, General                  Chantilly, Virginia  20151
Counsel & Secretary
British Aerospace Holdings,
Inc.
- ------------------------------------------------------------------------------------------------------------------
Tedson Meyers                            1627 I Street, N.W.                                     U.S.
Secretary;                               Washington, D.C. 20006
Attorney - Coudert Brothers
==================================================================================================================
</TABLE>

                                      20


<PAGE>




BRITISH AEROSPACE SATELLITE INVESTMENTS, INC.
DIRECTORS

<TABLE>
<CAPTION>
==================================================================================================================
      Name and Title; Principal                            Address                            Citizenship
              Occupation
- ------------------------------------------------------------------------------------------------------------------
- ------------------------------------------------------------------------------------------------------------------
<S>                                      <C>                                             <C>
W. Anthony Rice                          15000 Conference Center Drive                           U.K.
Director;                                Conference Center Drive
Chief Executive Officer                  Chantilly, Virginia  20151
British Aerospace Asset
Management
- ------------------------------------------------------------------------------------------------------------------
Paul L. Harris                           15000 Conference Center Drive                           U.S.
Director;                                Conference Center Drive
Senior Vice President,  &                Chantilly, Virginia  20151
General Manager
British Aerospace Holdings,
Inc.
- ------------------------------------------------------------------------------------------------------------------
Charles E. Gaba, Esq.                    15000 Conference Center Drive                           U.S.
Director;                                Conference Center Drive
Vice President, General                  Chantilly, Virginia  20151
Counsel & Secretary
British Aerospace Holdings,
Inc.
==================================================================================================================
</TABLE>


BRITISH AEROSPACE SATELLITE INVESTMENTS, INC.
OFFICERS

<TABLE>
<CAPTION>
==================================================================================================================
      Name and Title; Principal                            Address                            Citizenship
              Occupation
- ------------------------------------------------------------------------------------------------------------------
- ------------------------------------------------------------------------------------------------------------------
<S>                                      <C>                                                <C>
Paul L. Harris                           15000 Conference Center Drive                           U.S.
President;                               Conference Center Drive
Senior Vice President,  &                Chantilly, Virginia  20151
General Manager
British Aerospace Holdings,
Inc.
- ------------------------------------------------------------------------------------------------------------------
J. Daniel Frix                           15000 Conference Center Drive                           U.S.
Vice President;                          Conference Center Drive

Controller                               Chantilly, Virginia  20151
British Aerospace Holdings, Inc.
- ------------------------------------------------------------------------------------------------------------------
Lee Bambridge                            P.O. Box 87                                             U.K.
Vice President;                          Farnborough Aerospace Centre
Assistant Treasurer of British           Farnborough, Hants GU14 6YU
Aerospace Plc                            England
- ------------------------------------------------------------------------------------------------------------------
</TABLE>

                                      21

<PAGE>


<TABLE>
<CAPTION>
==================================================================================================================
      Name and Title; Principal                            Address                            Citizenship
              Occupation
- ------------------------------------------------------------------------------------------------------------------
- ------------------------------------------------------------------------------------------------------------------
<S>                                      <C>                                                <C>
Charles E. Gaba                          15000 Conference Center Drive                           U.S.
Vice President; Assistant Secretary;     Conference Center Drive
Vice President, General                  Chantilly, Virginia  20151
Counsel & Secretary
British Aerospace Holdings,
Inc.
- ------------------------------------------------------------------------------------------------------------------
Martin Newton                            15000 Conference Center Drive                           U.K.
Treasurer;                               Conference Center Drive
Assistant Treasurer-U.S.                 Chantilly, Virginia  20151
British Aerospace Holdings, Inc.
- ------------------------------------------------------------------------------------------------------------------
Tedson Meyers                            1627 I Street, N.W.                                     U.S.
Secretary;                               Washington, D.C. 20006
Attorney - Coudert Brothers
==================================================================================================================
</TABLE>

                                      22

<PAGE>

                                       
                                    ANNEX B
                                       
        TRANSACTIONS BY THE REPORTING PERSONS IN THE SECURITIES OF THE
                       ISSUER DURING THE PAST SIXTY DAYS

I.       Transactions by BASI)1)

         A.       Sold 25,000 shares of Common Stock of Oldco on December 19,
1996 in a brokerage transaction effected through Bear Stearns & Co. in the
over-the-counter market at $12.85 per share.  BASI received  net proceeds of
$321,247.50 from the sale of these shares.

         B.       Sold 100,000 shares of Common Stock of Oldco on December 31,
1996 in a brokerage transaction effected through Bear Stearns & Co. in the
over-the-counter market at $12.75 per share.  BASI received  net proceeds of
$1,274,997.50 from the sale of these shares.

         C.       Acquired 85,715 shares of the Common Stock of Oldco directly
from Oldco in exchange for 422,347 shares of common stock of APSC on  January
8, 1997.

II.      Transactions by BAC

         A.       Acquired 86,505 shares of the Common Stock of Oldco directly
from Oldco upon exercise of a warrant on December 31, 1996. The exercise price
paid to Oldco by BAC was $11.56 per share or $999,998.

         B.       Acquired 50,722 shares of Series C Preferred Stock directly
from the Issuer on January 31, 1997 in exchange for all of its limited
partnership interest (25% of total limited partnership interests) in Orion
Atlantic and in exchange for the right to receive certain refund payments.

         C.       Entitled to acquire 1,914 shares of Series C Preferred Stock
from MCN within five days of completion of the Restructuring Transactions under
the terms of the MCN Share Transfer Agreement.

III.     Transaction by BAe

         Acquired $50,000,000 principal amount of Debenture directly from the
Issuer on January 31, 1997 upon cash payment of $50,000,000.

- --------
(1)  As a result of the Merger, each of BASI's shares of Common Stock in Oldco
     were exchanged for one share of Common Stock of the Issuer.

                                      23

<PAGE>

                                EXHIBIT INDEX

EXHIBIT                               TITLE

NO.

1                    Joint filing agreement among BAe, PLC, BAC and BASI dated
                     February 10, 1997.

2                    Debenture Purchase Agreement among Oldco, the Issuer, BAe
                     and Matra dated as of January 13, 1997 and as amended as of
                     January 31, 1997

3                    Registration Rights Agreement dated as of January 31, 1997
                     among the Issuer, BAe and Matra

4                    Exchange Agreement dated as of January 8, 1997 between
                     Oldco and BASI

5                    Form of Certificate of Designation of Series C 6%
                     Cumulative Redeemable Convertible Preferred Stock of the
                     Issuer (Incorporated herein by reference to Exhibit 4.3 of
                     the Issuer's Registration Statement on Form S-4 No.
                     333-19795, dated January 15, 1997)

6                    Exchange Agreement dated June, 1996 among Oldco, Orion
                     Atlantic and each of the Exchanging Partners, including
                     Exchanging Partner Registration Rights Agreement (Exhibit D
                     thereto) and Resale Restriction Letter (Exhibit E thereto)
                     (Incorporated herein by reference to Exhibit 10 of Oldco's
                     Current Report on Form 8-K dated December 20, 1996)

7                    First Amendment to Exchange Agreement dated December      
                                  , 1996 among Oldco, Orion Atlantic, Orion
                     Satellite Corporation and each of the Exchanging Partners
                     (Incorporated herein by reference to Exhibit 10.45 of the
                     Issuer's Registration Statement on Form S-4 No. 333- 19795,
                     dated January 15, 1997)

8                    Indemnity Agreement dated January 26, 1995 among PLC, Matra
                     Hachette and MCN

9                    MCN Share Transfer Agreement dated December 23, 1996 among
                     PLC, Lagardere Group SA and MCN

                                                 
                                      24



<PAGE>

                                                                    EXHIBIT 1

                            JOINT FILING AGREEMENT

         The undersigned hereby agree that this statement on Schedule 13D dated
February 7, 1997 with respect to the Common Stock of Orion Network Systems, Inc.
is, and any amendments hereto signed by each of the undersigned shall be, filed
on behalf of each of us pursuant to and in accordance with the provisions of
Rule 13(d)-1(f) under the Securities Exchange Act of 1934.

Date:    February 10, 1997

                                       BRITISH AEROSPACE HOLDINGS, INC.

                                       By:  /s/ Charles E. Gaba
                                            -----------------------------
                                            Name: Charles E. Gaba
                                            Title: Vice President

                                       BRITISH AEROSPACE PLC

                                       By:  /s/ David Parkes
                                            -----------------------------
                                            Name: David Parkes
                                            Title: Assistant Secretary

                                       BRITISH AEROSPACE COMMUNICATIONS, INC.

                                       By:  /s/ Paul L. Harris
                                            -----------------------------
                                            Name: Paul L. Harris
                                            Title: President

                                       BRITISH AEROSPACE SATELLITE
                                       INVESTMENTS, INC.

                                       By:  /s/ Charles E. Gaba
                                            -----------------------------
                                            Name: Charles E. Gaba
                                            Title: Vice President




<PAGE>
                                                                      EXHIBIT 2

- -------------------------------------------------------------------------------
- -------------------------------------------------------------------------------


                           ORION NETWORK SYSTEMS, INC.

                                   $60,000,000

                   Convertible Junior Subordinated Debentures
             Due February 1, 2012 (Interest Payable in Common Stock)





                          -----------------------------
                          DEBENTURE PURCHASE AGREEMENT
                          -----------------------------



                          Dated as of January 13, 1997


                         Amended as of January 31, 1997





- -------------------------------------------------------------------------------
- -------------------------------------------------------------------------------

<PAGE>



                                Table of Contents

                                                                           Page


1.    Issuance of Debentures and the Subsidiary Guarantee.................  1
      1.1.       The Debentures...........................................  1
      1.2.       Sale of Debentures.......................................  1
      1.3.       The Subsidiary Guarantee.................................  2
      
2.    Closing.............................................................  2
      
3.    Use of Proceeds.....................................................  2


4.    Conditions to Closing...............................................  2
      4.1.       Representations and Warranties...........................  3
      4.2.       Exchange Agreement.......................................  3
      4.3.       Merger Transaction.......................................  3
      4.4.       Financing Transaction....................................  3
      4.5.       Termination of Your Prior Obligations....................  3
      4.6.       Subsidiary Guarantee.....................................  4
      4.7.       Registration Rights......................................  4
      4.8.       Opinions of Counsel......................................  4
      4.9.       Matra Incentive Payments.................................  5
      4.10.      Senior Notes.............................................  5
      4.11.      Terms of the Merger; Capitalization......................  5
      4.12.      HSR Clearance............................................  5
      4.13.      Investment by Each Purchaser.............................  6
      4.14.      Termination..............................................  6

5.    Representations, Warranties and Agreements of the Company and ONS...  7
      5.1.       Incorporation, Standing, etc.............................  7
      5.2.       Capital Stock............................................  7
      5.3.       Subsidiaries.............................................  8
      5.4.       Qualification............................................  8
      5.5.       Business; Financial Statements...........................  8
      5.6.       Solvency.................................................  9
      5.7.       Authorization of Agreement...............................  9
      5.8.       Authorization of Common Stock............................  9
      5.9.       Absence of Defaults and Conflicts........................  9
      5.10.      Absence of Labor Dispute................................. 10
      5.11.      Absence of Proceedings................................... 10
      5.12.      Possession of Licenses and Permits....................... 11
      5.13.      Environmental Laws....................................... 11
 
                                       (i)

<PAGE>



                                                                          Page

      5.14.      No Violations of Laws.................................... 12
      5.15.      Internal Accounting Controls............................. 12
      5.16.      Tax Returns and Payments................................. 12
      5.17.      Indebtedness............................................. 13
      5.18.      Title to Properties; Liens............................... 13
      5.19.      Patents, Trademarks, Authorizations, etc................. 13
      5.20.      Governmental Consents; Exercise of Voting Rights, etc.... 13
      5.21.      Offer of Debentures...................................... 14
      5.22.      Federal Reserve Regulations.............................. 14
      5.23.      Investment Company Act................................... 14
      5.24.      Public Utility Holding Company Act....................... 14
      5.25.      Compliance with ERISA.................................... 15
      5.26.      Disclosure............................................... 15
      5.27.      HSR Act Filings.......................................... 16
      5.28.      Certificate of Incorporation............................. 16

6.    Representations, Warranties and Agreements of Purchasers............ 17
      6.1.       Investment Representations............................... 17
      6.2.       ERISA.................................................... 17
      6.3.       HSR Act Filings.......................................... 17

7.    Accounting; Financial Statements; Other Information................. 18
      7.1.       Accounting; Financial Statements and Other Information... 18
      7.2.       Company Certificate...................................... 20
      7.3.       Accountant's Certificate................................. 20

8.    Inspection.......................................................... 20

9.    Confidential Treatment.............................................. 21

10.   ERISA............................................................... 21

11.   Redemption of Debentures; Repurchase Rights; Mandatory Sales........ 22
      11.1.      Right of Redemption...................................... 22
      11.2.      Company Right of Redemption.............................. 22
      11.3.      Redemption and Repurchase Rights upon Change of Control 
                 Event.................................................... 23
      11.4.      Mandatory Sale........................................... 24
      11.5.      Restriction on Conversion Rights; Withdrawal of Notice... 25

12.   Business Covenants.................................................. 26
      12.1.      Payment of Debentures and Maintenance of Office.......... 26
      12.2.      Payment of Taxes and Claims.............................. 27

                                      (ii)

<PAGE>


                                                                          Page


      12.3.      Maintenance of Properties and Corporate Existence........ 27
      12.4.      Compliance with Law...................................... 28
      12.5.      [Reserved.].............................................. 28
      12.6.      When Company May Merge, Etc.............................. 28
      12.7.      Listing.................................................. 29
      12.8.      Issuances of Guarantees by New Restricted Subsidiaries... 29
      12.9.      Subsidiaries............................................. 29
      12.10.     Notice................................................... 29
      12.11.     Waiver of Stay, Extension or Usury Laws.................. 29

13.   Financial Covenants................................................. 30
      13.1.      Merger and Sale of Assets................................ 30
      13.2.      Limitation on Transactions with Affiliates and
                 Shareholders............................................. 31
      13.3.      Tax Consolidation........................................ 32
      13.4.      Compliance with ERISA.................................... 32
      13.5.      Limitation on Indebtedness............................... 33
      13.6.      Limitation on Restricted Payments........................ 35
      13.7.      Limitation on the Issuance and Sale of Capital Stock of
                 Restricted Subsidiaries.................................. 37
      13.8.      Issuances of Guarantees by New Restricted Subsidiaries... 38
      13.9.      Limitation on Liens...................................... 38
      13.10.     Limitation on Sale-Leaseback Transactions................ 39
      13.11.     Limitation on Asset Sales................................ 39
      13.12.     Insurance................................................ 39

14.   Subordination of Debentures......................................... 41
      14.1.      Debentures Subordinated to Senior Indebtedness........... 41
      14.2.      Liquidation; Dissolution; Bankruptcy..................... 41
      14.3.      Default on Senior Indebtedness........................... 42
      14.4.      Payment Permitted If No Default.......................... 44
      14.5.      Subrogation to Rights of Holders of Senior Indebtedness.. 44
      14.6.      Provisions Solely to Define Relative Rights.............. 44
      14.7.      Enforcement of Subordination By Holders of Senior Notes;
                 No Waiver of Subordination Provisions.................... 45
      14.8.      Reliance on Judicial Order or Certificate of
                 Liquidating Agent........................................ 46
      14.9.      Certain Conversions Deemed Payment....................... 46
      14.10.     Not to Prevent Events of Default......................... 46

15.   Conversion Rights................................................... 46
      15.1.      Conversion Privilege and Conversion Rate................. 46
      15.2.      Exercise of Conversion Privilege; Time Conversion
                 Deemed Effected; Delivery of Stock Certificates;
                 Partial Conversions; Accrued Interest.................... 47

                                      (iii)

<PAGE>


                                                                          Page

      15.3.      Fractions of Shares...................................... 47

      15.4.      Adjustments to Conversion Rate........................... 48
      15.5.      Effect on Conversion Price of Certain Events............. 52
      15.6.      De Minimis Adjustments................................... 55
      15.7.      Notice of Adjustments of Conversion Rate................. 55
      15.8.      Notice of Certain Corporate Action....................... 55
      15.9.      Company to Reserve Common Stock.......................... 56
      15.10.     Taxes on Conversions..................................... 56
      15.11.     Agreements as to Common Stock; Listing................... 56
      15.12.     Cancellation of Converted Debentures..................... 57
      15.13.     Provision in Case of Consolidation, Merger or Conveyance
                 of Assets................................................ 57
      15.14.     Other Dilutive Events.................................... 58
      15.15.     Continuing Obligation of the Company..................... 59

16.   Registration, Transfer and Substitution of Debentures............... 59
      16.1.      Debenture Register; Ownership of Registered Debentures... 59
      16.2.      Transfer and Exchange of Debentures...................... 59
      16.3.      Replacement of Debentures................................ 59

17.   Payment............................................................. 60
      17.1.      Form of Payment.......................................... 60
      17.2.      Place of Payment......................................... 60
      17.3.      Home Office Payment...................................... 60

18.   Events of Default; Acceleration..................................... 61
      18.1.      Nature of Events and Acceleration of Debentures.......... 61
      18.2.      Default Remedies......................................... 63
      18.3.      Notice of Default........................................ 64
      18.4.      Annulment of Acceleration of Debentures.................. 64
      18.5.      Accelerations and other Remedies Limited Prior to
                 Senior Notes Reduction Date.............................. 64

19.   Interpretation of Agreement and Debentures.......................... 65

20.   Expenses............................................................ 88

21.   Survival............................................................ 89

22.   Amendments and Waivers.............................................. 89

23.   Notices............................................................. 89


                                      (iv)

<PAGE>


                                                                          Page

24.   Substitution of Purchaser........................................... 90

25.   Execution in Counterparts........................................... 90


27.   GOVERNING LAW....................................................... 90

28.   Consent to Jurisdiction; Appointment of Agent to Accept Service 
      of Process.......................................................... 90

29.   WAIVER OF JURY TRIAL................................................ 91


                                       (v)

<PAGE>



Schedule I          -      Schedule of Purchaser(s)

Schedule II         -      Exceptions to Section 5.11

Exhibit A           -      Form of Debenture

Exhibit B           -      Form of Subsidiary Guarantee

Exhibit C           -      Registration Rights Agreement

Exhibit D           -      Information Relating to Subsidiaries




                                      (vi)

<PAGE>


                           ORION NETWORK SYSTEMS, INC.



                                                          as of January 13, 1997
                                                  Amended as of January 31, 1997


British Aerospace Holdings, Inc.
15000 Conference Center Drive
Chantilly, Virginia  20151

Matra Marconi Space UK Limited
The Grove
Warren Land
Stanmore, Middlesex, HA7 4LY
England


Dear Sirs:

         ORION NETWORK SYSTEMS, INC., formerly known as Orion Newco Services,
Inc., a Delaware corporation (herein, together with its successors and assigns,
called the "Company"), and ORION OLDCO SERVICES, INC., formerly known as Orion
Network Systems, Inc., a Delaware corporation ("ONS"), agree with you as
follows:

         1.       Issuance of Debentures and the Subsidiary Guarantee.

                  1.1. The Debentures. The Company has duly authorized the issue
and sale of $60,000,000 in aggregate principal amount of its Convertible Junior
Subordinated Debentures Due February 1, 2012 (Interest Payable in Common Stock)
(such Debentures, together with all Debentures issued in substitution or
exchange therefor pursuant to this Agreement, are herein called the
"Debentures"). Each Debenture will bear interest from the date thereof on the
unpaid principal amount thereof at the rate specified therein, payable in Common
Stock semi-annually on the first day of February and the first day of August of
each year commencing with August 1, 1997, will mature on February 1, 2012, and
will be in substantially the form of Exhibit A attached hereto, with such
changes thereto, if any, as may be approved by you. Capitalized terms used and
not otherwise defined herein shall have the respective meanings assigned thereto
in Section 19.

                  1.2.      Sale of Debentures.

                  (a) The Company will issue and sell to BAe and, subject to the
terms and conditions hereof, BAe will purchase from the Company at the Closing
provided for in Section


<PAGE>




2, Debentures in the aggregate principal amount of $50,000,000 at the purchase
price of one hundred percent (100%) of such principal amount.

                  (b) The Company will issue and sell to Matra and, subject to
the terms and conditions hereof, Matra will purchase from the Company at the
Closing provided for in Section 2, Debentures in the aggregate principal amount
of $10,000,000 at the purchase price of one hundred percent (100%) of such
principal amount.

                  1.3. The Subsidiary Guarantee. The Guarantors, no later than
the Closing Date (as hereinafter defined), shall have taken all necessary action
to authorize the issuance of their unconditional guarantee of payment of the
Debentures as set forth in the Subsidiary Guarantee and to make their guarantee
of the Debentures the enforceable obligation it purports to be in accordance
with the terms of the Subsidiary Guarantee. The Subsidiary Guarantee is not
effective or enforceable against the Guarantors until the Senior Notes Reduction
Date. The Subsidiary Guarantee will become effective and enforceable against
each of the Guarantors on the Senior Notes Reduction Date without any further
action by any party.

         2. Closing. The closing of the sale of the Debentures to be purchased
by each Purchaser (the "Closing") shall take place at the offices of Coudert
Brothers, 1114 Avenue of the Americas, New York, New York 10036 at 10:00 a.m.,
New York City time, (or at such other time and place as the parties hereto may
agree) on the date on which the Financing Transaction is closed provided that
each of the conditions in Section 4 have been satisfied prior to such date or
are to be satisfied concurrently with the Closing (the "Closing Date"). At the
Closing the Company will deliver to each Purchaser the Debentures to be
purchased by such Purchaser, in the form of a single Debenture (or such greater
number of Debentures in denominations of at least $100,000 as such Purchaser may
request), dated the Closing Date and registered in such Purchaser's name (or the
name of such Purchaser's nominee), against delivery by such Purchaser to the
Company of the purchase price therefor by the same method of payment utilized in
the closing of the Financing Transaction. If at the Closing the Company shall
fail to tender such Debentures to a Purchaser as provided in this Section 2, or
any of the conditions specified in Section 4 shall not have been fulfilled to
such Purchaser's satisfaction, such Purchaser shall, at its election, be
relieved of all further obligations under this Agreement, without thereby
waiving any other rights such Purchaser may have by reason of such failure or
such non-fulfillment.

         3. Use of Proceeds. The proceeds of the sale of the Debentures will be
used to pay amount under the contracts for the construction of Orion 2 and Orion
3 and to provide working capital to the Company.

         4. Conditions to Closing. Each Purchaser's obligation to purchase and
pay for the Debentures to be purchased by such Purchaser is subject to the
fulfillment to such Purchaser's satisfaction, prior to or at the Closing, of
each of the following conditions:



                                       -2-

<PAGE>



                  4.1. Representations and Warranties. The representations and
warranties of the Company, ONS and their respective Subsidiaries contained in
this Agreement shall be correct as of the date hereof and at the time of the
Closing. Alternatively, the Company (and if applicable ONS) shall have made, in
writing, for the benefit of you and any other holder of Debentures, the same
representations, warranties and agreements as made to Morgan Stanley & Co.
Incorporated ("Morgan") in the underwriting agreement with respect to the sale
of the Senior Notes (the "Underwriting Agreement"), except that such
representations, warranties and agreements shall be made in connection with (and
with reference to) the offer, sale, delivery and performance of the Debentures
and this Agreement (including, without limitation, the issuance and delivery of
Conversion Shares and Interest Shares as required under the Debentures), rather
than with respect to the offer, sale, delivery and performance of the Senior
Notes, as the context requires, and such representations and warranties shall
have been correct as of the date first made and at the time of Closing. If the
Company or ONS shall make for the benefit of you and other holders of Debentures
such representations, warranties and agreements in the Underwriting Agreement,
the representations, warranties and agreements set forth in Sections 5.1 through
5.28 hereof shall not be updated through the Closing Date. In either case, each
Purchaser shall have received a certificate, dated the Closing Date and signed
by the Secretary of the Company, certifying as to the correctness of the
applicable representations and warranties.

                  4.2. Exchange Agreement. The transactions provided for in the
Exchange Agreement shall be completed prior to or concurrently with the Closing.

                  4.3. Merger Transaction. The Merger Transaction shall be
completed prior to or concurrently with the Closing.

                  4.4. Financing Transaction. The Financing Transaction shall be
completed prior to or concurrently with the Closing.

                  4.5.      Termination of Your Prior Obligations.

                  (a) As a condition to BAe's obligation to purchase and pay for
the Debentures to be purchased by BAe, the obligations of (i) BAC and BAC, Ltd.
under certain Communications Satellite Capacity Agreements each dated as of
December 20, 1991 by and between Orion Atlantic and BAC, and Orion Atlantic and
BAC Ltd. and certain Contingent Communications Satellite Capacity Agreements,
each dated as of December 20, 1991, by and between, Orion Atlantic and BAC, (ii)
British Aerospace Plc ("PLC") under the Guarantee Agreement dated as of February
19, 1992 between and among PLC, Orion Atlantic and The Chase Manhattan Bank
(National Association), as agent, (iii) BAC under a Communications Satellite
Capacity Agreement dated as of December 20, 1991 by and between Orion Atlantic
and Trans-Atlantic Satellite, Inc. and (iv) one or more guarantees of the
obligations of ONS and\or Orion Satellite Corporation under various
reimbursement agreements between ONS and certain banks in connection with
letters of credit from such banks in favor of STET-Societa Finanziaria

Telephonica per Azori (including, without limitation, all payment obligations,
guarantees or other credit support obligations under or related to each such
agreement) shall have been

                                       -3-

<PAGE>



terminated and be of no further force or effect and a termination of guarantee
agreement and termination of capacity agreements, substantially in the form of
the exhibits attached to the Exchange Agreement, in respect of the termination
of the obligations of PLC, BAC and BAC, Ltd. shall be executed and delivered
prior to or concurrently with the Closing.

                  (b) As a condition to Matra's obligation to purchase and pay
for the Debentures to be purchased by Matra, the obligations of (i) MCN Sat
Service S.A. under the Communications Satellite Capacity Agreement dated as of
December 20, 1991 by and between Orion Atlantic and MCN Sat Service S.A., (ii)
MCN Sat US, Inc. under the Contingent Communications Satellite Capacity
Agreement dated as of December 20, 1991 by and between Orion Atlantic and MCN
Sat US, Inc., (iii) Lagardere Groupe SCA (formerly Matra S.A.) under the
Guarantee Agreement dated as of February 19, 1992 between and among Lagardere
Groupe SCA (formerly Matra S.A.), Orion Atlantic and The Chase Manhattan Bank
(National Association), as agent, and (iv) Lagardere Groupe SCA under the
Guaranty Agreement, dated April 2, 1992 between Lagardere Groupe SCA (formerly
Matra S.A.) and Orion Atlantic (including, without limitation, all payment
obligations, guarantees or other credit support obligations under or related to
each such agreement) shall have been terminated and be of no further force or
effect and a termination of guarantee agreements and termination of capacity
agreements, substantially in the form of the exhibits attached to the Exchange
Agreement, in respect of the termination of the obligations of MCN Sat US, Inc.
and MCN Sat Service S.A., respectively, shall be executed and delivered prior to
or concurrently with the Closing.

                  4.6. Subsidiary Guarantee. A Subsidiary Guarantee
substantially in the form of Exhibit B attached hereto, shall be executed and
delivered to each Purchaser by each of the Guarantors. The parties hereto agree
that the Subsidiary Guarantee may, at your sole option, be amended to
incorporate from any subsidiary guarantee provisions for the benefit of the
holders of the Senior Notes, any additional or, in your opinion, more favorable
terms than those appearing in the Subsidiary Guarantee, provided that, in no
event, will the Subsidiary Guarantee become effective prior to the Senior Notes
Reduction Date.

                  4.7. Registration Rights. (i) A Registration Rights Agreement
with respect to the Conversion Shares, the Interest Shares, and certain other
shares specified therein substantially in the form of Exhibit C attached hereto,
shall have been executed by each Purchaser and the Company and (ii) the Company
or ONS shall have obtained all agreements, amendments, consents or waivers, in
form and substance satisfactory to each Purchaser, from the holders of any
registration rights granted pursuant to any prior registration rights agreements
(or any such agreement entered into in connection with the Merger Transaction or

the Financing Transaction) with the Company or ONS as necessary to allow you
(and each other holder of Debentures) their registration rights in accordance
with the terms of the Registration Rights Agreement.

                  4.8. Opinions of Counsel. The Purchasers shall have received a
favorable opinion, dated the Closing Date and satisfactory in form and substance
to the Purchasers, from Hogan & Hartson L.L.P., special counsel for the Company,
which shall opine as to offer and

                                       -4-

<PAGE>



sale of the Debentures. Such opinion shall be deemed to be in form and substance
satisfactory to the Purchasers if the opinion provided is the same as the
opinion provided by Hogan & Hartson L.L.P. to Morgan under the Underwriting
Agreement in connection with the offer and sale of the Senior Notes, except that
the opinion delivered to the Purchasers shall opine as to the Debentures
(including, without limitation, as to the issuance of the Conversion Shares and
Interest Shares) and the Subsidiary Guarantee in addition to or in place of the
Senior Notes and the guarantee thereof and shall refer to the Purchasers and the
Debentures (including the Conversion Shares and Interest Shares), rather than to
Morgan and the Senior Notes, as the context requires. BAe shall also have
received a favorable opinion, dated the Closing Date and satisfactory in form
and substance to BAe, from Hogan & Hartson L.L.P. which shall opine as to the
applicability of Section 16 of the Exchange Act to the receipt of Conversion
Shares and Interest Shares by BAe and the receipt by BAC of stock dividends on,
and shares issued upon conversion of, the Series C Preferred Stock.

                  4.9. Matra Incentive Payments. As a condition to Matra's
obligation to purchase and pay for the Debentures to be purchased by Matra, ONS,
shall, concurrently with the Closing, pay to Matra by wire transfer into a bank
account established by Matra in the United States of America, $13 million of the
payments required to be made under Articles 15.6.1 and 15.6.2 of the Second
Amended and Restated Purchase Contract, dated 26 September 1991, as amended, by
and between Orion Satellite Corporation, as general partner of Orion Atlantic
and Matra.

                  4.10. Senior Notes. The material terms of the Senior Notes, as
set out on the Senior Notes Term Sheet, a copy of which has been furnished to
you, shall not have been amended or waived without your written approval. For
purposes of this Section 4.10, an increase in the size of the Senior Notes
offering shall not constitute an amendment or waiver requiring your written
approval.

                  4.11. Terms of the Merger; Capitalization. The material terms
of the Merger Transaction, as described in the Registration Statement, a copy of
which has been delivered to you and your special U.S. counsel, shall not have
been amended or waived without your written approval. Except for a proposed sale
of ONS Common Stock or Common Stock previously disclosed to you, and except as
specifically contemplated by the Registration Statement and the Senior Notes
Term Sheet, there shall have been no material changes to the capital structure

of either the Company or ONS and no material increase or decrease in the number
of outstanding shares of any class of capital stock of either ONS or the
Company, or in the number of (or terms of) any options, warrants, or other
rights to acquire any shares of any class of capital stock of either ONS or the
Company since January 10, 1997.

                  4.12. HSR Clearance. As a condition to BAe's obligation to
purchase and pay for the Debentures to be purchased by BAe, any waiting period
(including any extensions thereof) applicable to BAC's acquisition of Series C
Preferred Stock pursuant to the Exchange Agreement shall have expired or been
terminated.


                                       -5-

<PAGE>



                  4.13. Investment by Each Purchaser. The purchase of Debentures
by each Purchaser shall be completed concurrently with the purchase of
Debentures by the other Purchaser.

                  4.14.     Termination.

                  (a) No Closing. Notwithstanding anything to the contrary
contained in this Agreement, this Agreement may be terminated and the
transactions contemplated hereby may be abandoned at any time prior to the
Closing:

                            (i)     By the mutual consent of all of the parties;

                            (ii) By a Purchaser at any time in the event of a
                  material breach or material default by the Company in the
                  observance or in the timely performance of any of its
                  obligations hereunder which is not waived by such Purchaser;

                            (iii) By the Company at any time in the event of a
                  material breach or material default by a Purchaser in the
                  observance or in the timely performance of any of such
                  Purchaser's obligations hereunder which is not waived by the
                  Company; or

                            (iv) If the Closing shall not have occurred on or
                  before April 30, 1997, without any further action by you or
                  the Company.

Except as provided in paragraph (iv) above, no termination under this Section
4.14 shall be effective unless and until the terminating party gives written
notice of such termination to the other parties.

                  (b) Failure to Notify. If the Closing shall not actually occur
on any date on which the Closing is scheduled to occur (the "Scheduled Closing
Date") (other than by reason of your failure to purchase Debentures duly

tendered), and the Company shall have failed to notify Coudert Brothers prior to
12:00 p.m., New York City time, on such Scheduled Closing Date that such Closing
has been postponed, the Company shall pay to each Purchaser by wire transfer of
immediately available funds to the bank account designated by such Purchaser (if
such Purchaser incurs any loss of funds or administrative costs, as compensation
for such loss of funds and administrative costs) an amount equal to interest on
the aggregate purchase price for the Debentures to have been purchased by such
Purchaser on such Scheduled Closing Date, at the effective rate of interest
equal to eight and three-quarters percent (8 3/4%) per annum, less the overnight
Federal funds rate, for each day from and including such Scheduled Closing Date
to and including the earlier of the date on which such Closing actually occurs
or the date on which the amount to be paid by such Purchaser as the purchase
price of such Debentures is available to such Purchaser for reinvestment,
provided, that the Company shall pay to such Purchaser in any case not less than
one day's interest at such specified rate.


                                       -6-

<PAGE>



         5. Representations, Warranties and Agreements of the Company and ONS.
Each of ONS and the Company represents, warrants and agrees as follows:

                  5.1. Incorporation, Standing, etc. The Company is a
corporation duly organized, validly existing and in good standing under the laws
of the State of Delaware and has all requisite corporate power and authority to
own and operate its properties, to carry on its business as now conducted and as
presently proposed to be conducted, to enter into this Agreement, to issue and
sell the Debentures, to issue the Conversion Shares and the Interest Shares and
to carry out the terms of this Agreement and the Debentures. The Company has, by
all necessary corporate action, duly authorized the execution and delivery of
this Agreement and of the Debentures and the performance of its obligations
hereunder and under the Debentures (including, without limitation, the issuance
and sale of the Debentures and the issuance of the Conversion Shares and the
Interest Shares).

                  5.2.      Capital Stock.

                  (a) As of January 10, 1997, the authorized capital stock of
ONS consists of 40,000,000 shares of common stock, par value $0.01 per share
("ONS Common Stock"), and 1,000,000 shares of preferred stock, par value $0.01
per share ("ONS Preferred Stock"), of which 10,985,150 shares of ONS Common
Stock, 13,871 shares of ONS Series A 8% Cumulative Redeemable Convertible
Preferred Stock ("ONS Series A Preferred Stock") and 4,298 shares of ONS Series
B 8% Cumulative Redeemable Convertible Preferred Stock ("ONS Series B Preferred
Stock") are duly authorized and validly issued and outstanding, fully paid and
nonassessable. ONS has no other class of stock authorized or outstanding.
Options and warrants to purchase 947,330 shares of ONS Common Stock are
outstanding as of January 10, 1997, and when such options and warrants are
exercised and the prescribed exercise price paid, the shares of ONS Common Stock
issued with respect to such options and warrants will be duly authorized,

validly issued, fully paid and nonassessable. Options to purchase 350,666 shares
of ONS Preferred Stock, the terms of which are to be substantially identical to
the ONS Series A Preferred Stock and the ONS Series B Preferred Stock other than
the conversion price, are outstanding as of January 10, 1997. Except as set
forth above, or in the certificates of designations of the ONS Series A
Preferred Stock and ONS Series B Preferred Stock and related investment
agreements, as of January 10, 1997 there are no existing options, warrants or
rights to purchase or otherwise acquire from ONS Capital Stock of ONS of any
class, no outstanding securities of ONS that are convertible into shares of
Capital Stock of ONS of any class, and no options, warrants or rights to
purchase from ONS any such convertible securities, and ONS has no outstanding
contractual or other obligation to repurchase, redeem or otherwise acquire any
outstanding shares of its Capital Stock.

                  (b) ONS and the Company agree that prior to the Closing Date
there will be no material increase or decrease in the number of outstanding
shares of any class of Capital Stock of either ONS or the Company, or in the
number of (or terms of) any options, warrants, or other rights to acquire any
shares of any class of Capital Stock of either ONS or the Company except in
connection with a proposed sale of ONS Common Stock or Common Stock previously

                                       -7-

<PAGE>



disclosed to you, or as specifically contemplated by the Registration Statement
and the Senior Notes Term Sheet.

                  5.3. Subsidiaries. Attached hereto as Exhibit D is a complete
and correct list of the Subsidiaries of the Company and ONS, which Exhibit D
correctly sets forth as to each Subsidiary as of January 31, 1997 (a) its name,
(b) the jurisdiction of its organization and the jurisdictions, if any, in which
it is qualified as a foreign corporation or foreign partnership and (c) the
percentage of its issued and outstanding shares of common stock, shares of
beneficial interest or general and limited partnership interests owned by the
Company, ONS or another Subsidiary. Each corporate Subsidiary is a corporation
duly organized, validly existing and in good standing under the laws of the
jurisdiction of its incorporation, and each limited partnership Subsidiary is
duly formed, validly existing and in good standing under the laws of its
jurisdiction of organization. Each Subsidiary has all requisite power and
authority to own and operate its properties and to carry on its business as now
conducted and as presently proposed to be conducted. All the outstanding equity
interests or partnership interests of, or shares of capital stock of, or shares
of beneficial interest in, each Subsidiary are duly authorized, validly issued,
fully paid and nonassessable, and all such equity interests, partnership
interests or shares indicated in Exhibit D as owned by the Company, ONS or by
another Subsidiary are so owned beneficially and of record by the Company or
such other Subsidiary, free and clear, except as described in the Registration
Statement, of any Lien. Upon the completion of the Merger Transaction, Exhibit D
shall be amended to include ONS as a Wholly Owned Subsidiary of the Company.

                  5.4. Qualification. The Company and ONS are, and each of the

Subsidiaries listed on Exhibit D is, duly qualified and in good standing as a
foreign corporation or partnership authorized to do business in the
jurisdictions indicated with respect to it in Exhibit D. Failure of the Company,
ONS or any of their respective Subsidiaries to so qualify in any other
jurisdiction would not, in any case or in the aggregate, have a Material Adverse
Effect.

                  5.5. Business; Financial Statements. The Company has delivered
to you complete and correct copies of (a) the annual report to stockholders of
ONS for the fiscal year ended December 31, 1995 (the "Annual Report"), (b) the
annual report to the Commission of ONS on Form 10-K for the fiscal year ended
December 31, 1995 (the "10-K") and (c) the report to the Commission on ONS for
the fiscal quarter ended September 30, 1996 (the "10-Q"). The Annual Report and
the 10-K correctly describe, as of their respective dates, the business then
conducted by ONS and its Subsidiaries and proposed to be conducted by the
Company, ONS and the Subsidiaries. The 10-K includes the consolidated financial
statements of ONS and the Subsidiaries for each of the fiscal years ended
December 31, 1994 and 1995 accompanied by the report thereon of Ernst & Young
LLP, certified public accountants. All of said financial statements (including
in each case the related schedules and notes) fairly present in all material
respects the consolidated financial position of ONS and the Subsidiaries as of
the respective dates specified in the 10-K and the consolidated results of their
operations and cash flows for the respective periods so specified and have been
prepared in accordance with GAAP consistently

                                       -8-

<PAGE>



applied throughout the periods involved except as set forth in the notes thereto
and subject in the case of unaudited financial statements to normal recurring
audit adjustments.

                  5.6. Solvency. ONS and its Subsidiaries, considered as one
enterprise, are Solvent and immediately after the Closing Date, the Company and
its Subsidiaries, considered as one enterprise, will be Solvent.

                  5.7. Authorization of Agreement. This Agreement has been duly
authorized, executed and delivered by each of the Company and ONS.

                  5.8. Authorization of Common Stock. Upon issuance and delivery
of the Debentures in accordance with this Agreement, the Debentures will be
convertible at the option of the holders thereof for shares of Common Stock in
accordance with the terms of the Debentures and this Agreement; the Conversion
Shares and the Interest Shares have been duly and validly authorized and
reserved for issuance upon payment of interest and upon conversion by all
necessary corporate action of the Company, and such shares, when issued upon
such conversion or as a payment of interest in accordance with the terms of the
Debentures and this Agreement, will be duly and validly issued and will be fully
paid and non-assessable; no holder of such shares will be subject to personal
liability solely by reason of being such a holder; and the issuance of such
shares upon conversion or as a payment of interest in accordance with the terms

of the Debentures and this Agreement will not be subject to the preemptive or
other similar rights of any security holder of the Company arising by operation
of law, or under the Certificate of Incorporation or bylaws of the Company or
under any agreement to which the Company is a party or by which the Company is
bound.

                  5.9. Absence of Defaults and Conflicts. None of the Company,
ONS or any of their respective Subsidiaries are in violation of their respective
certificates of incorporation, bylaws or other charter documents or is in
default in the performance or observance of any material obligation, agreement,
covenant or condition contained in any contract, indenture, mortgage, loan
agreement, note, lease or other instrument to which any of them is a party or by
which any of them may be bound, or to which any of the property or assets of the
Company, ONS or any of their Subsidiaries is subject (collectively, "Agreements
and Instruments") except for such defaults that would not result in a Material
Adverse Effect; and the execution, delivery and performance of this Agreement
and any other Agreement or Instrument entered into or issued or to be entered
into or issued by the Company, ONS or any of their respective Subsidiaries in
connection with the transactions contemplated hereby or thereby, and the
consummation of the transactions contemplated herein or therein (including the
issuance and sale of the Debentures, the use of the proceeds from the sale of
the Debentures and the issuance of the Conversion Shares and Interest Shares)
and compliance by the Company with its obligations hereunder and thereunder,
have been duly authorized by all necessary corporate action and do not and will
not, whether with or without the giving of notice or passage of time or both,
conflict with or constitute a breach of, or default or Repayment Event (as
defined below) under, or result in the creation or imposition of any lien,
charge or encumbrance upon any property or assets of the Company, ONS or any of
their respective Subsidiaries pursuant to the Agreements

                                       -9-

<PAGE>



and Instruments, except for such conflicts, breaches, defaults, Repayment Events
or liens, charges or encumbrances that would not result in a Material Adverse
Effect, nor will such action result in any violation of the provisions of the
Certificate of Incorporation, bylaws or other charter documents of the Company,
ONS or any of their respective Subsidiaries or any applicable law, statute,
rule, regulation, judgment, order, writ or decree of any government, government
instrumentality or court, domestic or foreign, having jurisdiction over the
Company, ONS or any of their respective Subsidiaries or any of their assets or
properties, except for such violations of law, statutes, rules, regulations,
judgments, orders, writs or decrees that would not result in a Material Adverse
Effect. As used herein, a "Repayment Event" means any event or condition which
gives the holder of any note, debenture or other evidence of indebtedness (or
any Person acting on such holder's behalf) the right to require the repurchase,
redemption or repayment of all or a portion of such indebtedness by the Company,
ONS or any of the Subsidiaries.

                  5.10. Absence of Labor Dispute. No labor dispute with the
employees of the Company, ONS or any of the Subsidiaries exists or, to the best

of the Company's knowledge, is threatened and the Company has not received
notice of any existing or threatened labor disturbance by the employees of any
of the principal suppliers, manufacturers, customers or contractors of the
Company, ONS or any of their respective Subsidiaries, which, in either case, may
reasonably be expected to result in a Material Adverse Effect.

                  5.11. Absence of Proceedings. There is no action, suit or
proceeding before or by any court or governmental agency or body, domestic or
foreign, now pending or, to the best of the Company's knowledge, threatened,
against or affecting the Company, ONS or any of their respective Subsidiaries or
any of their respective officers or directors in their capacity as such or any
of their respective property or assets, that is required to be disclosed in the
Registration Statement (other than as disclosed therein), or which might
reasonably be expected to result in any Material Adverse Effect, or which might
reasonably be expected to have a Material Adverse Effect on the properties or
assets thereof or the consummation of the Financing Transaction, the
transactions contemplated by this Agreement or the transactions contemplated in
the Registration Statement, or the performance by the Company, ONS or any of
their respective Subsidiaries of any obligation hereunder or thereunder; the
aggregate of all pending legal or governmental proceedings to which the Company,
ONS or any of their respective Subsidiaries is a party or of which any of their
respective property or assets is the subject which are not described in the
Registration Statement, including ordinary routine litigation incidental to the
business, could not reasonably be expected to result in a Material Adverse
Effect. Without limiting the foregoing, except as otherwise set forth in the
Registration Statement and in Schedule II hereto, there are no legal or
governmental proceedings, including rulemaking proceedings of general
applicability in the industry or industries in which the Company, ONS or any of
their Subsidiaries operate, by or before the Federal Communications Commission
(the "FCC"), any state public utility commission or similar state governmental
agency ("PUC") or any international body formed by treaty that is responsible
for coordinating and registering orbital slots to satellites, including but not
limited to, the International Telecommunication Union ("ITU"), now pending or,
to the Company's best knowledge, threatened or contemplated, which

                                      -10-

<PAGE>



in each case might reasonably be expected to result in any Material Adverse
Effect. In addition, all applications, reports and other filings required to be
filed through the Execution Date with the FCC, the PUC, the ITU or any other
governmental or international authority, have been duly and timely filed and all
such applications, reports and other filings required to be filed by the Closing
Date will have been filed prior to the Closing Date.

                  5.12. Possession of Licenses and Permits. The Company, ONS and
the Subsidiaries possess such permits, certificates, licenses, approvals,
consents, orders and other authorizations (collectively, "Governmental
Licenses") issued by the appropriate Federal, state, local or foreign regulatory
agencies or bodies necessary to conduct the business now operated by them,
except for such permits, certificates, licenses, approvals, consents, orders and

other authorizations the absence of which would not have a Material Adverse
Effect; the Company, ONS and their respective Subsidiaries are in compliance
with the terms and conditions of all such Governmental Licenses, except where
the failure so to comply would not, individually or in the aggregate, have a
Material Adverse Effect; all of the Governmental Licenses are valid and in full
force and effect, except where the invalidity of such Governmental Licenses or
the failure of such Governmental Licenses to be in full force and effect would
not have a Material Adverse Effect; and none of the Company, ONS or any of their
respective Subsidiaries has received any notice of proceedings relating to the
revocation, withdrawal, cancellation, modification, suspension or non-renewal of
any such Governmental Licenses which, individually or in the aggregate, if the
subject of an unfavorable decision, ruling or finding, would result in a
Material Adverse Effect.

                  5.13. Environmental Laws. None of the Company, ONS or any of
their respective Subsidiaries is in violation of any Federal, state, local or
foreign statute, law, rule, regulation, ordinance, code, policy or rule of
common law and any judicial or administrative interpretation thereof, including
any judicial or administrative order, consent, decree or judgment, relating to
pollution or protection of human health, the environment (including, without
limitation, ambient air, surface water, groundwater, land surface or subsurface
strata) or wildlife, including, without limitation, laws and regulations
relating to the release or threatened release of chemicals, pollutants,
contaminants, wastes, toxic substances, hazardous substances, petroleum or
petroleum products (collectively, "Hazardous Materials") or to the manufacture,
processing, distribution, use, treatment, storage, disposal, transport or
handling of Hazardous Materials (collectively, "Environmental Laws"), except for
such violations as would not, individually or in the aggregate, result in a
Material Adverse Effect. None of the Company, ONS or any of their respective
Subsidiaries has received any notice from any governmental authority or third
party of an asserted claim under any Environmental Law. The Company, ONS and
their respective Subsidiaries have all permits, authorizations and approvals
required under any applicable Environmental Laws and are each in compliance with
their requirements, except for such permits, authorizations and approvals the
absence of which would not, individually or in the aggregate, result in a
Material Adverse Effect. There are no pending or, to the Company's knowledge,
threatened administrative, regulatory or judicial actions, suits, demands,
demand letters, claims, liens, notices of noncompliance or violation,
investigation or proceedings relating to any Environmental Law against the
Company, ONS or any of their

                                      -11-

<PAGE>



respective Subsidiaries, except for such actions, suits, demands, demand
letters, claims, liens, notices of noncompliance or violation, investigation or
proceedings which if decided adversely to the Company, ONS or any of their
respective Subsidiaries would not, individually or in the aggregate, result in a
Material Adverse Effect. To the best of the Company's knowledge, there are no
events or circumstances that might reasonably be expected to form the basis of
any order for clean-up or remediation, or an action, suit or proceeding by any

private party or governmental body or agency, against or affecting the Company,
ONS or any of their respective Subsidiaries relating to any Hazardous Materials
or the violation of any Environmental Laws.

                  5.14. No Violations of Laws. None of the Company, ONS or any
of their respective Subsidiaries has violated any foreign, Federal or state law
relating to the discrimination in the hiring, promotion or pay of employees nor
any applicable Federal or state wages and hours laws nor any other Federal or
State law concerning the conditions or the terms of employment of employees by
an employer, nor any provisions of ERISA or the rules and regulations
promulgated thereunder nor any provisions of the U.S. Communications Act of
1934, as amended, nor the rules or regulations promulgated thereunder, nor any
applicable state law or regulation concerning intra-state telecommunications nor
any foreign law or regulation concerning international communications (such
state and foreign laws and regulations, along with the U.S. Communications Act
of 1934, as amended, and the regulations thereunder being referred to herein as
the "Communications Laws"), except for such violations as, individually or in
the aggregate, will not have a Material Adverse Effect.

                  5.15. Internal Accounting Controls. The books, records and
accounts of the Company, ONS and their respective Subsidiaries accurately and
fairly reflect, in all material respects, in reasonable detail, the transactions
in and dispositions of the assets of the Company, ONS and their respective
Subsidiaries. The Company, ONS and each of their respective Subsidiaries
maintain a system of internal accounting controls sufficient to provide
reasonable assurance that (i) transactions are executed in accordance with
management's general or specific authorizations; (ii) transactions are recorded
as necessary to permit preparation of financial statements in conformity with
GAAP and to maintain asset accountability; (iii) access to assets is permitted
only in accordance with management's general or specific authorization; and (iv)
the recorded amount for assets is compared with the existing assets at
reasonable intervals and appropriate action is taken with respect to any
differences.

                  5.16. Tax Returns and Payments. The Company, ONS and each of
their respective Subsidiaries have filed all income tax returns required by law
to be filed by them and have paid all taxes shown to be due and payable on such
returns and all other taxes, assessments, fees and other governmental charges
levied upon them and their respective properties, assets, income and franchises
which are due and payable, to the extent such taxes and assessments have become
due and payable and before they have become delinquent, except for any taxes and
assessments (i) the amount of which is not individually or in the aggregate
Material or (ii) the amount, applicability or validity of which is currently
being contested in good faith by appropriate proceedings and with respect to
which the Company, ONS or any of their respective Subsidiaries, as the case may
be, has established adequate reserves in accordance with

                                      -12-

<PAGE>



GAAP. The charges, accruals and reserves on the books of the Company, ONS and

any of their respective Subsidiaries in respect of Federal, state and foreign
income taxes for all fiscal periods are adequate in the reasonable opinion of
the Company and, to the best of the Company's knowledge, there are no additional
assessments for such periods or any basis therefor.

                  5.17. Indebtedness. None of the Company, ONS or any of their
respective Subsidiaries is in default and no waiver of default is currently in
effect, in the payment of any principal, interest or premium on any Indebtedness
of the Company, ONS or any such Subsidiary and no event or condition exists with
respect to any Indebtedness of the Company, ONS or any such Subsidiary the
outstanding principal amount of which exceeds $1,000,000 that would permit (or
that with notice or the lapse of time, or both, would permit) one or more
Persons to cause such Indebtedness to become due and payable before its stated
maturity or before its regularly scheduled dates of payment.

                  5.18. Title to Properties; Liens. The Company, ONS and their
respective Subsidiaries each have good and marketable title to all of their
respective properties and assets, including such properties and assets which are
reflected in the financial statements as at December 31, 1995 referred to in
Section 5.5 (except for such properties and assets disposed of since such date
in the ordinary course of business and except as set forth in the Registration
Statement), free and clear of all Liens except as set forth in the Registration
Statement, except for minor imperfections of title and encumbrances, if any,
which do not materially impair the use thereof in the operation of the business
of the Company, ONS or any of their respective Subsidiaries and except for
Permitted Liens.

                  5.19. Patents, Trademarks, Authorizations, etc. The Company,
ONS and their respective Subsidiaries own, possess or have the right to use
(without any known conflict with the rights of others) all patents, trademarks,
service marks, trade names, copyrights, licenses and authorizations which are
necessary to the conduct of their respective businesses as conducted on the date
hereof and which the failure to own, possess or have the right to use might
result in a Material Adverse Effect.

                  5.20. Governmental Consents; Exercise of Voting Rights, etc.
(a) None of the nature of the Company, ONS or of any of their respective
Subsidiaries, nor any of their respective businesses or properties, nor any
relationship between the Company, ONS or any such Subsidiary and any other
Person, nor any circumstance in connection with the offer, issue, sale or
delivery of the Debentures, is such as to require any consent, approval or
authorization of, or any notice to, of filing, registration or qualification
with, any court or administrative or governmental body by or on behalf of the
Company, ONS or any Subsidiary in connection with the execution and delivery of
this Agreement or the offer, issue, sale or delivery of the Debentures, the
Interest Shares and the Conversion Shares or fulfillment of, or compliance with,
the terms and provisions of this Agreement or of the Debentures, except for (1)
filings of reports pursuant to Section 13 or 15(d) of the Exchange Act, (2)
filings under state securities or Blue Sky laws, (3) filings under the HSR Act.


                                      -13-

<PAGE>




         (b) No Applicable Law and no provision of the certificate of
incorporation, bylaws or other governing documents of the Company, ONS or any of
their respective Subsidiaries is such as to require or would give rise to any
limitation of any type on your right to vote (or consent with respect to) any
securities of ONS or the Company owned by you as of the Execution Date or that
will be owned by you as a result of (A) the Merger Transaction, (B) consummation
of the transactions contemplated by the Exchange Agreement or (C) the Closing
under this Agreement (including any Conversion Shares or Interest Shares
received hereunder).

                  5.21. Offer of Debentures. Neither ONS nor the Company has
either directly or indirectly or through an agent directly or indirectly offered
the Debentures or any part thereof or any similar securities for sale to, or
solicited any offer to buy any of the same from, or otherwise approached or
negotiated in respect thereof with, anyone other than you. None of ONS, the
Company nor anyone authorized or employed to act on its behalf of either of them
has taken or will take any action which would subject the issuance and sale of
the Debentures to the provisions of Section 5 of the Securities Act or to the
registration or qualification requirements of any securities or Blue Sky law of
any applicable jurisdiction.

                  5.22. Federal Reserve Regulations. Neither the Company nor any
of its Subsidiaries will, directly or indirectly, use any of the proceeds of the
sale of the Debentures for the purpose of purchasing or carrying any "margin
security" within the meaning of Regulation G of the Board of Governors of the
Federal Reserve System (12, C.F.R. 207, as amended), or any "security that is
publicly-held" within the meaning of Regulation T of such Board (12 C.F.R. 220,
as amended), or otherwise take or permit to be taken any action which would
involve a violation of such Regulation G or Regulation T or Regulation X (12
C.F.R. 224, as amended) or any other regulation of such Board. No Indebtedness
being reduced or retired out of the proceeds of the sale of the Debentures, if
any, was incurred for the purpose of purchasing or carrying any "margin
security" within the meaning of such Regulation G or any "security that is
publicly-held" within the meaning of such Regulation T. None of the Company, ONS
or any of their Subsidiaries owns or has any present intention of acquiring
directly or indirectly any such margin security or any such security that is
publicly-held.

                  5.23. Investment Company Act. The Company is not, and upon the
issuance and sale of the Debentures as herein contemplated and the application
of the net proceeds therefrom will not be, an "investment company" or an entity
"controlled" by an "investment company" as such terms are defined in the
Investment Company Act of 1940, as amended (the "Investment Company Act"), nor
is the Company an "open-ended investment trust," "unit investment trust" or
"face-amount certificate company" that is or is required to be registered under
Section 8 of the Investment Company Act.

                  5.24. Public Utility Holding Company Act. The Company is not a
"holding company," or a "subsidiary company" of a "holding company," or an
"affiliate" of a "holding company" or of a "subsidiary company" of a "holding
company," as such terms are defined in the Public Utility Holding Company Act of

1935, as amended.


                                      -14-

<PAGE>



                  5.25. Compliance with ERISA. (a) The Company, ONS and each
ERISA Affiliate have operated and administered each Plan in compliance with all
applicable laws except for such instances of noncompliance as have not resulted
in and could not reasonably be expected have in a Material Adverse Effect. None
of the Company, ONS or any ERISA Affiliate has incurred any liability pursuant
to Title I or IV of ERISA or the penalty or excise tax provisions of the Code
relating to employee benefit plans (as defined in Section 3 of ERISA), and no
event, transaction or condition has occurred or exists that could reasonably be
expected to result in the incurrence of any such liability by the Company, ONS
or any ERISA Affiliate, or in the imposition of any Lien on any of the rights,
properties or assets of the Company, ONS or any ERISA Affiliate, in either case
pursuant to Title I or IV of ERISA or to such penalty or excise tax provisions
or to Section 401(a)(29) or 412 of the Code, other than such liabilities or
Liens as would not be individually or in the aggregate Material.

                  (b) The present value of the aggregate benefit liabilities
under each of the Plans (other than Multiemployer Plans), determined as of the
end of such Plan's most recently ended plan year on the basis of the actuarial
assumptions specified for funding purposes in such Plan's most recent actuarial
valuation report, did not exceed the aggregate current value of the assets of
such Plan allocable to such benefit liabilities. The term "benefit liabilities"
has the meaning specified in Section 4001 of ERISA and the terms "current value"
and "present value" have the meaning specified in Section 3 of ERISA.

                  (c) The Company, ONS and the ERISA Affiliates have not
incurred withdrawal liabilities (and are not subject to contingent withdrawal
liabilities) under Section 4201 or 4204 of ERISA in respect of Multiemployer
Plans that individually or in the aggregate are Material.

                  (d) The execution and delivery of this Agreement and the
issuance and sale of the Debentures hereunder will not involve any transaction
that is subject to the prohibitions of Section 406 of ERISA or in connection
with which a tax could be imposed pursuant to Section 4975(c)(1)(A)-(D) of the
Code. The representation by the Company and ONS in the first sentence of this
Section 5.25(d) is made in reliance upon and subject to (i) the accuracy of the
representation in Section 6.2 by each Purchaser as to the sources of the funds
to be used to pay the purchase price of the Debentures to be purchased by such
Purchaser and (ii) the assumption, made solely for the purpose of making such
representation, that Department of Labor Interpretive Bulletin 75-2 with respect
to prohibited transactions remains valid in the circumstances of the
transactions contemplated herein.

                  5.26. Disclosure. The Registration Statement, including the
financial statements included therein and any document incorporated therein by
reference, complies or will comply as to form with all applicable provisions of

the Securities Act in all material respects. As of its effective date, the
Registration Statement does not or will not contain any untrue statements of a
material fact or omit to state a material fact necessary in order to make the
statements contained therein not misleading. This Agreement and the other
documents certificates, instruments or reports delivered to you under this
Agreement, taken as a whole, do not contain

                                      -15-

<PAGE>



any untrue statements of material facts or omit to state material facts
necessary in order to make the statements contained herein or therein, in the
light of the circumstances under which they were made, not misleading. There is
no fact known to either ONS or the Company which has had a Material Adverse
Effect through the Execution Date or in the future (so far as the Company and
ONS can now reasonably foresee and excluding the effect of general economic and
industry conditions) may have a Material Adverse Effect which has not been or
will not be set forth or reflected in the Registration Statement. The
representations contained in this Section 5.26 shall also apply to any
amendments to the Registration Statement and to the registration statement
declared effective by the Commission with respect to the Financing Transaction
and to any amendments to any such registration statement.

                  5.27. HSR Act Filings. The Company hereby agrees to promptly
make such filings or other submissions under the HSR Act as may be required with
respect to the conversion of any Debenture, the payment of any Interest Shares
or with respect to the redemption or repurchase of any Debenture or in
connection with any Mandatory Sale of Underlying Shares. The Company hereby
agrees to use its best efforts to respond to requests for additional information
relating to such filings or submissions. Exercise by the Company of its rights
under Section 11 of this Agreement or otherwise hereunder shall be subject to
compliance with the HSR Act as applicable.

                  5.28. Certificate of Incorporation (a) The Company hereby
agrees that, notwithstanding its rights under its Certificate of Incorporation,
it shall not exercise whatever rights it may have under Article Tenth of its
Certificate of Incorporation (as presently in effect and as the same may be
amended, supplemented or otherwise changed, "Article Tenth"), to redeem (i) any
Debentures, (ii) any Conversion Shares, (iii) any Interest Shares, (iv) any
share of Series C Preferred Stock, (v) any securities received as stock
dividends or redemption payments on any share of Series C Preferred Stock
pursuant to the Certificate of Designations, Rights and Preferences with respect
to the Series C Preferred Stock (the "Series C Designation") or (vi) any
securities received upon any conversion of any share of Series C Preferred Stock
(collectively, the "Subject Securities") held by you unless (x) you shall have
received a copy of an opinion addressed to the Company, reasonably acceptable to
you, of Verner, Liipfert, Bernard, McPherson and Hand Chartered or other U.S.
regulatory counsel reasonably acceptable to you, to the effect that such
redemption is necessary to prevent a loss or secure reinstatement of a franchise
of the type specified in Article Tenth and (y) you have received an Officers'
Certificate to the effect that such loss or failure to secure such reinstatement

would have a Material Adverse Effect. The Company agrees to exercise its right
of redemption only to the minimum extent necessary to avoid such loss or to
secure such reinstatement. The Company shall pay the redemption price under
Article Tenth all in cash or, to the extent permitted under Article Tenth and if
another form of consideration is provided with respect to redemptions under this
Agreement or the Series C Designation, as applicable, in such other form. The
Company presently has no knowledge of any grounds for requiring any redemption
under Article Tenth with respect to you.


                                      -16-

<PAGE>



                  (b) If the Company shall have exercised its right of
redemption pursuant to Article Tenth with respect to any Subject Securities
that, immediately prior to such redemption, were held by you, in addition to
having paid you the redemption price under Article Tenth, it shall and hereby
agrees to pay you thereupon, solely and specifically in consideration of your
having entered into this Agreement, the positive difference, if any, of (i) the
highest dollar value (adding cash and the value of any securities received) you
would have received with respect to the Subject Securities had they been
redeemed under applicable provisions of this Agreement or the Series C
Designation, as the case may be, as at the date they were instead redeemed under
Article Tenth less (ii) the dollar value (adding cash and the value of any
securities received) actually received by you as a result of any redemption
pursuant to Article Tenth. For purposes of this Section 5.28, the "value of any
securities received" shall be equal to the "Closing Price" of such securities as
"Closing Price" is defined in Article Tenth. The payment to be received by you
under and pursuant to this Section 5.28(b) with respect to any Subject
Securities that have been redeemed under Article Tenth will be either (i) all in
cash or (ii) otherwise in the form provided with respect to redemptions under
this Agreement or the Series C Designation, as applicable, for the Subject
Securities redeemed. Notwithstanding anything in this Agreement to the contrary,
the provisions of this Section 5.28 shall survive until the first date after the
Closing Date as of which you do not own any Subject Security.

         6.       Representations, Warranties and Agreements of Purchasers.

                  6.1. Investment Representations. Each Purchaser represents and
warrants (for itself and not the other Purchaser) that it is purchasing the
Debentures for its own account for investment and not with a view to the resale
or distribution of the Debentures or any part thereof or any Conversion Shares
or Interest Shares, and that such Purchaser has no present intention of
distributing any of the same; provided, however, that the disposition of such
Purchaser's property shall at all times be within such Purchaser's control. Each
Purchaser understands that the Debentures have not been registered under the
Securities Act, and that upon issuance the Conversion Shares and the Interest
Shares will not be registered under the Securities Act, and that the Debentures,
the Conversion Shares and the Interest Shares may be resold only if registered
pursuant to the provisions of the Securities Act or if an exemption from
registration is available.


                  6.2. ERISA. Each Purchaser represents (for itself and not the
other Purchaser) that it is not acquiring the Debentures or any interest therein
with assets allocated to any separate account maintained by it in which any
employee benefit plan (or its related trust) has any interest. As used in this
Section 6.2, "separate account" and "employee benefit plan" shall have the
respective meanings assigned thereto in Section 3 of ERISA.

                  6.3. HSR Act Filings. You hereby agree to promptly make such
filings or other submissions under the HSR Act as may be required with respect
to the conversion of any Debenture, the receipt of any Interest Shares or with
respect to the redemption or repurchase of any Debenture or in connection with
any Mandatory Sale of Underlying Shares. You hereby agree to use your best
efforts to respond to requests for additional information relating to such

                                      -17-

<PAGE>



filings or submissions. Exercise by you of your rights under Section 11 of this
Agreement or otherwise hereunder shall be subject to compliance with the HSR Act
as applicable.

         7.       Accounting; Financial Statements; Other Information.

                  7.1. Accounting; Financial Statements and Other Information.
The Company will maintain, and will cause each of its Subsidiaries to maintain,
a system of accounting established and administered in accordance with GAAP. The
Company will deliver (in duplicate) to you, so long as you shall hold any
Debentures:

                            (a) as soon as practicable, and, in any case, within
         ninety (90) days after the close of each fiscal year, two (2) copies of
         the consolidated balance sheet of the Company and its Subsidiaries
         setting forth their consolidated financial condition as at the end of
         such fiscal year, together with consolidated statements of income,
         stockholders' equity and cash flows of the Company and its Subsidiaries
         for such fiscal year, all in reasonable detail, such consolidated
         balance sheet and statements of income, stockholders' equity and cash
         flows to be accompanied by an opinion with respect thereto of
         independent public accountants of recognized national standing, who may
         be the present regular auditors of the books of the Company, which
         opinion (i) shall state that such financial statements present fairly
         the consolidated financial position and the consolidated results of
         operations and cash flows of the Company, in conformity with GAAP
         applied on a consistent basis during the period (except for changes in
         application in which such accountants concur), and that the examination
         of such accountants in connection with such financial statements has
         been made in accordance with generally accepted auditing standards and,
         accordingly, included such tests of the accounting records and such
         other auditing procedures as were considered necessary in the
         circumstances, or (ii) shall, using appropriate language that at the

         time shall have been adopted by the American Institute of Certified
         Public Accountants and generally employed by the accounting profession,
         certify in substance that such financial statements present fairly the
         consolidated financial position and the consolidated results of
         operations and cash flows of the Company, in conformity with GAAP
         applied on a consistent basis during the period (except for changes in
         application in which such accountants concur), and that the examination
         of such accountants in connection with such financial statements has
         been made in accordance with generally accepted auditing standards,
         and, accordingly, included such tests of the accounting records and
         such other auditing procedures as were considered necessary in the
         circumstances; provided that, the delivery within the time period
         specified above (or, if later, within five (5) days of timely filing
         with the Commission) of the Company's Annual Report on Form 10-K
         (together with the Company's annual report to shareholders, if any,
         prepared pursuant to Rule 14a-3 under the Exchange Act) for any fiscal
         year prepared in compliance with the requirements therefor and filed
         with the Commission shall be deemed to satisfy the requirements of this
         Section 7.1(a) for such fiscal year;


                                      -18-

<PAGE>



                            (b) as soon as practicable and, in any case, within
         sixty (60) days after the end of the first, second and third quarterly
         accounting periods in each fiscal year, an unaudited consolidated
         balance sheet of the Company and its Subsidiaries as at the end of such
         accounting period, and unaudited consolidated statements of income,
         stockholders' equity and cash flows of the Company and its Subsidiaries
         for such period and for the fiscal year to date, setting forth in each
         case in comparative form the figures for the corresponding periods a
         year earlier, all in reasonable detail, prepared and certified by the
         Treasurer or the Controller or any Vice President of the Company as
         presenting fairly such financial condition and results of operations,
         subject to changes resulting from year-end audit adjustments; provided
         that, delivery within the time period specified above (or, if later,
         within five (5) days of timely filing with the Commission) of copies of
         the Company's Quarterly Report on Form 10-Q for any quarterly
         accounting period prepared in compliance with the requirements thereof
         and filed with the Commission shall be deemed to satisfy the
         requirements of this Section 7.1(b) for such quarterly accounting
         period;

                            (c) promptly after the submission thereof to the
         Company, copies of all communications prepared by independent
         accountants regarding matters of material weakness of internal
         accounting controls submitted to the Company's senior management, its
         Board of Directors or the audit committee of its Board of Directors, as
         contemplated by American Institute of Certified Public Accountants
         Statement of Auditing Standards No. 60;


                            (d) promptly upon distribution thereof, copies of
         all such financial or other statements, including proxy statements and
         reports, as the Company shall send to the holders of its Common Stock
         or the holders of the Senior Notes;

                            (e) promptly after filing thereof, copies of all
         regular and periodic reports and registration statements which the
         Company may file with the Commission, other than registration
         statements on Form S-8;

                            (f) promptly upon receipt thereof, copies of any
         notices received from any administrative official or agency relating to
         any order, ruling, statute or other law or information which might have
         or cause a Material Adverse Effect; and

                            (g) promptly upon request therefor, such information
         as to the business and properties of the Company as you may from time
         to time reasonably request.

Notwithstanding any other provision of this Section 7.1, the Company will be
required to deliver to BAe and Matra only, and not to any other holder of
Debentures, the materials specified in paragraphs (a), (b), (c), (f) and (g).
The Company will deliver (in duplicate) to each holder of Debentures (other than
BAe and Matra) the materials specified in paragraphs (d) and (e).


                                      -19-

<PAGE>



                  7.2. Company Certificate. Each set of financial statements
delivered pursuant to Section 7.1(a) or Section 7.1(b) will be accompanied by a
certificate, signed by one of the Responsible Officers, stating that a review of
the affairs and activities of the Company during the applicable period has been
made by authorized employees of the Company and that, to the knowledge and
belief of such officer, there did not exist at any time during such period any
condition or event which constitutes an Event of Default under any of the
provisions of this Agreement or the Debentures; provided, however, that if to
the knowledge of such officer any such Event of Default shall have occurred,
such certificate shall so specify and shall state whether such Event of Default
has been cured or is continuing and, if continuing, what steps the Company
proposes to take to cure such Event of Default and the time necessary to cure
such Event of Default.

                  7.3. Accountant's Certificate. Each set of annual financial
statements delivered pursuant to Section 7.1(a) will be accompanied by a report
of the independent public accountants who have certified or reported on such
financial statements, stating that in making their examination necessary to
express an opinion on such financial statements, such accountants have obtained
no knowledge of any condition or event which constitutes an Event of Default or
a Potential Event of Default or, if such accountants have any such knowledge

that any such condition or event then exists, specifying the nature and period
of existence thereof. Each such report may in addition state that such
examination was not directed primarily toward obtaining knowledge of any such
condition or event referred to in the preceding sentence.

         8.       Inspection.

                            (a) Pre-Closing Access. From the Execution Date
         through the Closing Date, the Company and ONS shall each: (i) upon
         reasonable prior notice, permit each Purchaser and its authorized
         representatives, counsel, accountants and agents to have reasonable
         access to its properties, records and documents, and (ii) furnish to
         each Purchaser and its authorized representatives, counsel, accountants
         and agents such financial records and other documents with respect to
         the Company, ONS or any Subsidiary as such Purchaser may reasonably
         request; provided, however, that in no event shall the Company be
         obligated to comply with any of the foregoing if such compliance will
         give any Person access to any information which the Company, ONS or any
         Subsidiary is required by contract or otherwise to keep confidential;
         and provided, further, that with respect to such confidential
         information, the Company or ONS shall, at its expense, upon a
         Purchaser's specific request, use its best efforts to seek the consent
         of such Persons as may be necessary to permit the requesting party
         access to such information without violating the confidential nature
         thereof.

                            (b) Post-Closing Access. While you hold any
         Debentures, your representative or representatives may visit and
         inspect any of the properties of the Company or any of its Subsidiaries
         as follows:


                                      -20-

<PAGE>



                                    (i) No Default. If no Potential Event of
                  Default or Event of Default exists, then at your expense and
                  upon reasonable prior notice to the Company, you may visit the
                  principal executive offices of the Company to discuss the
                  affairs, finances and accounts of the Company and its
                  Subsidiaries with the Company's officers, and, with the
                  consent of the Company (which consent will not be unreasonably
                  withheld), visit the other offices and properties of the
                  Company and each Subsidiary, all at such reasonable times and
                  as often as may be reasonably requested in writing; and

                                    (ii) Default. If a Potential Event of
                  Default or Event of Default exists, then at the expense of the
                  Company you may visit and inspect any of the offices or
                  properties of the Company or any Subsidiary to examine all
                  their respective books of account, records, reports and other

                  papers, to make copies and extracts therefrom, and to discuss
                  their respective affairs, finances and accounts with their
                  respective officers and independent public accountants (and by
                  this provision the Company authorizes said accountants to
                  discuss the affairs, finances and accounts of the Company and
                  its Subsidiaries), all at such reasonable times and as often
                  as may be requested.

The rights set forth in this Section 8(b) are granted to BAe and Matra only and
not to any other holders of Debentures.

         9. Confidential Treatment. You agree that any information concerning
the Company, ONS or any of their respective Subsidiaries obtained by you under
the provisions of Section 7 or 8 or which was furnished to you in connection
with the negotiation of the transactions contemplated hereby and which in any
case is not contained in a report or other document filed with the Commission
(and which is not afforded confidential treatment by the Commission or such
other agency), distributed by ONS and, after consummation of the Merger
Transaction, by the Company to its public stockholders or otherwise available to
the public generally and which is or was designated by the Company in writing as
confidential, will, to the extent permitted by law or legal process, be treated
confidentially by you and will not be distributed or otherwise made available by
you to any Person, other than your employees or your authorized agents or
representatives; provided, however, that you may provide any such information to
any governmental agency or other Person to which you are required by law or
legal process to provide such information.

         10. ERISA. The Company will deliver (in duplicate) to you, so long as
you shall hold any Debenture, and to each other holder of the outstanding
Debentures, promptly, and in any event within five (5) days after a Responsible
Officer becoming aware of any of the following, a written notice setting forth
the nature thereof and the action, if any, that the Company or an ERISA
Affiliate proposes to take with respect thereto:

                                    (i) with respect to any Plan, any reportable
                  event, as defined in Section 4043(b) of ERISA and the
                  regulations thereunder, for which notice

                                      -21-

<PAGE>



                  thereof has not been waived pursuant to such regulations as in
                  effect on the date hereof; or

                                    (ii) the taking by the PBGC of steps to
                  institute, or the threatening by the PBGC of the institution
                  of, proceedings under Section 4042 of ERISA for the
                  termination of, or the appointment of a trustee to administer,
                  any Plan, or the receipt by the Company or any ERISA Affiliate
                  of a notice from a Multiemployer Plan that such action has
                  been taken by the PBGC with respect to such Multiemployer

                  Plan; or

                                    (iii) any event, transaction or condition
                  that could result in the incurrence of any liability by the
                  Company or any ERISA Affiliate pursuant to Title I or IV of
                  ERISA or the penalty or excise tax provisions of the Code
                  relating to employee benefit plans, or in the imposition of
                  any Lien on any of the rights, properties or assets of the
                  Company or any ERISA Affiliate pursuant to Title I or IV of
                  ERISA or such penalty or excise tax provisions, if such
                  liability or Lien, taken together with any other such
                  liabilities or Liens then existing, would reasonably be
                  expected to have a Material Adverse Effect.

         11.      Redemption of Debentures; Repurchase Rights; Mandatory Sales.

                  11.1. Right of Redemption. Any redemption or repurchase of the
Debentures at the election of the Company or otherwise, as permitted or required
by any provision of the Debentures or this Agreement, shall be made in
accordance with such provision and this Section 11.

                  11.2. Company Right of Redemption. Subject to Section 11.5,
the Company may, at any time other than during a Change of Control Period,
redeem all or part of the Debentures, subject to satisfaction of the following
conditions:

                            (a) The Company shall give a notice of redemption to
         each holder in the manner provided in Section 23 not less than fifteen
         (15) nor, subject to Section 11.5(a), more than sixty (60) days prior
         to the applicable Redemption Date. Such notice shall disclose the
         proposed source of funds for the redemption (e.g. private placement,
         working capital, public offering).

                            (b) The amount to be redeemed must be (i) at least
         $5,000,000, in principal amount of Debentures and (ii) at least
         twenty-five percent (25%) of the then Outstanding Debentures (unless
         the principal amount of then Outstanding Debentures is less than
         $5,000,000, in which case the amount to be redeemed shall be such
         principal amount). In the event that less than all of the then
         Outstanding Debentures are to be redeemed, the Company shall redeem
         Debentures pro rata from each holder of Debentures based upon the
         respective principal amounts of the Debentures outstanding on the date
         of redemption.

                                      -22-

<PAGE>




                            (c) The Company shall pay the applicable Redemption
         Price to each holder of Debentures on the Redemption Date, in cash, in
         immediately available funds. With respect to each holder of Debentures,

         the Redemption Price shall be determined by multiplying (A) the sum of
         (i) the number of Conversion Shares such holder would receive on the
         Redemption Date with respect to the Debentures to be redeemed if such
         Debentures were to be converted in accordance with the provisions of
         Section 15 hereof and (ii) the number of Interest Shares representing
         the accrued but unpaid interest on the Debentures to be redeemed, as of
         the Redemption Date, by (B) the greater of (x) the average of the daily
         Closing Prices per share of Common Stock for the twenty (20) Trading
         Days immediately preceding the Redemption Date or (y) $17.50.

                  11.3. Redemption and Repurchase Rights upon Change of Control
                        Event.

                            (a) During any Change of Control Period either the
         Company (subject to Section 11.5) or any holder of Debentures may give
         notice to the other pursuant to which the Company shall be required to
         purchase all (but not less than all) of the Debentures (if the notice
         is given by the Company) or all of the Debentures held by a holder (if
         the notice is given by such holder) in accordance with the provisions
         of this Section 11.3. The Company shall give notice in accordance with
         Section 23 to each holder of Debentures, within five (5) Business Days
         of the commencement of a Change of Control Period.

                            (b) Notice of a redemption by the Company or the
         exercise of a repurchase right by any holder of Debentures pursuant to
         this Section 11.3 may be given (in the manner provided in Section 23)
         at any time during the Change of Control Period. The repurchase date
         (the "Repurchase Date") for any redemption or repurchase under this
         Section 11.3 shall be a Business Day specified in the notice that is
         not less than fifteen (15) nor, subject to Section 11.5(a), more than
         sixty (60) days from the date notice is given. Any notice given by the
         Company under this Section 11.3 shall disclose the proposed source of
         funds for the Company's redemption (e.g. private placement, working
         capital, public offering).

                            (c) The Company shall pay the applicable Repurchase
         Price to each holder of Debentures from whom Debentures are to be
         redeemed or repurchased on the Repurchase Date, in cash, in immediately
         available funds. With respect to each holder of Debentures from whom
         Debentures are to be redeemed or repurchased pursuant to this Section
         11.3, the repurchase price (the "Repurchase Price") shall be determined
         by multiplying (A) the sum of (i) the number of Conversion Shares such
         holder would receive on the Repurchase Date with respect to the
         Debentures to be repurchased if such Debentures were to be converted in
         accordance with the provisions of Section 15 hereof and (ii) the number
         of Interest Shares representing the accrued but unpaid interest on the
         Debentures to be repurchased as of the Repurchase Date by (B) the
         greatest of: (x) the average of the daily Closing Prices per share of
         Common Stock for the twenty (20) Trading Days immediately preceding the
         Repurchase Date, (y) $17.50, or (z) the price

                                      -23-

<PAGE>




         per share paid for the Common Stock (whether in assets, cash,
         securities or any combination thereof) in the Change of Control
         transaction to public holders of the Common Stock generally.

                  11.4. Mandatory Sale. Subject to Section 11.5, the Company may
require each holder of Debentures to sell (a "Mandatory Sale") all or subject to
paragraph (b) below, a part of the Conversion Shares and Interest Shares such
holder would be entitled to receive if such holder converted, as of the
Mandatory Sale Date, all of the Debentures owned by such holder on the date such
holder receives the notice specified in paragraph (a) below (the "Underlying
Shares") provided all of the following terms and conditions are met:

                            (a) The Company shall give a notice of the Mandatory
         Sale in the manner provided in Section 23 not less than fifteen (15)
         nor, subject to Section 11.5(a), more than sixty (60) days prior to the
         date specified in such notice (the "Mandatory Sale Date"). Such notice
         shall disclose the proposed source of funds for the Mandatory Sale
         (e.g. private placement, public offering).

                            (b) The Company may only exercise its right to
         require a Mandatory Sale on one occasion. If less than all of the
         Underlying Shares are to be subject to the Mandatory Sale, the
         aggregate sale price (the "Mandatory Sale Price") with respect to such
         Underlying Shares must be at least $10,000,000. In the event that the
         Mandatory Sale shall apply to less than all of the Underlying Shares,
         the Underlying Shares subject to the Mandatory Sale shall be allocated
         pro rata among the holders of the Debentures based upon the respective
         principal amounts of the Debentures of such holders outstanding on the
         date of the Mandatory Sale.

                            (c) The Mandatory Sale may be accomplished by an
         underwritten public offering of the Underlying Shares or by a private
         placement of the Underlying Shares, in either case arranged by a
         nationally recognized investment banking firm reasonably acceptable to
         the holders of a majority of the Underlying Shares subject to the
         Mandatory Sale.

                            (d) The Company will indemnify and hold each holder
         of Debentures harmless with respect to any liability arising out of any
         misstatement or omission in the registration statement or private
         placement memorandum and other documents prepared by or on behalf of
         the Company in connection with the Mandatory Sale transaction (other
         than information provided by such holder expressly for inclusion
         therein) and will pay all of the expenses of the Mandatory Sale,
         including any registration fees, any underwriting discount or placement
         agent fees, and the reasonable fees of one legal counsel selected by
         the holders of a majority of the Underlying Shares subject to the
         Mandatory Sale in connection with the review of such registration
         statement or private placement memorandum.



                                      -24-

<PAGE>



                            (e) The underwriters or the private placement
         purchasers shall pay each holder of Debentures in connection with the
         Mandatory Sale, the Mandatory Sale Price, in cash, in immediately
         available funds. The Mandatory Sale Price for each holder of Debentures
         shall be determined by multiplying the number of Underlying Shares of
         such holder subject to the Mandatory Sale by the greater of (x) an
         amount that is at least ninety-five percent (95%) of the average of the
         daily Closing Prices per share of Common Stock for the twenty (20)
         Trading Days immediately preceding the Mandatory Sale Date (plus such
         percentage in excess of ninety-five percent (95%) of such average if
         paid by the purchasers of the Underlying Shares) or (y) $17.50. In the
         event that the underwriters or private placement purchasers do not for
         any reason pay each holder of Debentures the full Mandatory Sale Price
         to which such holder is entitled, the Company shall pay such holder
         within one (1) Business Day of the Mandatory Sale Date the positive
         difference (up to the full amount of the Mandatory Sale Price) between
         the Mandatory Sales Price to which such holder was entitled and the
         aggregate amount such holder actually received from the underwriters or
         the private placement purchasers in connection with the Mandatory Sale.

                  11.5. Restriction on Conversion Rights; Withdrawal of Notice.

                  (a) Following receipt from the Company of any notice of
redemption pursuant to Section 11.2 or Section 11.3 or any notice of Mandatory
Sale pursuant to Section 11.4 (each, a "Company Notice"), each holder of
Debentures shall have ten (10) Business Days after receipt of the Company Notice
(the "Decision Period") in which to notify the Company in accordance with the
provisions of Section 23 that such holder wishes to convert all or a part of
such holder's Debentures (the "Converted Debenture Portion") into shares of
Common Stock in accordance with the provisions of Section 15.2. If such notice
is given in a timely manner by such holder (a "Holder Notice"), the proposed
redemption of Debentures by the Company or proposed Mandatory Sale of Underlying
Shares arranged by the Company pursuant to Section 11.2, 11.3 or 11.4 shall not
impair the right of such holder to convert the Converted Debenture Portion into
shares of Common Stock pursuant to Section 15.2. Except as provided in the
preceding sentence, no amount of Debentures of any holder specified in the
Company Notice as subject to redemption pursuant to Section 11.2 or Section 11.3
or Mandatory Sale pursuant to Section 11.4 may be converted into shares of
Common Stock pursuant to Section 15.2 during the period commencing on the date
of the Company Notice and ending on the earliest of (x) the date of any
withdrawal of the Company Notice pursuant to Section 11.5(b), (y) subject to
Section 11.5(c), the sixty-first (61st) day following the earlier of (i) the
expiration of the Decision Period or (ii) the date of the Company's receipt of
the Holder Notice of such holder (the "Company Notice Expiration Date") or (z)
the applicable Redemption, Repurchase or Mandatory Sale Date. Each holder giving
a Holder Notice shall convert the Converted Debenture Portion specified in the
Holder Notice within fifteen (15) Business Days after the applicable Redemption,
Repurchase, or Mandatory Sale Date. Notwithstanding any other provision of this

Agreement, the Company shall have given notice of redemption in compliance with
Section 11.2(a) and Section 11.3(b) and notice of a Mandatory Sale in compliance
with Section 11.4(a) if the Redemption Date, the Repurchase Date or the
Mandatory Sale Date, as

                                      -25-

<PAGE>



the case may be, occurs not later than the day immediately preceding the Company
Notice Expiration Date.

                  (b) The Company shall have the right to withdraw any Company
Notice by notifying the holders of the Debentures of such withdrawal in
accordance with the provisions of Section 23, but only if the notice of
withdrawal is accompanied by a copy of a written notice, to the effect set forth
in the following sentence from the underwriter, placement agent or proposed
private placement purchaser from whom the Company intended to raise the capital
necessary to complete the proposed redemption or with whom the Company intended
to place the Underlying Shares in a proposed Mandatory Sale. Such notice shall
state that the amount of Company securities included in the proposed offering
(which, in the case of a Mandatory Sale, shall be the Underlying Shares included
in such offering) would not be able to be sold at a price sufficient to yield
proceeds at least equal to the redemption price specified in Section 11.2 or
Section 11.3, as applicable, or the Mandatory Sale Price. If any Company Notice
is properly withdrawn pursuant to this Section 11.5(b), failure by the Company
to make any redemption payment pursuant to Section 11.2 or Section 11.3 or to
arrange for or make any payment in connection with a Mandatory Sale pursuant to
Section 11.4, in any case as proposed in such withdrawn Company Notice, (i)
shall not constitute an Event of Default under this Agreement and (ii) shall not
constitute the one-time exercise by the Company of its rights under Section
11.4(b).

                  (c) Notwithstanding any other provision of this Agreement,
following receipt of a Company Notice, if the HSR Act would require any filings
to be made with respect to the conversion of any Debenture subject to a Company
Notice, each holder of Debentures subject to the filing requirements of the HSR
Act upon any conversion of a Debenture subject to a Company Notice shall have
ten (10) Business Days after the expiration or early termination of any
applicable HSR Act waiting period to exercise the conversion privilege in
accordance with Section 15.2 with respect to such Debentures before any proposed
redemption of such Debentures by the Company or proposed Mandatory Sale of
Underlying Shares arranged by the Company pursuant to Section 11.2, 11.3 or 11.4
shall impair the right of such holder to convert such Debentures, and the
Company's right to redeem the Debentures of any such holder or to require the
Mandatory Sale of any Underlying Shares of any such holder shall be suspended
until ten (10) Business Days after the expiration or early termination of the
applicable HSR Act waiting period (an "HSR Suspension Period"). If any HSR Act
filing shall be required hereunder, the Company Notice Expiration Date shall be
the sixty-first (61st) day after the latest HSR Suspension Period applicable to
any Holder.


         12. Business Covenants. From the Closing Date, and thereafter so long
as any of the Debentures are outstanding, the Company will perform or comply
with, as required, each of the following covenants:

                  12.1. Payment of Debentures and Maintenance of Office. The
Company will punctually pay or cause to be paid the principal, premium, if any,
and interest to become due in respect of the Debentures according to the terms
thereof and hereof and will maintain an

                                      -26-

<PAGE>



office within the continental boundaries of the United States of America where
notices, presentations and demands in respect of this Agreement and the
Debentures may be made upon it and will notify each holder of a Debenture of any
change of location of such office. Such office shall first be maintained at 2440
Research Boulevard, Suite 400, Rockville, Maryland 20850.

                  12.2. Payment of Taxes and Claims. The Company will, and will
cause each of its Subsidiaries to, pay and discharge promptly (a) all taxes,
assessments and other governmental charges imposed upon it or any of its
properties or assets or in respect of any of its franchises, business, income or
profits before the same shall become delinquent and (b) all lawful claims of
materialmen, mechanics, carriers, warehousemen, landlords and other similar
Persons for labor, materials, supplies and rentals which, if unpaid, might by
law become a lien or charge upon its property, except to the extent that the
failure so to pay any amount pursuant to (a) or (b) would not have a Material
Adverse Effect; provided, however, that none of the foregoing need be paid while
being contested in good faith by appropriate proceedings initiated within the
period allowed by applicable law, rule or regulation and diligently conducted so
long as (i) adequate book reserves have been established in accordance with GAAP
with respect thereto and (ii) neither the Company's nor any such Subsidiary's
title to or right to the use of its properties is materially adversely affected
thereby.

                  12.3. Maintenance of Properties and Corporate Existence. The
Company and its Subsidiaries will each:

                            (a) maintain its property in good condition and make
         all needful and proper renewals, replacements, additions, betterments
         and improvements thereto, all as in the judgment of the Company may be
         necessary so that the business carried on in connection therewith may
         be conducted properly and advantageously at all times; provided that
         nothing in this Section 12.3 shall prevent the Company or any
         Subsidiary from discontinuing the use, operation or maintenance of any
         properties or disposing of any of them if such discontinuance or
         disposal is, in the judgment of the Company, desirable in the conduct
         of the business of the Company or such Subsidiary;

                            (b) subject to Section 13.12 (if and to the extent
         in effect), keep adequately insured, by financially sound and reputable

         insurers, all of its property of a character usually insured by
         entities engaged in the same or a similar business similarly situated
         against loss or damage of the kinds and in amounts customarily insured
         against by such entities and with deductibles or co-insurance no
         greater than is customary, and carry, with such insurers in customary
         amounts and with deductibles or co-insurance no greater than is
         customary, such other insurance, including public liability insurance
         and liability insurance against claims for any violation of applicable
         law, as is usually carried by entities engaged in the same or a similar
         business similarly situated, provided that compliance with the
         insurance covenants in the Senior Indentures will be satisfactory
         compliance with this paragraph;


                                      -27-

<PAGE>



                            (c) keep proper books of record and account in which
         full, true and correct entries will be made of all its business
         transactions in accordance with GAAP;

                            (d) set aside on its books from its earnings for
         each fiscal year, beginning with the first such year ending subsequent
         to the date hereof and for each fiscal year thereafter, in amounts
         deemed adequate in the opinion of the Company, all proper accruals and
         reserves which, in accordance with GAAP, should be set aside from such
         earnings in connection with its business, including, without
         limitation, reserves for depreciation, obsolescence and/or amortization
         and accruals for taxes for such period, including all taxes based on or
         measured by income or profits; and

                            (e) except as otherwise permitted or contemplated
         hereby, do or cause to be done all things necessary to preserve and
         keep in full force and effect its corporate existence and such rights,
         patents, trademarks, copyrights, licenses, permits, franchises and
         governmental authorizations as the Company determines to be necessary
         for the present and presently planned future conduct of its business.

                  12.4. Compliance with Law. Neither the Company nor any of its
Subsidiaries  will:

                            (a) violate any laws, ordinances, governmental rules
         or regulations to which it is, or might become, subject, unless the
         same are being contested by the Company or such Subsidiary in good
         faith and by appropriate proceedings which shall effectively prevent
         the imposition of any penalty on the Company or such Subsidiary for
         such noncompliance, or

                            (b) fail to use its best efforts to obtain any
         patents, trademarks, service marks, trade names, copyrights, design
         patents, licenses, permits, franchises or other governmental

         authorizations necessary to the ownership of its property or to the
         conduct of its business,

which violation or failure would or might have a Material Adverse Effect.

                  12.5.     [Reserved.]

                  12.6. When Company May Merge, Etc. The Company shall not
consolidate with or merge into, or transfer all or substantially all of its
assets to, another Person unless: (i) such Person is a corporation, partnership
or limited liability company organized under the laws of the United States, one
of the States thereof or the District of Columbia; (ii) the resulting, surviving
or transferee corporation, partnership or limited liability company assumes by
written agreement all the obligations of the Company under the Debentures and
this Agreement; (iii) immediately after giving effect to such transaction no
Event of Default or Potential Event of Default shall have occurred and be
continuing; and (iv) the Company shall have delivered to you an Officers'
Certificate and an opinion of counsel of the Company acceptable to you, each

                                      -28-

<PAGE>



stating that such consolidation, merger or transfer and such supplemental
agreement comply with this Agreement, and thereafter all obligations of the
predecessor shall terminate.

         Upon any consolidation or merger or any transfer of all or
substantially all of the assets of the Company in accordance with this Section
12.6, the successor corporation, partnership or limited liability company formed
by such consolidation or into which the Company is merged or to which such
transfer is made shall succeed to, and be substituted for, and may exercise
every right and power of, the Company under this Agreement, with the same effect
as if such successor had been named as the Company herein, all without any
further act or deed on the part of such successor being required.

         Section 12.6 shall cease to apply after the Senior Notes Reduction
Date.

                  12.7. Listing. The Company will list on each national
securities exchange on which any Common Stock may at any time be listed and on
the Nasdaq National Market, if the Common Stock is authorized for quotation
thereon, subject to official notice of issuance upon the conversion of the
Debentures or upon payment of interest, and will maintain such listing of, (i)
all Conversion Shares and (ii) all Interest Shares.

                  12.8. Issuances of Guarantees by New Restricted Subsidiaries.
On the date that any Person becomes a Restricted Subsidiary, the Company will
cause such additional Restricted Subsidiary to execute a supplemental Subsidiary
Guarantee, providing for a full and unconditional guarantee by such additional
Restricted Subsidiary of the Company's obligations under the Debentures and this
Agreement to the same extent as that set forth in the Subsidiary Guarantee;

provided that, in the case of any new Restricted Subsidiary that becomes a
Restricted Subsidiary through the acquisition of a majority of its voting
Capital Stock by the Company or any other Restricted Subsidiary, such
supplemental Subsidiary Guarantee may be subordinated to the extent required by
the obligations of such new Restricted Subsidiary existing on the date of such
acquisition that were not incurred in contemplation of such acquisition.

                  12.9. Subsidiaries. The Company will provide to you a complete
and accurate list of its Subsidiaries each time Exhibit D attached hereto
becomes inaccurate and cause each Subsidiary which guarantees any Indebtedness
to promptly execute and deliver a Subsidiary Guarantee to you.

                  12.10. Notice. The Company will give prompt written notice to
you of any Event of Default or Potential Event of Default hereunder.

                  12.11. Waiver of Stay, Extension or Usury Laws. The Company
covenants (to the extent that it may lawfully do so) that it will not at any
time insist upon, or plead, or in any manner whatsoever claim or take the
benefit or advantage of, any stay or extension law or any usury law or other law
that would prohibit or forgive the Company from paying all or any portion of the
principal of, premium, if any, or interest on the Debentures as contemplated
herein, whenever enacted, now or at any time hereafter in force, or that may
affect the

                                      -29-

<PAGE>



covenants or the performance of this Agreement; and (to the extent that it may
lawfully do so) the Company hereby expressly waives all benefit or advantage of
any such law and covenants that it will not hinder, delay or impede the
execution of any power herein granted to the holders of the Debentures, but will
suffer and permit the execution of every such power as though no such law had
been enacted.

         13. Financial Covenants. From the Senior Notes Reduction Date, and
thereafter so long as any of the Debentures are outstanding, the Company will
perform or comply with, as required, each of the following covenants:

                  13.1.     Merger and Sale of Assets.

                            (a) The Company will not consolidate with or merge
         with or into any other Person or permit any other Person (other than a
         Subsidiary as provided by paragraph (b) below) to consolidate with or
         merge into it, or sell, lease, transfer or otherwise dispose of all or
         substantially all of its assets (as an entirety or substantially an
         entirety in one transaction or a series of related transactions),
         unless:

                            (i)     the entity which survives such merger or
                                    results from such consolidation or the
                                    corporation to which such sale, lease,

                                    transfer or other disposition is made (the
                                    "surviving corporation") is a corporation
                                    organized under the laws of the United
                                    States of America or a jurisdiction thereof;

                            (ii)    the due and punctual payment of the
                                    principal of and premium, if any, and
                                    interest on all of the Debentures, according
                                    to their tenor, and of the covenants
                                    therein, and the due and punctual
                                    performance and observance of all the
                                    covenants in this Agreement to be performed
                                    or observed by the Company, are expressly
                                    assumed in writing by the surviving
                                    corporation;

                            (iii)   before and immediately after the
                                    consummation of the transaction, and after
                                    giving effect thereto, no Event of Default
                                    or Potential Event of Default exists or
                                    would exist;

                            (iv)    immediately after giving effect to such
                                    transaction on a pro forma basis, the
                                    Company or any Person becoming the successor
                                    obligor of the Debentures shall have a
                                    Consolidated Net Worth equal to or greater
                                    than the Consolidated Net Worth of the
                                    Company immediately prior to such
                                    transaction;

                            (v)     immediately after consummation of the
                                    transaction, and after giving effect
                                    thereto, the surviving corporation would be
                                    permitted to incur at least $1.00 of
                                    additional Indebtedness under the first

                                      -30-

<PAGE>



                                    paragraph of Section 13.5; provided that
                                    this clause (v) shall not apply to a
                                    consolidation or merger with or into a
                                    Wholly Owned Restricted Subsidiary with a
                                    positive net worth; provided that, in
                                    connection with any such merger or
                                    consolidation, no consideration (other than
                                    Common Stock in the surviving Person or the
                                    Company) shall be issued or distributed to
                                    the stockholders of the Company;


                            (vi)    the provisions of Sections 15.8 and 15.13
                                    shall have been in all respects complied
                                    with in connection with such transaction;
                                    and

                            (vii)   the Company delivers to each holder of
                                    Debentures an Officers' Certificate
                                    (attaching the arithmetic computations to
                                    demonstrate compliance with clauses (iv) and
                                    (v)), in each case stating that such
                                    consolidation, merger or transfer complies
                                    with this provision and that all conditions
                                    precedent provided for herein relating to
                                    such transaction have been complied with;
                                    provided, however, that clauses (iv) and (v)
                                    above do not apply if, in the good faith
                                    determination of the Board of Directors of
                                    the Company, whose determination shall be
                                    evidenced by a Board Resolution, the
                                    principal purpose of such transaction is to
                                    change the state of incorporation of the
                                    Company; and provided further that any such
                                    transaction shall not have as one of its
                                    purposes the evasion of the foregoing
                                    limitations.

                            (b) No Subsidiary of the Company will consolidate
         with or merge into any other Person or permit any other Person to
         consolidate with or merge into it, except that a Subsidiary may
         consolidate with or merge into (i) the Company if each of the
         provisions of paragraph (a) are satisfied or (ii) another Subsidiary.

                  13.2. Limitation on Transactions with Affiliates and
Shareholders. The Company will not, and will not permit any Restricted
Subsidiary to, directly or indirectly, enter into, renew or extend any
transaction (including, without limitation, the purchase, sale, lease or
exchange of property or assets, or the rendering of any service) with any holder
(or any Affiliate of such holder) of five percent (5%) or more of any class of
Capital Stock of the Company or with any Affiliate of the Company or any
Restricted Subsidiary, except upon fair and reasonable terms no less favorable
to the Company or such Restricted Subsidiary than could be obtained, at the time
of such transaction or, if such transaction is pursuant to a written agreement,
at the time of the execution of the agreement providing therefor, in a
comparable arm's-length transaction with a Person that is not such a holder or
an Affiliate.

         The foregoing limitation does not limit, and shall not apply to (i)
transactions (A) approved by a majority of the disinterested members of the
Board of Directors or (B) for which the Company or a Restricted Subsidiary
delivers to you a written opinion of a nationally

                                      -31-

<PAGE>




recognized investment banking firm stating that the transaction is fair to the
Company or such Restricted Subsidiary from a financial point of view, (ii) any
transaction solely between the Company and any of its Wholly Owned Restricted
Subsidiaries or solely between Wholly Owned Restricted Subsidiaries, (iii) the
payment of reasonable and customary regular fees to directors of the Company who
are not employees of the Company, (iv) any payments or other transactions
pursuant to any tax-sharing agreement between the Company and any other Person
with which the Company files a consolidated tax return or with which the Company
is part of a consolidated group for tax purposes, (v) any Restricted Payments
not prohibited by Section 13.6 or (vii) Kingston's and Matra's rights to
commissions and other payments under sales representation agreements; Matra's
rights to payments, including without limitation incentive payments, under the
Orion 1 Satellite Contract and Orion 2 Satellite Contract; and Kingston's rights
to payments for services under network monitoring contracts, in each case as in
effect on the Closing Date and with such extensions, amendments and renewals
that may be entered into on terms at least as favorable to the Company or its
Restricted Subsidiaries, as the case may be, as the terms of agreements in
effect on the Closing Date. Notwithstanding the foregoing, any transaction
covered by the first paragraph of this Section 13.2 and not covered by clauses
(ii) through (v) of this paragraph, the aggregate amount of which exceeds $5
million in value, must be approved or determined to be fair in the manner
provided for in clause (i)(A) or (B) above.

                  13.3. Tax Consolidation. The Company will not, except as may
be required by any mandatory provision of applicable law, file or consent to the
filing of any consolidated income tax return with any Person other than a
Subsidiary.

                  13.4. Compliance with ERISA. The Company will not, and will
not permit any ERISA Affiliate to:

                            (a) engage in any transaction in connection with
         which the Company or any Subsidiary could be subject to either a
         material civil penalty assessed pursuant to Section 502(i) of ERISA or
         a material tax imposed by Section 4975 of the Code;

                            (b) terminate any Plan in a manner, or take any
         other action, which could result in any material liability of the
         Company or any ERISA Affiliate to the PBGC; or

                            (c) fail to make full payment when due of all
         amounts (including any amounts because of an accumulated funding
         deficiency) which, under the provisions of any Plan, the Code or ERISA,
         the Company or any ERISA Affiliate is required to pay as contributions
         to such Plan or otherwise.

As used in this Section 13.4, the term "accumulated funding deficiency" has the
meaning specified in Section 302 of ERISA and Section 412 of the Code.


                                      -32-


<PAGE>



                  13.5.     Limitation on Indebtedness.

                            (a) The Company will not, and will not permit any of
its Restricted Subsidiaries to, Incur any Indebtedness (other than the Senior
Notes, the Debentures and Indebtedness existing on the Senior Notes Reduction
Date); provided that the Company may Incur Indebtedness if, after giving effect
to the Incurrence of such Indebtedness and the receipt and application of the
proceeds therefrom, the Consolidated Leverage Ratio would be greater than zero
and less than 6 to 1.

                            Notwithstanding the foregoing, the Company and any
Restricted Subsidiary (except as specified below) may Incur each and all of the
following: (i) Indebtedness outstanding at any time that is (A) Incurred to
finance the purchase, construction, launch, insurance for and other costs with
respect to Orion 2 and Orion 3 or (B) in an aggregate principal amount not to
exceed (1) until Orion 2 or Orion 3 has been successfully delivered in orbit,
$50 million, (2) after the first of Orion 2 or Orion 3 has been successfully
delivered in orbit, $100 million and (3) after the second of Orion 2 or Orion 3
has been successfully delivered in orbit, $150 million, in each case under this
clause (i)(B); (ii) Indebtedness owed (A) to the Company or (B) to any of its
Restricted Subsidiaries; provided that any event which results in any such
Restricted Subsidiary ceasing to be a Restricted Subsidiary or any subsequent
transfer of such Indebtedness (other than to the Company or another Restricted
Subsidiary) shall be deemed, in each case, to constitute an Incurrence of such
Indebtedness not permitted by this clause (ii); (iii) Indebtedness issued in
exchange for, or the net proceeds of which are used to refinance or refund, then
outstanding Indebtedness, other than Indebtedness Incurred under clause (i)(B),
(ii), (iv), (vi) or (viii) of this paragraph, and any refinancings thereof in an
amount not to exceed the amount so refinanced or refunded (plus premiums,
accrued interest, fees and expenses); provided that Indebtedness the proceeds of
which are used to refinance the Debentures, the Subsidiary Guarantee or
Indebtedness that is pari passu with, or subordinated in right of payment to,
the Debentures shall only be permitted under this clause (iii) if (A) in case
the Debentures or the Subsidiary Guarantee are refinanced in part or the
Indebtedness to be refinanced is pari passu with the Debentures or the
Subsidiary Guarantee, such new Indebtedness, by its terms or by the terms of any
agreement or instrument pursuant to which such new Indebtedness is outstanding,
is expressly made pari passu with, or subordinate in right of payment to, the
remaining Debentures or the Subsidiary Guarantee, as the case may be, (B) in
case the Indebtedness to be refinanced is subordinated in right of payment to
the Debentures or the Subsidiary Guarantee, such new Indebtedness, by its terms
or by the terms of any agreement or instrument pursuant to which such new
Indebtedness is issued or remains outstanding, is expressly made subordinate in
right of payment to the Debentures or the Subsidiary Guarantee at least to the
extent that the Indebtedness to be refinanced is subordinated to the Debentures
or the Subsidiary Guarantee, as the case may be, and (C) such new Indebtedness,
determined as of the date of Incurrence of such new Indebtedness, does not
mature prior to the Stated Maturity of the Indebtedness to be refinanced or
refunded, and the Average Life of such new Indebtedness is at least equal to the

remaining Average Life of the Indebtedness to be refinanced or refunded; (iv)
Indebtedness (A) in respect of performance, surety or appeal bonds provided in
the ordinary course of business, (B) under Currency

                                      -33-

<PAGE>



Agreements and Interest Rate Agreements; provided that such agreements (a) are
designed solely to protect the Company or its Subsidiaries against fluctuations
in foreign currency exchange rates or interest rates and (b) do not increase the
Indebtedness of the obligor outstanding at any time other than as a result of
fluctuations in foreign currency exchange rates or interest rates or by reason
of fees, indemnities and compensation payable thereunder and (C) arising from
agreements providing for indemnification, adjustment of purchase price or
similar obligations, or from Guarantees or letters of credit, surety bonds or
performance bonds securing any obligations of the Company or any of its
Restricted Subsidiaries pursuant to such agreements, in any case Incurred in
connection with the disposition of any business, assets or Restricted Subsidiary
of the Company (other than Guarantees of Indebtedness Incurred by any Person
acquiring all or any portion of such business, assets or Restricted Subsidiary
of the Company for the purpose of financing such acquisition), in a principal
amount not to exceed the gross proceeds actually received by the Company or any
Restricted Subsidiary in connection with such disposition; (v) Indebtedness of
the Company, to the extent the net proceeds thereof are promptly (A) used to
purchase the Senior Notes in accordance with the redemption, repurchase and/or
change of control provisions of the Senior Note Indentures or (B) deposited to
defease the Senior Notes in accordance with the Senior Note Indentures; (vi)
Guarantees of the Senior Notes and Guarantees of Indebtedness of the Company by
any Restricted Subsidiary; (vii) Indebtedness Incurred to finance the cost
(including the cost of design, development, construction, installation,
improvement, transportation or integration) of equipment (other than Orion 2 and
Orion 3) or inventory acquired by the Company or a Wholly Owned Restricted
Subsidiary after the Closing Date; (viii) Indebtedness of the Company not to
exceed, at any one time outstanding, two (2) times the Net Cash Proceeds
received by the Company after the Closing Date from the issuance and sale of its
Capital Stock (other than Disqualified Stock) to a Person that is not a
Subsidiary of the Company (less the amount of such proceeds applied as provided
in clause (C)(2) of the first paragraph or clause (iii) or (iv) of the second
paragraph of Section 13.6), provided that such Indebtedness does not mature
prior to the Stated Maturity of the Debentures and has an Average Life longer
than the Debentures; and (ix) Redemption Indebtedness.

                            (b) For purposes of determining any particular
amount of Indebtedness under this Section 13.5, (1) Guarantees, Liens or
obligations with respect to letters of credit supporting Indebtedness otherwise
included in the determination of such particular amount shall not be included
and (2) any Liens granted pursuant to the equal and ratable provisions referred
to in Section 13.9 shall not be treated as Indebtedness. For purposes of
determining compliance with this Section 13.5, in the event that an item of
Indebtedness meets the criteria of more than one (1) of the types of
Indebtedness described in the above clauses, the Company, in its sole

discretion, shall classify such item of Indebtedness and only be required to
include the amount and type of such Indebtedness in one of such clauses.

                            (c) In the event that the Company or any Restricted
Subsidiary shall repay any Indebtedness (other than the Senior Notes) pursuant
to clause (i)(A) of Section 13.11 of this Agreement, the aggregate amount of
Indebtedness which may otherwise be Incurred under clauses (i)(B) and (ix) of
the second paragraph of paragraph (a) of this Section 13.5 shall be

                                      -34-

<PAGE>



reduced by the amount of such repayment. The Company shall designate how much of
such reduction shall be applied to each such clause.

                            (d) Notwithstanding any other provision of this
Section 13.5, (i) the maximum amount of Indebtedness that the Company or any
Restricted Subsidiary may Incur pursuant to this Section 13.5 shall not be
deemed to be exceeded due solely to fluctuations in the exchange rates of
currencies and (ii) the Company and each Guarantor may not Incur any
Indebtedness other than Acquired Indebtedness that is expressly subordinated to
any other Indebtedness of the Company or such Guarantor, as the case may be,
unless such Indebtedness, by its terms or the terms of any agreement or
instrument pursuant to which such Indebtedness is outstanding, is also expressly
made subordinate to the Debentures or the Subsidiary Guarantee, as the case may
be, at least to the extent that such Indebtedness is subordinated to such other
Indebtedness; provided that the limitation in this clause (ii) shall not apply
to distinctions between categories of Senior Indebtedness which exist by reason
of (a) any liens or other encumbrances arising or created in respect of some but
not all Senior Indebtedness, (b) intercreditor agreements between holders of
different classes of Senior Indebtedness or (c) different maturities or
prepayment provisions.

                  13.6. Limitation on Restricted Payments. The Company will not,
and will not permit any Restricted Subsidiary, directly or indirectly, to (i)
declare or pay any dividend or make any distribution on or with respect to its
Capital Stock (other than (x) dividends or distributions payable solely in
shares of its Capital Stock (other than Disqualified Stock) or in options,
warrants or other rights to acquire shares of such Capital Stock and (y) pro
rata dividends or distributions on Common Stock of Restricted Subsidiaries held
by minority stockholders, provided that such dividends do not in the aggregate
exceed the minority stockholders' pro rata share of such Restricted
Subsidiaries' net income from the first day of the fiscal quarter beginning
immediately following the Closing Date) held by Persons other than the Company
or any of its Restricted Subsidiaries, (ii) purchase, redeem, retire or
otherwise acquire for value any shares of Capital Stock of the Company, any
Guarantor or an Unrestricted Subsidiary (including options, warrants or other
rights to acquire such shares of Capital Stock) held by Persons other than the
Company and its Wholly Owned Subsidiaries, (iii) make any voluntary or optional
principal payment, or voluntary or optional redemption, repurchase, defeasance,
or other acquisition or retirement for value, of Indebtedness of the Company

that is subordinated in right of payment to the Debentures or of any Guarantor
that is subordinated to the Subsidiary Guarantee (other than, in each case, the
purchase, repurchase or the acquisition of Indebtedness in anticipation of
satisfying a sinking fund obligation, principal installment or final maturity,
in any case due within one (1) year of the date of acquisition) or (iv) make any
Investment, other than a Permitted Investment, in any Person (such payments or
any other actions described in clauses (i) through (iv) being collectively
"Restricted Payments") if, at the time of, and after giving effect to, the
proposed Restricted Payment: (A) a Potential Event of Default or Event of
Default shall have occurred and be continuing, (B) except with respect to
Investments and dividends on the Common Stock of any Guarantor, the Company
could not Incur at least $1.00 of Indebtedness under the first paragraph of
Section 13.5 or (C) the aggregate amount of all Restricted Payments (the amount,
if other than in cash, to be determined

                                      -35-

<PAGE>



in good faith by the Board of Directors, whose determination shall be conclusive
and evidenced by a Board Resolution) made after the Closing Date shall exceed
the sum of (1) fifty percent (50%) of the aggregate amount of the Adjusted
Consolidated Net Income (or if the Adjusted Consolidated Net Income is a loss,
minus 100% of the amount of such loss) (determined by excluding income resulting
from transfers of assets by the Company or a Restricted Subsidiary to an
Unrestricted Subsidiary) accrued on a cumulative basis during the period (taken
as one (1) accounting period) beginning on the first day of the fiscal quarter
immediately following the Closing Date and ending on the last day of the last
fiscal quarter preceding the Transaction Date for which reports have been filed
with the Commission plus (2) the aggregate Net Cash Proceeds received by the
Company or any Guarantor after the Closing Date from the issuance and sale
permitted by this Agreement of its Capital Stock (other than Disqualified Stock)
to a Person who is not a Subsidiary of the Company or any Guarantor or from the
issuance to a Person who is not a Subsidiary of the Company or any Guarantor of
any options, warrants or other rights to acquire Capital Stock of the Company
(in each case, exclusive of any Disqualified Stock or any options, warrants or
other rights that are redeemable at the option of the holder, or are required to
be redeemed, prior to the Stated Maturity of the Debentures), in each case
except to the extent such Net Cash Proceeds are used to Incur Indebtedness
pursuant to clause (viii) of the second paragraph of Section 13.5, plus (3) an
amount equal to the net reduction in Investments (other than reductions in
Permitted Investments) in any Person resulting from payments of interest on
Indebtedness, dividends, repayments of loans or advances, or other transfers of
assets, in each case to the Company or any Restricted Subsidiary or from the Net
Cash Proceeds from the sale of any such Investment (except, in each case, to the
extent any such payment or proceeds are included in the calculation of Adjusted
Consolidated Net Income), or from redesignations of Unrestricted Subsidiaries as
Restricted Subsidiaries (valued in each case as provided in the definition of
"Investments"), not to exceed, in each case, the amount of Investments
previously made by the Company or any Restricted Subsidiary in such Person or
Unrestricted Subsidiary.


                  The foregoing provision shall not be violated by reason of:
(i) the payment of any dividend within sixty (60) days after the date of
declaration thereof if, at said date of declaration, such payment would comply
with the foregoing paragraph; (ii) the redemption, repurchase, defeasance or
other acquisition or retirement for value of Indebtedness that is subordinated
in right of payment to the Debentures including premium, if any, and accrued and
unpaid interest, with the proceeds of, or in exchange for, Indebtedness Incurred
under clause (iii) of the second paragraph of part (a) of Section 13.5; (iii)
the repurchase, redemption or other acquisition of Capital Stock of the Company
(or options, warrants or other rights to acquire such Capital Stock) in exchange
for, or out of the proceeds of a substantially concurrent offering of, shares of
Capital Stock (other than Disqualified Stock) of the Company; (iv) the making of
any principal payment or the repurchase, redemption, retirement, defeasance or
other acquisition for value of Indebtedness of the Company which is subordinated
in right of payment to the Debentures in exchange for, or out of the proceeds
of, a substantially concurrent offering of, shares of the Capital Stock of the
Company (other than Disqualified Stock); (v) payments or distributions, to
dissenting stockholders pursuant to applicable law, pursuant to or in connection
with a consolidation, merger or transfer of assets that complies with the
provisions of this Agreement applicable to mergers, consolidations and transfers
of all or substantially all of the

                                      -36-

<PAGE>



property and assets of the Company; (vi) the repurchase, redemption or other
acquisition of (A) shares of Series A Preferred Stock or Series B Preferred
Stock which were outstanding on the Closing Date and (B) shares of Preferred
Stock pursuant to options that were outstanding on the Closing Date, in exchange
for, or out of the proceeds of, an issuance of Indebtedness Incurred under
clause (iii) of the second paragraph of part (a) of Section 13.5; (vii)
Investments, to the extent the amount invested consists solely of Net Cash
Proceeds received by the Company or any Guarantor within six months of the
making of such Investment, from the issuance and sale permitted by this
Agreement of its Capital Stock (other than Disqualified Stock) to a Person who
is not a Subsidiary of the Company or any Guarantor; (viii) Investments, the sum
of which does not exceed $5 million at any one time outstanding; (ix) cash
payments, not to exceed $3 million, in lieu of the issuance of fractional shares
of Capital Stock of the Company upon the exercise of any warrants to buy, or
upon the conversion of any securities convertible into, Capital Stock of the
Company or (x) the purchase, redemption, retirement or other acquisition for
value of the warrants issued to the holders of the Senior Notes in connection
with their acquisition of the Senior Notes pursuant to a repurchase offer
provided for in the warrant agreement, dated as of January 31, 1997, between the
Company and Bankers Trust Company as warrant agent; provided that, except in the
case of clauses (i) and (iii), no Potential Event of Default or Event of Default
shall have occurred and be continuing or occur as a consequence of the actions
or payments set forth therein.

                  Each Restricted Payment permitted pursuant to the preceding
paragraph (other than the Restricted Payment referred to in clause (ii) thereof

and an exchange of Capital Stock for Capital Stock or Indebtedness referred to
in clause (iii) or (iv) thereof) and the Net Cash Proceeds from any issuance of
Capital Stock referred to in clauses (iii) and (iv) shall be included in
calculating whether the conditions of clause (C) of the first paragraph of this
Section 13.6 have been met with respect to any subsequent Restricted Payments.
In the event the proceeds of an issuance of Capital Stock of the Company are
used for the redemption, repurchase or other acquisition of the Debentures, or
Indebtedness that is pari passu with the Debentures, then the Net Cash Proceeds
of such issuance shall be included in clause (C) of the first paragraph of this
Section 13.6 only to the extent such proceeds are not, within six months, used
for such redemption, repurchase or other acquisition of Indebtedness.

                  Any Restricted Payments made other than in cash shall be
valued at fair market value. The amount of any Investment "outstanding" at any
time shall be deemed to be equal to the amount of such Investment on the date
made, less the return of capital to the Company and its Restricted Subsidiaries
with respect to such Investment (up to the amount of such Investment on the date
made).

                  13.7. Limitation on the Issuance and Sale of Capital Stock of
Restricted Subsidiaries. The Company will not sell, and will not permit any
Restricted Subsidiary, directly or indirectly, to issue or sell, any shares of
Capital Stock of a Restricted Subsidiary (including options, warrants or other
rights to purchase shares of such Capital Stock) except (i) to the Company or a
Wholly Owned Restricted Subsidiary; (ii) issuances of director's qualifying
shares or sales to foreign nationals of shares of Capital Stock of foreign
Restricted Subsidiaries, to the

                                      -37-

<PAGE>



extent required by applicable law; (iii) if, immediately after giving effect to
such issuance or sale, such Restricted Subsidiary would no longer constitute a
Restricted Subsidiary, provided any Investment in such Person remaining after
giving effect to such issuance or sale would have been permitted to be made
under Section 13.6, if made on the date of such issuance or sale; and (iv)
issuances or sales of Common Stock of any Restricted Subsidiary, the Net Cash
Proceeds of which are promptly applied pursuant to clause (i)(A) or (i)(B) of
the second paragraph of Section 13.11 of this Agreement; provided that at no
time may a Restricted Subsidiary, the Common Stock of which has been issued or
sold pursuant to this clause (iv), be the owner of a satellite.

                  13.8. Issuances of Guarantees by New Restricted Subsidiaries.
On the date that any Person becomes a Restricted Subsidiary the Company will
cause such additional Restricted Subsidiary to execute a supplemental Subsidiary
Guarantee, providing for a full and unconditional guarantee by such additional
Restricted Subsidiary of the Company's obligations under the Debentures and this
Agreement to the same extent as that set forth in the Subsidiary Guarantee;
provided that, in the case of any new Restricted Subsidiary that becomes a
Restricted Subsidiary through the acquisition of a majority of its voting
Capital Stock by the Company or any other Restricted Subsidiary, such

supplemental Subsidiary Guarantee may be subordinated to the extent required by
the obligations of such new Restricted Subsidiary existing on the date of such
acquisition that were not incurred in contemplation of such acquisition.

                  13.9. Limitation on Liens. The Company will not, and will not
permit any Restricted Subsidiary to, create, incur, assume or suffer to exist
any Lien of any kind securing Indebtedness that is pari passu with, or
subordinated in right of payment to, the Debentures on any of its assets or
properties of any character, or any shares of Capital Stock or Indebtedness of
any Restricted Subsidiary, without making effective provision for all of the
Debentures and all other amounts due under this Agreement to be directly secured
equally and ratably with (or, if the obligation or liability to be secured by
such Lien is subordinated in right of payment to the Debentures, prior to) the
obligation or liability secured by such Lien.

                  The foregoing limitation does not apply to (i) Liens existing
on the Closing Date; (ii) Liens granted after the Closing Date on any assets or
Capital Stock of the Company or its Restricted Subsidiaries created in favor of
the holders of Debentures; (iii) Liens with respect to the assets of a
Restricted Subsidiary granted by such Restricted Subsidiary to the Company or a
Wholly Owned Restricted Subsidiary to secure Indebtedness owing to the Company
or such other Restricted Subsidiary; (iv) Liens securing Indebtedness which is
Incurred to refinance secured Indebtedness which is permitted to be Incurred
under clause (iii) of the second paragraph of Section 13.5; provided that such
Liens do not extend to or cover any property or assets of the Company or any
Restricted Subsidiary other than the property or assets securing the
Indebtedness being refinanced; or (v) Permitted Liens.

                  The Company will not, and will not permit any Restricted
Subsidiary to, create, incur, assume or suffer to exist any Lien on Orion 1,
Orion 2 or Orion 3 that secures Indebtedness other than pursuant to clause (xxi)
of the definition of Permitted Lien.


                                      -38-

<PAGE>



                  13.10. Limitation on Sale-Leaseback Transactions. The Company
will not, and will not permit any Restricted Subsidiary to, directly or
indirectly, enter into any sale-leaseback transaction involving any of its
assets or properties, whether now owned or hereafter acquired, whereby the
Company or a Restricted Subsidiary sells or transfers such assets or properties
and then or thereafter leases such assets or properties or any part thereof or
any other assets or properties which the Company or such Restricted Subsidiary,
as the case may be, intends to use for substantially the same purpose or
purposes as the assets or properties sold or transferred.

                  The foregoing restriction does not apply to any sale-leaseback
transaction if (i) the lease is for a period, including renewal rights, of not
in excess of three (3) years; (ii) the lease secures or relates to industrial
revenue or pollution control bonds; (iii) the transaction is solely between the

Company and any Wholly Owned Restricted Subsidiary or solely between Wholly
Owned Restricted Subsidiaries; or (iv) the Company or such Restricted
Subsidiary, within twelve (12) months after the sale or transfer of any assets
or properties is completed, applies an amount not less than the net proceeds
received from such sale or transfer in accordance with clause (i) (A) or (i) (B)
of the second paragraph of Section 13.11.

                  13.11. Limitation on Asset Sales. The Company will not, and
will not permit any Restricted Subsidiary to, consummate any Asset Sale unless
(i) the consideration received by the Company or such Restricted Subsidiary
(including the amount of any Released Indebtedness) is at least equal to the
fair market value of the assets sold or disposed of and (ii) at least
eighty-five percent (85%) of the consideration received (excluding the amount of
any Released Indebtedness) consists of cash or Temporary Cash Investments.

                  In the event and to the extent that the Net Cash Proceeds
received by the Company or any of its Restricted Subsidiaries from one or more
Asset Sales occurring on or after the Senior Notes Reduction Date in any period
of twelve (12) consecutive months exceed ten percent (10%) of Adjusted
Consolidated Net Tangible Assets (determined as of the date closest to the
commencement of such twelve (12) month period for which a consolidated balance
sheet of the Company and its Subsidiaries has been filed with the Commission),
then the Company shall or shall cause the relevant Restricted Subsidiary to (i)
within twelve months after the date Net Cash Proceeds so received exceed ten
percent (10%) of Adjusted Consolidated Net Tangible Assets (A) apply an amount
equal to such excess Net Cash Proceeds to permanently repay Senior Indebtedness
of the Company or of any Restricted Subsidiary owing to a Person other than the
Company or any of its Restricted Subsidiaries or (B) invest an equal amount, or
the amount not so applied pursuant to clause (A) (or enter into a definitive
agreement committing to so invest within twelve (12) months after the date of
such agreement), in property or assets (other than current assets) of a nature
or type or that are used in a business (or in a company having property and
assets of a nature or type, or engaged in a business) similar or related to the
nature or type of the property and assets of, or the business of, the Company
and its Restricted Subsidiaries existing on the date of such investment.

                  13.12. Insurance. The Company shall maintain (a) in-orbit
insurance with respect to Orion 1 in an amount at least equal to the cost to
replace such satellite with a satellite

                                      -39-

<PAGE>



of comparable or superior technological capability (as estimated by the Board of
Directors) and having at least as much transmission capacity as such satellite
was designed to have, and (b) with respect to Orion 2, Orion 3, each other
satellite to be launched by the Company or any Restricted Subsidiary and each
replacement satellite therefor, (i) launch insurance with respect to each such
satellite covering the period from the launch of such satellite to one hundred
eighty (180) days following such launch in an amount equal to or greater than
the sum of (A) the cost to replace such satellite pursuant to the contract

pursuant to which a replacement satellite will be constructed, (B) the cost to
launch a replacement satellite pursuant to the contract pursuant to which a
replacement satellite will be launched and (C) the cost of launch insurance for
such satellite or, in the event that the Company has reason to believe that the
cost of obtaining comparable insurance for a replacement satellite would be
materially higher, the Company's best estimate of the cost of such comparable
insurance and (ii) at all times subsequent to one hundred eighty (180) days
after the launch (if it is a Successful Launch) of each such satellite, in-orbit
insurance in an amount at least equal to the cost to replace such satellite with
a satellite of comparable or superior technological capability (as estimated by
the Board of Directors) and having at least as much transmission capacity as
such satellite was designed to have. The in- orbit insurance required by this
paragraph shall provide that if fifty percent (50%) or more of a satellite's
initial capacity is lost, the full amount of insurance will become due and
payable, and that if a satellite is able to maintain more than fifty percent
(50%) but less than ninety percent (90%) of its initial capacity, a pro rata
portion of such insurance will become due and payable. The insurance required by
this paragraph shall name the Company and/or any Guarantor as the sole loss
payee or payees, as the case may be, thereof.

         In the event that the Company (or a Guarantor) receives proceeds from
insurance relating to any satellite, the Company (or a Guarantor) may use a
portion of such proceeds to repay any vendor or third-party purchase money
financing pertaining to such satellite (other than Orion 1) that is required to
be repaid by reason of the loss giving rise to such insurance proceeds. The
Company (or a Guarantor) may use the remainder of such proceeds to develop,
construct, launch and insure a replacement satellite (including components for a
related ground spare) if (i) such replacement satellite is of comparable or
superior technological capability as compared with the satellite being replaced
and has at least as much transmission capacity as the satellite being replaced
and (ii) the Company will have sufficient funds to service the Company's
projected debt service requirements until the scheduled launch of such
replacement satellite and for one (1) year thereafter and to develop, construct,
launch and insure (in the amounts required by the preceding paragraph) such
replacement satellite, provided that such replacement satellite is scheduled to
be launched within fifteen (15) months of the receipt of such proceeds. Any such
proceeds not used as permitted by this paragraph shall be applied, within ninety
(90) days, to reduce Indebtedness of the Company.

         The Company shall further provide or cause to be provided, for itself
and its Restricted Subsidiaries, insurance (including appropriate
self-insurance) against loss or damage of the kinds considered reasonable by the
Company in the conduct of its business.


                                      -40-

<PAGE>



         The Company shall cause all properties owned by the Company or any
Subsidiary or used or held for use in the conduct of its business or the
business of any Subsidiary to be maintained and kept in good condition, repair

and working order and supplied with all necessary equipment and will cause to be
made all necessary repairs, renewals, replacements, betterments and improvements
thereof, all as in the judgment of the Company may be necessary so that the
business carried on in connection therewith may be properly and advantageously
conducted at all times; provided, however, that nothing in this Section 13.12
shall prevent the Company from discontinuing the maintenance of any of such
properties if such discontinuance is not disadvantageous in any material respect
to the holders of Debentures.

         Section 12.3(b) shall cease to apply after the Senior Notes Reduction
Date.

         14.      Subordination of Debentures.

                  14.1. Debentures Subordinated to Senior Indebtedness. The
Company covenants and agrees, and each holder of a Debenture, whether upon
original issue or upon transfer, assignment or exchange thereof by his
acceptance thereof, likewise covenants and agrees, that, to the extent and in
the manner hereinafter set forth in this Section 14, the payment of the
principal of and interest (except interest paid in the form of Junior
Securities) on each and all of the Debentures are hereby expressly made
subordinate and subject in right of payment to the prior payment in full in cash
or cash equivalents of all Senior Indebtedness.

                  14.2. Liquidation; Dissolution; Bankruptcy. In the event of
(a) any insolvency or bankruptcy case or proceeding, or any receivership,
liquidation, reorganization or other similar case or proceeding in connection
therewith, relative to the Company or to its creditors, as such, or to its
assets, (b) any liquidation, dissolution or other winding up of the Company,
whether voluntary or involuntary and whether or not involving insolvency or
bankruptcy, or (c) any assignment for the benefit of creditors or any other
marshalling of assets and liabilities of the Company, then and in any such event
specified in (a), (b) or (c) above (each such event, if any, herein sometimes
referred to as a "Proceeding") the holders of Senior Indebtedness shall be
entitled to receive payment in full in cash or cash equivalents of all amounts
due or to become due on or in respect of all Senior Indebtedness, or provision
shall be made for such payment in cash or cash equivalents or otherwise in a
manner satisfactory to the holders of Senior Indebtedness, before the holders of
the Debentures are entitled to receive any payment or distribution of any kind
or character, whether in cash, property or securities (other than Junior
Securities paid as interest on the Debentures), on account of principal of or
interest on the Debentures or on account of any purchase or other acquisition of
Debentures by the Company or any Subsidiary of the Company (all such payments,
distributions, purchases and acquisitions herein referred to, individually and
collectively, as a "Debenture Payment"), and to that end the holders of all
Senior Indebtedness shall be entitled to receive, for application to the payment
thereof, any Debenture Payment which may be payable or deliverable in respect of
the Debentures in any such Proceeding.


                                      -41-

<PAGE>




                            To the extent any payment of Senior Indebtedness
(whether by or on behalf of the Company, as proceeds of security or enforcement
of any right of setoff or otherwise) is declared to be fraudulent or
preferential, set aside or required to be paid to any receiver, trustee in
bankruptcy, liquidating trustee, agent or other similar Person under any
bankruptcy, insolvency, receivership, fraudulent conveyance or similar law, then
if such payment is recovered by, or paid over to, such receiver, trustee in
bankruptcy, liquidating trustee, agent or other similar Person, the Senior
Indebtedness or part thereof originally intended to be satisfied shall be deemed
to be reinstated and outstanding as if such payment had not occurred.

                            In the event that, notwithstanding the foregoing
provisions of this Section, the holder of any Debenture shall have received any
Debenture Payment before all Senior Indebtedness is paid in full or payment
thereof provided for in cash or cash equivalents or otherwise in a manner
satisfactory to the holders of Senior Indebtedness, then and in such event such
Debenture Payment shall be received and held in trust for the benefit of, and
shall be paid over or delivered forthwith to the trustee in bankruptcy,
receiver, liquidating trustee, custodian, assignee, agent or other Person making
payment or distribution of assets of the Company for application to the payment
of all Senior Indebtedness remaining unpaid, to the extent necessary to pay all
Senior Indebtedness in full, after giving effect to any concurrent payment or
distribution to or for the holders of Senior Indebtedness.

                            For purposes of this Section 14 only, the words "any
payment or distribution of any kind or character, whether in cash, property or
securities" shall not be deemed to include (a) any payment of interest on the
Debentures made solely in Junior Securities or (b) a payment or distribution of
stock or securities of the Company provided for by a plan of reorganization or
readjustment authorized by an order or decree of a court of competent
jurisdiction in a reorganization proceeding under any applicable bankruptcy law
or of any other corporation provided for by such plan of reorganization or
readjustment which stock or securities are subordinated in right of payment to
all then outstanding Senior Indebtedness at least to the same extent as the
Debentures are so subordinated as provided in this Section 14; provided that (1)
if a new corporation results from such reorganization or readjustment, such
corporation assumes the Senior Indebtedness and (2) the rights of the holders of
the Senior Indebtedness are not, without the consent of such holders, altered by
such reorganization or readjustment. The consolidation of the Company with, or
the merger of the Company into, another Person or the liquidation or dissolution
or the Company following the conveyance, transfer, sale or lease of all or
substantially all of its properties and assets to another Person upon the terms
and conditions set forth in either Section 12.6 or Section 13.1, as then
applicable, shall not be deemed a Proceeding for the purposes of this Section if
the Person formed by such consolidation or into which the Company is merged or
the Person which acquires by conveyance, transfer, sale or lease such properties
and assets, as the case may be, shall, as a part of such consolidation, merger,
conveyance, transfer, sale or lease comply with the conditions set forth in
either Section 12.6 or Section 13.1, as then applicable.

                  14.3. Default on Senior Indebtedness. In the event that any
Senior Payment Default (as defined below) shall have occurred and be continuing,

then no Debenture Payment

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<PAGE>



shall be made directly or indirectly unless and until such Senior Payment
Default shall have been cured or waived, such default or the benefits of this
sentence shall have been waived or shall have ceased to exist, or all amounts
then due and payable in respect of Senior Indebtedness to which such Senior
Payment Default relates shall have been paid in full, or provision shall have
been made for such payment in cash or cash equivalents or otherwise in a manner
satisfactory to the holders of Senior Indebtedness. "Senior Payment Default"
means any default in the payment of principal of or premium, if any, or interest
on all or any portion of the Senior Indebtedness.

                            In addition, in the event that any Senior
Nonmonetary Default (as defined below) shall have occurred and be continuing,
then, upon the receipt by the Company of written notice of such Senior
Nonmonetary Default from any holder, or a trustee on behalf of a holder of such
Senior Indebtedness, of the Senior Indebtedness to which such Senior Nonmonetary
Default relates, then the Company may not directly or indirectly, make any
payments in respect of the Debentures (other than payment of interest in shares
of Junior Securities or payment of other subordinated securities issued in a
reorganization proceeding, each as provided in the fourth paragraph of Section
14.2 or payments from funds previously segregated or deposited in trust to
redeem or repurchase the Debentures under this Purchase Agreement) during the
period (the "Payment Blockage Period") commencing on the date of such receipt by
the Company of such written notice and ending on the earlier of (i) the date, if
any, on which the Senior Indebtedness to which such Senior Nonmonetary Default
relates is discharged or such Senior Nonmonetary Default shall have been cured
or waived in writing or shall have ceased to exist and any acceleration of
Senior Indebtedness to which such Senior Nonmonetary Default relates shall have
been rescinded or annulled and (ii) the one hundred seventy-ninth (179th) day
after the date of such receipt of such written notice. Notwithstanding anything
in this Agreement to the contrary, no more than one Payment Blockage Period may
be commenced with respect to the Debentures during any period of three hundred
sixty (360) consecutive days and there shall be a period of at least one hundred
eighty (180) consecutive days in each period of three hundred sixty (360)
consecutive days when no Payment Blockage Period is in effect. Following the
commencement of any Payment Blockage Period, the holders of Senior Indebtedness
shall be precluded from commencing a subsequent Payment Blockage Period until
the conditions set forth in the preceding sentence shall have been satisfied.
For all purposes of this paragraph, no Senior Nonmonetary Default that existed
or was continuing (it being acknowledged that any subsequent action that would
give rise to an event of default pursuant to any provision under which an event
of default previously existed or was continuing shall constitute a new event of
default for this purpose) on the date of commencement of any Payment Blockage
Period with respect to the Senior Indebtedness initiating such Payment Blockage
Period shall be, or may be made, the basis for the commencement of a subsequent
Payment Blockage Period with respect to the Senior Indebtedness initiating such
blockage period unless such Senior Nonmonetary Default shall have been cured or

waived for a period of not less than ninety (90) consecutive days. "Senior
Nonmonetary Default" means any default (other than a Senior Payment Default) or
any event (other than a Senior Payment Default) which, after notice or lapse or
time (or both), would become an event of default, under the terms of any Senior
Indebtedness permitting one or more holders of such Senior Indebtedness or a
trustee or agent on behalf of a holder of

                                      -43-

<PAGE>



Senior Indebtedness to declare such Senior Indebtedness due and payable prior to
the date on which it would otherwise become due and payable.

                            In the event that, notwithstanding the foregoing,
the Company shall make any Debenture Payment to any holder prohibited by the
foregoing provisions of this Section 14.3, then and in such event the Company
shall promptly notify the holders of Senior Indebtedness of such prohibited
payment and such payment shall be held in trust for the benefit of, and such
Debenture Payment shall be paid over and delivered forthwith to the Company for
the benefit of the holders of Senior Indebtedness.

                            The provisions of this Section shall not apply to
any Debenture Payment with respect to which Section 14.2 would be applicable.

                  14.4. Payment Permitted If No Default. Nothing contained in
this Section 14 or in any of the Debentures insofar as they incorporate the
provisions of this Section 14 shall prevent the Company, at any time except
during the pendency of any Proceeding referred to in Section 14.2 or under the
conditions described in Section 14.3, from making Debenture Payments.

                  14.5. Subrogation to Rights of Holders of Senior Indebtedness.
Subject to the payment in full of all amounts due or to become due on or in
respect of Senior Indebtedness, or the provision for such payment in cash or
cash equivalents or otherwise in a manner satisfactory to the holders of Senior
Indebtedness, the holders of the Debentures shall be subrogated to the rights of
the holders of such Senior Indebtedness to receive payments and distributions of
cash, property and securities applicable to the Senior Indebtedness until the
principal of and interest on the Debentures shall be paid in full. For purposes
of such subrogation, no payments or distributions to the holders of the Senior
Indebtedness of any cash, property or securities to which the holders of the
Debentures would be entitled except for the provisions of this Section 14, and
no payments over pursuant to the provisions of this Section 14 to the holders of
Senior Indebtedness by holders of the Debentures shall, as among the Company,
its creditors other than holders of Senior Indebtedness and the holders of the
Debentures, be deemed to be a payment or distribution by the Company to or on
account of the Senior Indebtedness.

                  14.6. Provisions Solely to Define Relative Rights. The
provisions of this Section 14 are and are intended solely for the purpose of
defining the relative rights of the holders of the Debentures on the one hand
and the holders of Senior Indebtedness on the other hand. Nothing contained in

this Section 14 or elsewhere in this Agreement or in the Debentures is intended
to or shall (a) impair, as among the Company, its creditors other than holders
of Senior Indebtedness and the holders of the Debentures, the obligation of the
Company, which is absolute and unconditional, to pay to the holders of the
Debentures the principal of and interest on the Debentures as and when the same
shall become due and payable in accordance with their terms; (b) affect the
relative rights against the Company of the holders of the Debentures and
creditors of the Company other than the holders of Senior Indebtedness; or

                                      -44-

<PAGE>



(c) prevent the holder of any Debenture from exercising all remedies otherwise
permitted by applicable law upon default under this Agreement subject to the
rights, if any, under this Section 14 of the holders of Senior Indebtedness to
receive cash, property and securities otherwise payable or deliverable to such
holder.

                  14.7. Enforcement of Subordination By Holders of Senior Notes;
No Waiver of Subordination Provisions. Each holder of a Debenture by his
acceptance thereof, if and so long as a Debenture Payment is prohibited under
this Section 14, irrevocably authorizes and empowers (but without imposing any
obligation on, or any duty to such holder from) each holder of Senior Notes at
any time outstanding, and such holder's representatives, to demand, sue for,
collect and receive such holder's ratable share of Debenture Payments which are
required to be paid or delivered to the holders of Senior Indebtedness as
provided in this Section 14 in any liquidation or reorganization of the Company
under the U.S. Federal Bankruptcy Code (an "Insolvency Proceeding"), (A) to file
a proof of claim or debt in the form required in an Insolvency Proceeding
respecting such holder of Senior Notes' ratable share of such Debenture Payments
in any Insolvency Proceeding in the name of such holders of Debentures, and to
prove the validity, amount and priority of such claim, and agrees that such
holder is an authorized agent for purposes of Federal Rule of Bankruptcy
Procedure 3001(b) (provided, however, if, and to the extent that, the holders of
the Senior Notes (or their representatives) have not filed a proof of claim or
interest with respect to the Debentures in any action or case under the Federal
Bankruptcy Code at least five (5) Business Days prior to the last date by which
all such proofs of claim or interest must be filed or forever barred, the
holders of the Debentures or their representatives may (but shall not be
obligated to) file proofs of claim or interest with respect to the Debentures);
(B) to vote the claim respecting such holder of Senior Notes' ratable share of
such Debenture Payments in any Insolvency Proceeding, including, without
limitation, in a proceeding under Chapter 11, Title 11, United States Code; and
(C) to take any such actions as such holder of Senior Notes, or such holder's
representatives, may determine to be reasonably necessary or appropriate for the
enforcement of the provisions set forth in (A) or (B) above.

                            No right of any present or future holder of any
Senior Indebtedness to enforce subordination as herein provided shall at any
time in any way be prejudiced or impaired by any act or failure to act on the
part of the Company or by any act or failure to act, in good faith, by any such

holder, or by any noncompliance by the Company with the terms, provisions and
covenants of this Agreement, regardless of any knowledge thereof any such holder
may have or be otherwise charged with.

                            Without in any way limiting the generality of the
foregoing paragraph, the holders of Senior Indebtedness may, at any time and
from time to time, without the consent of or notice to the holders of the
Debentures, without incurring responsibility to the holders of the Debentures
and without impairing or releasing the subordination provided in this Section 14
or the obligations hereunder of the holders of the Debentures to the holders of
Senior Indebtedness, do any one or more of the following: (i) amend or
supplement in any manner Senior Indebtedness or any instrument evidencing the
same or any agreement under which Senior Indebtedness is outstanding; (ii) sell,
exchange, release or otherwise deal with any property

                                      -45-

<PAGE>



pledged, mortgaged or otherwise securing Senior Indebtedness; (iii) release any
Person liable in any manner for the collection of Senior Indebtedness; and (iv)
exercise or refrain from exercising any rights against the Company and any other
Person.

                  14.8. Reliance on Judicial Order or Certificate of Liquidating
Agent. Upon any payment or distribution of assets of the Company referred to in
this Section 14, the holders of the Debentures shall be entitled to rely upon
any order or decree entered by any court of competent jurisdiction in which such
Proceeding is pending, or a certificate of the trustee in bankruptcy, receiver,
liquidating trustee, custodian, assignee for the benefit of creditors, agent or
other Person making such payment or distribution, delivered to the holders of
Debentures, for the purpose of ascertaining the Persons entitled to participate
in such payment or distribution, the holders of the Senior Indebtedness and
other indebtedness of the Company, the amount thereof or payable thereon, the
amount or amounts paid or distributed thereon and all other facts pertinent
thereto or to this Section 14.

                  14.9. Certain Conversions Deemed Payment. For the purposes of
this Section 14 only, (i) the issuance and delivery of Junior Securities upon
conversion of Debentures in accordance with Section 15 hereof shall not be
deemed to constitute a Debenture Payment and (ii) the payment, issuance or
delivery of cash, property or securities (other than Junior Securities) upon
conversion of a Debenture shall be deemed to constitute a Debenture Payment. For
the purposes of this Section 14, the term "Junior Securities" means shares of
any Capital Stock. Nothing contained in this Section 14 or elsewhere in this
Agreement or in the Debentures is intended to or shall impair, as among the
Company, its creditors other than holders of Senior Indebtedness and the holders
of the Debentures, the right, which is absolute and unconditional, of the holder
of any Debenture to convert such Debenture in accordance with the provisions of
Section 15 hereof.

                  14.10. Not to Prevent Events of Default. The failure to make a

payment on account of principal of premium, if any, or interest on the
Debentures by reason of any provision of this Section 14 will not be construed
as preventing the occurrence of an Event of Default.

         15.      Conversion Rights.

                  15.1. Conversion Privilege and Conversion Rate. Subject to and
upon compliance with the provisions of this Section 15, at the option of the
holder thereof, any Debenture may be converted into fully paid and nonassessable
shares (calculated as to each conversion to the nearest one one-hundredth
(1/100th) of a share) of Common Stock at the Conversion Rate, determined as
hereinafter provided, in effect at the time of conversion. Such conversion right
shall commence on the date of such Debenture and expire the later of (i) at the
close of business on February 1, 2012 or (ii) the date the full principal amount
of all of the Debentures and all accrued interest thereon have been paid in
full. In case any Debentures are called for redemption under Section 11.2 or
11.3 or the Company requires holders of Notes to

                                      -46-

<PAGE>



make a Mandatory Sale under Section 11.4, such conversion right in respect of
any such Debenture shall be subject to the provisions of Section 11.5.

                            The rate at which shares of Common Stock shall be
delivered upon conversion (herein called the "Conversion Rate") shall be
initially 71.42857 shares of Common Stock for each $1,000 principal amount of
Debentures. The Conversion Rate shall be adjusted in certain instances as
provided in this Section 15.

                  15.2. Exercise of Conversion Privilege; Time Conversion Deemed
Effected; Delivery of Stock Certificates; Partial Conversions; Accrued Interest.
In order to exercise the conversion privilege, the holder of any Debenture to be
converted shall surrender such Debenture, duly endorsed or assigned to the
Company or in blank, at the Company's principal executive offices, 2440 Research
Boulevard, Suite 400, Rockville, Maryland 20850 (or such other office or agency
of the Company as the Company may designate by notice in writing to each holder
of Debentures), accompanied by written notice to the Company at such office that
the holder elects to convert such Debenture or, if less than the entire
principal amount thereof is to be converted, the portion thereof to be
converted.

                            A Debenture shall be deemed to have been converted
immediately prior to the close of business on the day of surrender of such
Debenture for conversion in accordance with the foregoing provisions, and at
such time the rights of the holder of such Debenture, as a holder thereof, shall
cease to the extent of the portion of such Debenture converted, and the Person
or Persons entitled to receive the Conversion Shares shall be treated for all
purposes as the record holder or holders thereof at such time. As promptly as
practicable on or after the date of any conversion in full or in part of any
Debenture, but in no event later than five (5) Business Days thereafter, the

Company shall, at its expense (including the payment by it of any applicable
issue taxes), issue and deliver to the holder of such Debenture, or as such
holder may direct, a certificate or certificates for the number of full
Conversion Shares, together with (a) payment in lieu of any fraction of a share,
as provided in Section 15.3, and (b) interest (payable in the form of Interest
Shares as provided in the form of the Debenture) on the principal amount of such
Debenture, or the portion thereof converted, accrued and unpaid to and including
the date of such conversion, without any adjustment in respect of any dividend
or other distribution payable on the Conversion Shares.

                            Upon any partial conversion of a Debenture, the
Company will forthwith issue and deliver to or upon the order of the holder
thereof, at the expense of the Company, a new Debenture or Debentures in
aggregate principal amount equal to the unpaid and unconverted portion of the
principal amount of such partially converted Debenture. Such new Debenture or
Debentures shall be registered in the name of such holder and dated as of the
date of the converted Debenture.

                  15.3. Fractions of Shares. No fractional shares of Common
Stock shall be issued upon conversion of any Debenture or Debentures. If more
than one (1) Debenture shall be surrendered for conversion at one time (or
substantially at the same time) by the same holder,

                                      -47-

<PAGE>



the number of full shares which shall be issuable upon conversion thereof shall
be computed on the basis of the aggregate principal amount of the Debentures so
surrendered. In place of any fractional share of Common Stock which would
otherwise be issuable upon conversion of any Debenture or Debentures, the
Company shall calculate and pay a cash adjustment in respect of such fraction
(calculated to the nearest one one-hundredth (1/100th) of a share) in an amount
equal to the same fraction of the current market price per share of Common Stock
(calculated in accordance with Section 15.4(8) below) at the close of business
on the day of conversion.

                  15.4. Adjustments to Conversion Rate. The Conversion Rate
shall be subject to adjustments from time to time as follows:

                            (1) In case at any time after the Closing Date the
         Company shall pay or make a dividend or other distribution on any class
         of Capital Stock of the Company (other than the Series C Preferred
         Stock) in shares of its Common Stock, the Conversion Rate in effect at
         the opening of business on the day following the date fixed for the
         determination of stockholders entitled to receive such dividend or
         other distribution shall be increased by dividing such Conversion Rate
         by a fraction of which the numerator shall be the number of shares of
         Common Stock outstanding at the close of business on the date fixed for
         such determination and the denominator shall be the sum of such number
         of shares and the total number of shares constituting such dividend or
         other distribution, such increase to become effective immediately after

         the opening of business on the day following the date fixed for such
         determination. For the purposes of this paragraph (1), the number of
         shares of Common Stock at any time outstanding shall not include shares
         held in the treasury of the Company but shall include shares issuable
         in respect of scrip certificates issued in lieu of fractions of shares
         of Common Stock. The Company will not pay any dividend or make any
         distribution on shares of Common Stock held in the treasury of the
         Company.

                            (2) In case at any time after the Closing Date, the
         Company shall issue rights or warrants to all holders of its Common
         Stock (not being available on an equivalent basis to holders of the
         Debentures upon conversion) entitling them to subscribe for or purchase
         shares of Common Stock at a price per share less than the current
         market price per share (determined as provided in paragraph (8) of this
         Section 15.4) of the Common Stock on the date fixed for the
         determination of stockholders entitled to receive such rights or
         warrants, the Conversion Rate in effect at the opening of business on
         the day following the date fixed for such determination shall be
         increased by dividing such Conversion Rate by a fraction of which the
         numerator shall be the number of shares of Common Stock outstanding at
         the close of business on the date fixed for such determination plus the
         number of shares of Common Stock which the aggregate of the offering
         price of the total number of shares of Common Stock so offered for
         subscription or purchase would purchase at such current market price
         and the denominator shall be the number of shares of Common Stock
         outstanding at the close of business on the date fixed for such
         determination plus the number of shares of Common Stock so offered for
         subscription or purchase, such increase to become effective immediately
         after the opening

                                      -48-

<PAGE>



         of business on the day following the date fixed for such determination.
         However, upon the expiration of any right or warrant to purchase Common
         Stock the issuance of which resulted in an adjustment in the Conversion
         Rate pursuant to this subsection (2), if any such right or warrant
         shall expire and shall not have been exercised, the Conversion Rate
         shall immediately upon such expiration be recomputed and effective
         immediately upon such expiration be increased to the price which it
         would have been (but reflecting any other adjustments in the Conversion
         Rate made pursuant to the provisions of this Section 15.4 after the
         issuance of such rights or warrants) had the adjustment of the
         Conversion Rate made upon the issuance of such rights or warrants been
         made on the basis of offering for subscription or purchase only that
         number of shares of Common Stock actually purchased upon the exercise
         of such rights or warrants actually exercised. For the purposes of this
         paragraph (2), the number of shares of Common Stock at any time
         outstanding shall not include shares held in the treasury of the
         Company but will include shares issuable in respect of scrip

         certificates issued in lieu of fractions of shares of Common Stock. The
         Company will not issue any rights or warrants in respect of shares of
         Common Stock held in the treasury of the Company.

                            (3) In case at any time after the Closing Date,
         outstanding shares of Common Stock shall be subdivided into a greater
         number of shares of Common Stock, the Conversion Rate in effect at the
         opening of business on the day following the day upon which such
         subdivision becomes effective shall be proportionately increased and,
         conversely, in case at any time after the date hereof, outstanding
         shares of Common Stock shall each be combined into a smaller number of
         shares of Common Stock, the Conversion Rate in effect at the opening of
         business on the day following the day upon which such combination
         becomes effective shall be proportionately reduced, such increase or
         reduction, as the case may be, to become effective immediately after
         the opening of business on the day following the day upon which such
         subdivision or combination becomes effective.

                            (4) In case at any time after the Closing Date, the
         Company shall, by dividend or otherwise, distribute to all holders of
         its Common Stock evidences of its indebtedness or assets (including
         stock or other securities of the Company or any other issuer, but
         excluding any rights or warrants referred to in paragraph (2) of this
         Section 15.4, any dividend or distribution paid exclusively in cash and
         any dividend or distribution referred to in paragraph (1) of this
         Section 15.4), the Conversion Rate shall be adjusted so that the same
         shall equal the rate determined by dividing the Conversion Rate in
         effect immediately prior to the close of business on the date fixed for
         the determination of stockholders entitled to receive such distribution
         by a fraction of which the numerator shall be the current market price
         per share (determined as provided in paragraph (8) of this Section
         15.4) of the Common Stock on the date fixed for such determination less
         the then fair market value (each reference to "fair market value" in
         this Section 15.4 shall mean the fair market value as determined by the
         Board of Directors of the Company in good faith, whose determination
         shall be described in a Board Resolution, a copy of which shall be
         delivered to each holder of Debentures within

                                      -49-

<PAGE>



         ten (10) days of the adoption of the resolution) of the portion of the
         assets or evidences of indebtedness so distributed applicable to one
         (1) share of Common Stock and the denominator shall be such current
         market price per share of the Common Stock, such adjustment to become
         effective immediately prior to the opening of business on the day
         following the date fixed for the determination of stockholders entitled
         to receive such distribution.

                            (5) In case at any time after the Closing Date (A)
         the Company shall, by dividend or otherwise, distribute to all holders

         of its Common Stock cash (excluding any cash that is distributed upon a
         merger or consolidation to which Section 15.13 applies or as part of a
         distribution referred to in paragraph (4) of this Section 15.4) and
         (B)(I) the total of (x) the aggregate amount of such cash distribution,
         (y) the aggregate amount of any other distributions to all holders of
         its Common Stock made exclusively in cash within the twelve (12) months
         preceding the date of payment of such distribution and in respect of
         which no adjustment pursuant to this paragraph (5) or paragraph (6) of
         this Section 15.4 has been made and (z) the aggregate of any cash plus
         the fair market value of other consideration payable in respect of any
         tender offers by the Company or any of its Subsidiaries for all or any
         portion of the Common Stock concluded within the twelve (12) months
         preceding the date of payment of such distribution and in respect of
         which no adjustment pursuant to this paragraph (5) or paragraph (6) of
         this Section 15.4 has been made, exceeds (II) ten percent (10%) of the
         product of the current market price per share (determined as provided
         in paragraph (8) of this Section 15.4) of the Common Stock on the date
         for the determination of holders of shares of Common Stock entitled to
         receive such distribution times the number of shares of Common Stock
         outstanding on such date, then, and in each such case, immediately
         after the close of business on such date for determination, the
         Conversion Rate shall be increased so that the same shall equal the
         rate determined by dividing the Conversion Rate in effect immediately
         prior to the close of business on the date fixed for determination of
         the stockholders entitled to receive such distribution by a fraction
         (i) the numerator of which shall be equal to such current market price
         per share on the date fixed for such determination less an amount equal
         to the quotient of (X) the sum of (I) the total of the amounts referred
         to in subclauses (B)(I)(x) and (y) of this paragraph (5) and (II) the
         aggregate of the excess of the amount referred to in subclause
         (B)(I)(z) of this paragraph (5) for each tender offer so referred to
         over the aggregate current market price of the shares of Common Stock
         purchased in such tender offer as of the Expiration Time (as
         hereinafter defined) for such tender offer divided by (Y) the number of
         shares of Common Stock outstanding on such date for determination and
         (ii) the denominator of which shall be equal to such current market
         price per share on such date for determination.

                            (6) In case at any time after the Closing Date (A) a
         tender offer made by the Company or any Subsidiary for all or any
         portion of the Common Stock shall expire and (B)(I) the total of (x)
         the fair market value of the aggregate consideration required to be
         paid pursuant to such tender offer (as amended upon the expiration
         thereof) to stockholders (based on the acceptance (up to any maximum
         specified in the

                                      -50-

<PAGE>



         terms of the tender offer) of Purchased Shares (as defined below)), (y)
         the aggregate of the cash plus the fair market value, as of the

         expiration of such tender offer, of consideration payable in respect of
         any other tender offer, by the Company or any Subsidiary for all or any
         portion of the Common Stock expiring within the twelve (12) months
         preceding the expiration of such tender offer and in respect of which
         no adjustment pursuant to this paragraph (6) or paragraph (5) of this
         Section 15.4 has been made and (z) the aggregate amount of any
         distributions to all holders of the Company's Common Stock made
         exclusively in cash within twelve (12) months preceding the expiration
         of such tender offer and in respect of which no adjustment pursuant to
         this paragraph (6) or paragraph (5) of this Section 15.4 has been made,
         exceeds (II) ten percent (10%) of the product of the current market
         price per share of the Common Stock (determined as provided in
         paragraph (8) of this Section 15.4) on the date of the last time (the
         "Expiration Time") tenders could have been made pursuant to such tender
         offer (as it may be amended) times the number of shares of Common Stock
         outstanding (including any tendered shares) on the Expiration Time,
         then, and in each such case, immediately prior to the opening of
         business on the day after the date of the Expiration Time, the
         Conversion Rate shall be adjusted so that the same shall equal the
         price determined by dividing the Conversion Rate immediately prior to
         the close of business on the date of the Expiration Time by a fraction
         (i) the numerator of which shall be equal to (a) the product of (I)
         such current market price per share on the date of the Expiration Time
         and (II) the number of shares of Common Stock outstanding (including
         any tendered shares) as of the Expiration Time less (b) the total of
         the amounts referred to in Clause (B)(I) of this paragraph (6), and
         (ii) the denominator of which shall be equal to the product of (a) such
         current market price per share on the date of the Expiration Time and
         (b) the number of shares of Common Stock outstanding (including any
         tendered shares) as of the Expiration Time less the number of all
         shares validly tendered and not withdrawn as of the Expiration Time
         (the shares deemed so accepted up to any such maximum, being referred
         to as the "Purchased Shares").

                            (7) The reclassification of Common Stock into
         securities other than Common Stock (other than any reclassification
         upon a consolidation or merger to which Section 15.13 applies) shall be
         deemed to involve (a) a distribution of such securities other than
         Common Stock to all holders of Common Stock (and the effective date of
         such reclassification shall be deemed to be "the date fixed for the
         determination of stockholders entitled to receive such distribution"
         and "the date fixed for such determination" within the meaning of
         paragraph (4) of this Section 15.4), and (b) a subdivision or
         combination, as the case may be, of the number of shares of Common
         Stock outstanding immediately prior to such reclassification into the
         number of shares of Common Stock outstanding immediately thereafter
         (and the effective date of such reclassification shall be deemed to be
         "the day upon which such subdivision becomes effective" or "the day
         upon which such combination becomes effective", as the case may be, and
         "the day upon which such subdivision or combination becomes effective"
         within the meaning of paragraph (3) of this Section 15.4).


                                      -51-


<PAGE>



                            (8) For the purpose of any computation under
         paragraph (2), (4), (5) or (6) of this Section 15.4, the current market
         price per share of Common Stock on any date shall be calculated by the
         Company and be deemed to be the average of the daily Closing Price per
         share of Common Stock for the five (5) consecutive Trading Days before,
         and ending not later than, the earlier of (i) the day in question and
         (ii) the day before the "ex" date with respect to the issuance or
         distribution requiring such computation. For purposes of this
         paragraph, the term "'ex' date", when used with respect to any issuance
         or distribution, means the first date on which the Common Stock trades
         regular way on the applicable securities exchange or in the applicable
         securities market without the right to receive such issuance or
         distribution.

                            (9) The Company may make such increases in the
         Conversion Rate, for the remaining term of the Debentures or any
         shorter term, in addition to those required by paragraphs (1), (2),
         (3), (4), (5) and (6) of this Section 15.4, as it considers to be
         advisable in order to avoid or diminish any income tax to any holders
         of shares of Common Stock resulting from any dividend or distribution
         of stock or issuance of rights or warrants to purchase or subscribe for
         stock or from any event treated as such for income tax purposes or for
         any other reasons.

                  15.5. Effect on Conversion Price of Certain Events. In order
to prevent dilution of the conversion rights granted under this Section 15, in
addition to the adjustments provided for in Section 15.4, the Conversion Rate
shall be subject to adjustment from time to time pursuant to this Section 15.5
as follows; provided, however, that no adjustments shall be made under this
Section 15.5 with respect to any issuance of securities or other event that
requires an adjustment of the Conversion Rate under Section 15.4.

                            (1) If and whenever on or after the Closing Date the
         Company issues or sells, or in accordance with this Section 15.5 is
         deemed to have issued or sold, other than in an Excluded Issuance, any
         share of Common Stock for a consideration per share less than the
         Trigger Price in effect immediately prior to such time (a "Dilutive
         Event"), then forthwith upon such issue or sale in the Dilutive Event
         the Conversion Rate shall be increased by dividing the Conversion Rate
         in effect immediately before the Dilutive Event by a fraction, the
         numerator of which is the number of shares of Common Stock that are
         Outstanding on an As-Converted Basis (as defined below) immediately
         before the Dilutive Event plus the number of shares of Common Stock
         that could be purchased at the Trigger Price at the time of the
         Dilutive Event for the aggregate consideration paid or payable upon the
         sale or issuance of Common Stock in the Dilutive Event, and the
         denominator of which is the number of shares of Common Stock that are
         Outstanding on an As-Converted Basis immediately before the Dilutive
         Event plus the number of shares that are acquired or to be acquired

         upon the sale or issuance of the Common Stock in the Dilutive Event.
         For purposes of this paragraph (1), "Outstanding on an As-Converted
         Basis immediately before the Dilutive Event" means the sum of (i) all
         Common Stock issued and outstanding immediately before the Dilutive
         Event plus (ii) all Common Stock

                                      -52-

<PAGE>



         issuable upon the exercise of Options or conversion of Convertible
         Securities outstanding immediately before the Dilutive Event (other
         than the Debentures).

                            (2) If after the Closing Date the Company in any
         manner grants any Options and the price per share for which shares of
         Common Stock are issuable upon the exercise of any such Option is less
         than the Trigger Price in effect immediately prior to the time of the
         granting of such Option, then such shares of Common Stock shall be
         deemed to have been issued and sold by the Company at the time of the
         granting of such Options for such price per share and the Conversion
         Rate shall be adjusted in accordance with paragraph (1) of this Section
         15.5. For purposes of this paragraph, the "price per share" for which
         shares of Common Stock are issuable upon the exercise of any Option
         shall be equal to the sum of the amounts of consideration (if any)
         received or receivable by the Company with respect to such shares of
         Common Stock upon the granting of the Option and upon exercise of the
         Option. No further adjustment of the Conversion Rate shall be made upon
         the actual issue of such Common Stock upon the exercise of such
         Options.

                            (3) If after the Closing Date the Company in any
         manner issues or sells any Convertible Security (or Options to purchase
         any Convertible Security) and the price per share for shares of Common
         Stock that are issuable upon conversion or exchange thereof is less
         than the Trigger Price in effect immediately prior to the time of such
         issue or sale (or the granting of such Option), then such shares of
         Common Stock shall be deemed to have been issued and sold by the
         Company at the time of the issuance or sale of such Convertible
         Securities (or the granting of such Option) for such price per share
         and the Conversion Price shall be adjusted in accordance with paragraph
         (1) of this Section 15.5. For the purposes of this paragraph (3), the
         "price per share" for which shares of Common Stock are issuable upon
         conversion or exchange of any Convertible Security (or exercise of any
         Option therefor) shall be equal to the sum of the amounts of
         consideration (if any) received or receivable by the Company upon the
         issuance of the Convertible Security (or such Option) and upon the
         conversion or exchange of such Convertible Security (or exercise of
         such Option). No further adjustment of the Conversion Price shall be
         made upon the actual issue of such Common Stock upon conversion or
         exchange of any Convertible Security, and if any such issue or sale of
         such Convertible Security is made upon exercise of any Options for

         which adjustments of the Conversion Rate had been or are to be made
         pursuant to other provisions of this Section 15, no further adjustment
         of the Conversion Rate shall be made by reason of such issue or sale.

                            (4) If after the Closing Date the purchase price
         provided for in any Option, the additional consideration (if any)
         payable upon the issue, conversion or exchange of any Convertible
         Security (other than the Debentures), or the rate at which any
         Convertible Security (other than the Debentures) is convertible into or
         exchangeable for Common Stock changes at any time, any Conversion Rate
         previously adjusted with respect to such Option or Convertible Security
         (other than the Debentures) and in effect

                                      -53-

<PAGE>



         at the time of such change shall be readjusted to the Conversion Rate
         which would have been in effect at such time had such Option or
         Convertible Security (other than the Debentures) originally provided
         for such changed purchase price, additional consideration or changed
         conversion rate, as the case may be, at the time initially granted,
         issued or sold.

                            (5) Upon the expiration of any Option or the
         termination of any right to convert or exchange any Convertible
         Security (other than the Debentures), after the Closing Date, without
         the exercise of any such Option or right, any Conversion Rate then in
         effect hereunder shall be adjusted to the Conversion Rate which would
         have been in effect at the time of such expiration or termination had
         such Option or Convertible Security, to the extent outstanding
         immediately prior to such expiration or termination, never been issued.

                            (6) For the purpose of this Section 15.5, if any
         Common Stock, Option or Convertible Security is issued or sold or
         deemed to have been issued or sold for cash, the consideration received
         therefor shall be deemed to be the amount received by the Company
         therefor. In case any Common Stock, Options or Convertible Securities
         are issued or sold for a consideration other than cash, the amount of
         the consideration other than cash received by the Company shall be the
         fair value of such consideration, except where such consideration
         consists of securities, in which case the amount of consideration
         received by the Company shall be the Market Price thereof as of the
         date of receipt. If any Common Stock, Option or Convertible Security is
         issued to the owners of the non-surviving entity in connection with
         any merger in which the Company is the surviving corporation, the
         amount of consideration therefor shall be deemed to be the fair value
         of such portion of the assets and business of the non-surviving entity
         as is attributable to such Common Stock, Options or Convertible
         Securities, as the case may be. The fair value of any consideration
         other than cash and securities shall be as determined in good faith by
         the Board of Directors of the Company. For purposes of this paragraph

         (6), the term "Market Price" of a security means, with respect to a
         specified date, the Closing Price of such security, averaged over a
         period of the twenty (20) consecutive Business Days prior to such date;
         provided that if during this period such security is not listed on any
         securities exchange, quoted on the Nasdaq National Market, or quoted in
         the over-the-counter market, the Market Price will be the fair value of
         such security determined by agreement between the Company and the
         holders of a majority of the Outstanding Debentures. If such parties
         are unable to reach agreement within a reasonable period of time, the
         fair value of such security shall be determined by an independent
         appraiser experienced in valuing such type of consideration jointly
         selected by the Company and the holders of a majority of the
         Outstanding Debentures. The determination of such appraiser shall be
         final and binding upon the parties, and the fees and expenses of such
         appraiser shall be borne by the Company.

                            (7) In case any Option is issued in connection with
         the issue or sale of other securities of the Company, together
         comprising one (1) integrated transaction in

                                      -54-

<PAGE>



         which no specific consideration is allocated to such Option by the
         parties thereto, the Option shall be deemed to have been issued for a
         consideration of $.01.

                  15.6. De Minimis Adjustments. Notwithstanding any other
provisions of this Section 15, the Company shall not be required to make any
adjustment of the Conversion Rate unless such adjustment would require an
increase or decrease of at least one percent (1%) in the Conversion Rate as then
in effect. Any lesser adjustment shall be carried forward and shall be made no
later than the time of, and together with, the next subsequent adjustment which,
together with any adjustment or adjustments so carried forward, shall amount to
an increase or decrease of at least one percent (1%) of the Conversion Rate as
then in effect.

                  15.7. Notice of Adjustments of Conversion Rate. Whenever the
Conversion Rate is adjusted as provided in Section 15.4 or Section 15.5, the
Company shall promptly (and, in any event, not later than the fifteenth (15th)
day following the occurrence of the event requiring such adjustment) compute the
adjusted Conversion Rate in accordance with this Section 15 and shall prepare a
report setting forth such adjustment and showing in detail the method of
calculation and the facts upon which such adjustment is based, including a
statement of (a) the consideration received or to be received by the Company for
any additional shares of Common Stock issued or sold or deemed to have been
issued, (b) the number of shares of Common Stock outstanding or deemed to be
outstanding, and (c) the Conversion Rate in effect immediately prior to such
issue or sale and as adjusted on account therefor and, upon the request of any
holder of the Debentures, shall cause certified public accountants of recognized
national standing (which may be the regular auditors of the Company) selected by

the Company to verify such computation and report, if not previously verified at
the request of any holder. The Company will promptly (and, in any event, not
later than such fifteenth (15th) day) furnish a copy of each such report and
such verification to the holder of any Debenture, and will, upon the written
request at any reasonable time of the holder of any Debenture, furnish to such
holder a like report setting forth the Conversion Rate at the time in effect and
showing how it was calculated. The Company will also keep copies of all such
reports and such verifications at its principal office, and will cause the same
to be available for inspection at such office during normal business hours by
the holder of any Debenture or any prospective purchaser of any Debenture
designated by the holder of such Debenture.

                  15.8.     Notice of Certain Corporate Action.   In case:

                            (1) the Company shall declare a dividend (or any
         other distribution) on its Common Stock payable otherwise than in cash
         out of its earned surplus; or

                            (2) the Company shall authorize the granting to all
         holders of its Common Stock of rights or warrants to subscribe for or
         purchase any shares of Capital Stock or of any other rights; or

                            (3) (a) of any reclassification of the Common Stock
         of the Company, or (b) of any consolidation, merger or share exchange
         to which the Company is a party

                                      -55-

<PAGE>



         and for which approval of any stockholders of the Company is required,
         or (c) of any tender offer by the Company or any Subsidiary for all or
         any portion of the Common Stock, or (d) of the conveyance, transfer,
         sale or lease of all or substantially all of the assets of the Company;
         or

                            (4) of the voluntary or involuntary dissolution,
         liquidation or winding up of the Company;

then the Company, ten (10) Business Days prior to the applicable record,
expiration or effective date hereinafter specified, shall give to each holder of
Debentures a notice stating (x) the date on which a record is to be taken for
the purpose of such dividend, distribution, rights or warrants, or, if a record
is not to be taken, the effective date as of which the holders of Common Stock
of record to be entitled to such dividend, distribution, rights or warrants are
to be determined, (y) the date on which the right to make tenders under such
tender offer expires or (z) the date on which such reclassification,
consolidation, merger, share exchange, conveyance, transfer, sale, lease,
dissolution, liquidation or winding up is expected to become effective, and the
date as of which it is expected that holders of Common Stock of record shall be
entitled to exchange their shares of Common Stock for securities, cash or other
property deliverable upon such reclassification, consolidation, merger, share

exchange, conveyance, transfer, sale, lease, dissolution, liquidation or winding
up.

                  15.9. Company to Reserve Common Stock. The Company shall at
all times reserve and keep available, free from preemptive rights, out of its
authorized but unissued Common Stock, for the purpose of effecting the
conversion of Debentures, the full number of Conversion Shares then issuable
upon the conversion of all outstanding Debentures.

                  15.10. Taxes on Conversions. The Company will pay any and all
taxes (other than taxes on income), liens and other charges that may be payable
in respect of the issue or delivery of Conversion Shares pursuant hereto.

                  15.11. Agreements as to Common Stock; Listing. The Company
agrees that all Conversion Shares, upon delivery thereof, will have been duly
authorized and validly issued and will be fully paid and nonassessable with no
liability on the part of holders thereof. The Company will take all such action
as may be necessary to insure that such Conversion Shares may be issued without
violation of any applicable law or regulation, or of any agreement, contract or
understanding applicable to the Company or its assets, or of any requirements of
any securities exchange or automated quotation system upon which any shares of
Common Stock may be listed or quoted.

                            No class of Capital Stock (other than any class that
has a preference in respect of dividends or of amounts payable in the event of
any voluntary or involuntary liquidation, dissolution or winding up of the
Company or that is subject to redemption by the Company) shall have voting
rights that are proportionately greater per share than those of any

                                      -56-

<PAGE>



class of Capital Stock issuable on any conversion of the Debentures pursuant
hereto, and all classes of which shares are so issuable on any such conversion
shall have voting rights.

                  15.12. Cancellation of Converted Debentures. All Debentures
delivered for conversion shall be cancelled and no such Debenture shall
thereafter be reissued.

                  15.13. Provision in Case of Consolidation, Merger or
Conveyance of Assets.

                            (a) In case at any time after the Closing Date the
Company shall be a party to any transaction (including, without limitation, a
merger, consolidation, sale of all or substantially all of the Company's assets
or recapitalization of the Common Stock) in which the previously outstanding
Common Stock shall be changed into or exchanged for different securities of the
Company, common stock or other securities of another corporation or interests in
a noncorporate entity or other property (including cash) or any combination of
any of the foregoing (each such transaction being hereinafter referred to as a

"Reorganization Transaction," the date of the consummation of the Reorganization
Transaction being hereinafter referred to as the "Consummation Date," the
Company (in the case of a recapitalization of the Common Stock) or such other
corporation or entity (in each other case) being hereinafter referred to as the
"Acquiring Company," and the common stock (or equivalent equity interests) of
the Acquiring Company being hereinafter referred to as the "Acquirer's Common
Stock"), then, subject to the alternate rights of each holder of Debentures set
forth in Section 15.13(b), if then applicable as a condition to the consummation
of the Reorganization Transaction, lawful and adequate provisions shall be made
so that, upon the basis and the terms and in the manner provided in this Section
15, each holder of a Debenture, upon the conversion thereof at any time after
the consummation of the Reorganization Transaction, shall be entitled to
receive, in lieu of the Stock or Other Securities issuable upon such conversion
prior to such consummation, the stock and other securities, cash and property to
which such holder would have been entitled upon the consummation of the
Reorganization Transaction if such holder had converted such Debenture
immediately prior thereto (subject to adjustments from and after the
Consummation Date as nearly equivalent as possible to the adjustments provided
for in this Section 15 including, without limitation, this Section 15.13).

                            (b) In addition to the rights granted in Section
15.13(a), at the election of any holder of any Debenture pursuant to notice
given to the Company on or before the later of (x) the day on which the holders
of the Common Stock of the Company approve the Reorganization Transaction, and
(y) the sixtieth day (60th) following the date of delivery or mailing to such
holder of the last proxy statement relating to the vote on the Reorganization
Transaction by the holders of the Common Stock of the Company, such holder shall
have the right to elect to receive on the Consummation Date and, as a condition
precedent to the Reorganization Transaction, in full payment and in
consideration for the surrender of such Debenture, a cash amount equal to the
current market value (as determined in accordance with Section 15.4(8)) of the
number of shares of Stock (or Other Securities) to which the holder of such
Debenture would have been entitled had such holder converted such Debenture
immediately

                                      -57-

<PAGE>



prior to the consummation of the Reorganization Transaction; provided, however,
that the provisions of this Section 15.13(b) shall not apply prior to the Senior
Notes Reduction Date.

                            (c) The Company will not enter into or be a party to
any Reorganization Transaction following the consummation of which any holder of
Debentures would be entitled in accordance with the foregoing provisions of this
Section 15.13 to receive Acquirer's Common Stock or other securities of the
Acquiring Company upon conversion of such Debentures unless, immediately
following the consummation thereof on the Consummation Date, all of the
following requirements are fulfilled as to the Acquiring Company:

                            (A) its common stock is listed on the New York Stock

                  Exchange or the American Stock Exchange or is authorized for
                  quotation on the Nasdaq National Market as a national market
                  security and such common stock continues to meet the
                  requirements for such listing or quotation, as the case may
                  be, and

                            (B) it is required to file reports with the
                  Commission pursuant to Section 13 or 15(d) of the Exchange
                  Act.

                            (d) Notwithstanding anything contained in this
Agreement to the contrary, the Company will not effect any Reorganization
Transaction unless, prior to the consummation thereof, each corporation or
entity (other than the Company) which may be required to deliver any stock,
securities, cash or property upon the conversion of any Debenture as provided
herein shall assume, by written instrument delivered to the holder of such
Debenture, the obligation to deliver to such holder such shares of stock,
securities, cash or property as, in accordance with the foregoing provisions,
such holder may be entitled to receive, and such corporation or entity shall
have similarly delivered to such holder an opinion of counsel for such
corporation or entity, which counsel shall be reasonably satisfactory to such
holder, stating that such Debenture shall thereafter continue in full force and
effect and the terms hereof (including, without limitation, all of the
provisions of this Section 15) shall be applicable to the stock, securities,
cash or property which such corporation or entity may be required to deliver
upon the exercise hereof. Nothing in this Section 15.13 shall be deemed to
authorize the Company to enter into any transaction not otherwise permitted by
either Section 12.6 or Section 13.1, as then applicable.

                  15.14. Other Dilutive Events. In case any event shall occur
which is substantially similar to the events described in the other provisions
of this Section 15, but as to which substantially similar event such provisions
of this Section 15 are not applicable and in respect of which substantially
similar event the failure to make any adjustment would not in the reasonable
opinion of any holder of a Debenture or the Company fairly protect the
conversion rights granted by this Section 15 in accordance with the essential
intent and principles hereof, then, in each such case, upon the written request
of such holder or on its own motion, the Company shall appoint a firm of
independent certified public accountants of recognized national standing (which
may be the regular auditors of the Company) which shall give their opinion as to
the adjustment, if any, on a basis consistent with the essential intent and
principles established

                                      -58-

<PAGE>



in this Section 15, necessary to preserve, without dilution, such conversion
rights. Upon receipt of such opinion, the Company will promptly mail a copy
thereof to the holder of each Debenture and shall make the adjustments or
increases described therein.


                  15.15. Continuing Obligation of the Company. The Company will,
at the time of conversion of any Debenture in full or in part, upon the request
of any holder thereof, acknowledge in writing its continuing obligation to
afford such holder any rights (including, without limitation, any right of
registration of the Conversion Shares) to which such holder shall continue to be
entitled after such conversion in accordance with the provisions of this
Agreement; provided, however, that if any such holder shall fail to make any
such request, such failure shall not affect the continuing obligation of the
Company to afford to such holder all such rights.

         16.      Registration, Transfer and Substitution of Debentures.

                  16.1. Debenture Register; Ownership of Registered Debentures.
The Company will keep at its principal office a register in which the Company
will provide for the registration of Debentures and the registration of
transfers of Debentures. The Company may treat the Person in whose name any
Debenture is registered on such register as the owner and holder thereof for the
purpose of receiving payment of the principal of and the premium, if any, and
interest on such Debenture and for all other purposes, whether or not such
Debenture shall be overdue, and the Company shall not be affected by any notice
to the contrary. The Company may treat the Person in whose name any Stock is
registered in the stock transfer records of the Company as the owner and holder
thereof for the purpose of receiving dividends and other distributions thereon
and for all other purposes, and the Company shall not be affected by any notice
to the contrary.

                  16.2. Transfer and Exchange of Debentures. Upon surrender of
any Debenture for registration of transfer or for exchange to the Company at its
principal office with evidence that all applicable transfer taxes have been
paid, the Company at its expense will execute and deliver in exchange therefor a
new Debenture or Debentures in denominations of at least $100,000 (except one
(1) Debenture may be issued in a lesser principal amount if the unpaid principal
amount of the surrendered Debenture is not evenly divisible by, or is less than,
$100,000), as requested by the holder or transferee, which aggregate the unpaid
principal amount of such surrendered Debenture. Each such new Debenture shall be
registered in the name of such Person, or its nominee, as such holder or
transferee may request, dated so that there will be no loss of interest on such
surrendered Debenture and otherwise of like tenor.

                  16.3. Replacement of Debentures. Upon receipt of evidence
reasonably satisfactory to the Company of the loss, theft, destruction or
mutilation of any Debenture and, in the case of any such loss, theft or
destruction, upon delivery of an indemnity bond in such reasonable amount and
form as the Company may determine (or, in the case of any Debenture held by you
or another holder of Debentures, of an indemnity agreement from you or such
other holder reasonably satisfactory to the Company), or, in the case of any
such mutilation, upon the

                                      -59-

<PAGE>




surrender of such Debenture for cancellation to the Company at its principal
office, the Company at its expense will execute and deliver, in lieu thereof, a
new Debenture of like tenor, dated so that there will be no loss of interest on
such lost, stolen, destroyed or mutilated Debenture. Any Debenture in lieu of
which any such new Debenture has been so executed and delivered by the Company
shall not be deemed to be an outstanding Debenture for any purpose of this
Agreement.

         17.      Payment.

                  17.1. Form of Payment. Payments of interest becoming due and
payable on any Debenture shall be made by issuing to the holder thereof fully
paid and nonassessable shares of Common Stock in an amount determined by
multiplying the principal amount of the Debenture by eight and three-fourths
percent (8.75%) per annum (computed on the basis of a 360-day year of twelve
(12) 30-day months) and dividing the resulting product by the Applicable
Divisor. All amounts of principal due on any Debenture and any premium (whether
at Stated Maturity, upon acceleration or otherwise) shall be paid in cash in
U.S. dollars in immediately available funds to the account or accounts specified
by the holder of the Debenture.

                  17.2.     Place of Payment.

                            (a) Payments of interest becoming due and payable on
the Debentures shall be made by delivering a certificate or certificates for
shares of Common Stock in such denomination as the holder may request at the
address specified by such holder to the Company from time to time, by notice
pursuant to Section 23 hereof.

                            (b) Except as otherwise provided in Section 17.3,
payments of principal or premium, if any, becoming due and payable on the
Debentures shall be made at the principal office of the Company, provided,
however, that if at any time the Company does not maintain its principal office
in Rockville, Maryland, the Company, by written notice to each holder of any
Debentures, shall designate the principal office of any bank or trust company in
New York County, State of New York, as the office or agency where such payments
shall be made.

                  17.3. Home Office Payment. So long as you or your nominee
shall be the holder of any Debenture, and notwithstanding anything contained in
Section 17.2 or in such Debenture to the contrary, the Company will pay all sums
becoming due on such Debenture for principal, or premium, if any, in the manner
and at the address specified for such purpose in Schedule I attached hereto, or
in such other manner and at such other address as you shall have from time to
time specified to the Company in writing for such purpose, without the
presentation or surrender of such Debenture or the making of any notation
thereon, except that any Debenture so paid or redeemed or repurchased in full
shall, following such payment, redemption or repurchase, be surrendered to the
Company at its principal office or at the place of payment maintained by the
Company pursuant to Section 17.2 for cancellation. The Company agrees to afford
the benefits of this Section 17.3 to any holder which is the direct or indirect
transferee of any Debenture purchased by you under this Agreement.

                                      -60-


<PAGE>




         18.      Events of Default; Acceleration.

                  18.1. Nature of Events and Acceleration of Debentures. Subject
to Section 18.5, if any of the following events ("Events of Default") shall
occur and be continuing for any reason whatsoever (and whether such occurrence
shall be voluntary or involuntary or come about or be effected by operation of
law or otherwise):

                            (a) any payment of principal or premium, if any, on
         any Debenture is not made when and as such payment becomes due at
         maturity, upon acceleration, redemption or repurchase, or otherwise;

                            (b) any payment of interest on any Debenture is not
         made when and as such payment becomes due and payable, and such default
         continues for a period of fifteen (15) days;

                            (c) the Company fails to comply with the
         requirements for consolidation, merger or conveyance, transfer or lease
         of all or substantially all of the Company's assets, as set forth in
         either Section 12.6 or Section 13.1, as then applicable;

                            (d) the Company fails to comply with or perform any
         of the then-applicable covenants or other agreements set forth in this
         Agreement or the Debentures (other than a default specified in clause
         (a), (b) or (c) above) or any other provision of this Agreement, and
         such failure continues for a period of thirty (30) days after the
         earlier of (1) the day on which a Responsible Officer of the Company
         first obtains knowledge of such failure, or of the events or conditions
         that constitute such failure or (2) the day on which written notice
         thereof is given to the Company by the holder of any Debenture;

                            (e) any warranty or representation by or on behalf
         of the Company contained in this Agreement or in any instrument
         furnished in compliance with this Agreement is false or incorrect in
         any material respect on the date as of which made;

                            (f) any "Event of Default" under (and as defined in)
         either of the Senior Indentures shall have occurred and be continuing;

                            (g) there occurs with respect to any issue or issues
         of Indebtedness of the Company or any Significant Subsidiary having an
         outstanding principal amount of $2 million or more in the aggregate for
         all such issues of all such Persons, whether such Indebtedness now
         exists or shall hereafter be created, (I) an event of default that has
         caused the holder thereof to declare such Indebtedness to be due and
         payable prior to its Stated Maturity and such Indebtedness has not been
         discharged in full or such acceleration has not been rescinded or
         annulled within thirty (30) days of such acceleration and/or (II) the

         failure to make a principal payment at the final (but not any

                                      -61-

<PAGE>



         interim) fixed maturity and such defaulted payment shall not have been
         made, waived or extended within thirty (30) days of such payment
         default;

                            (h) any final judgment or order (not covered by
         insurance) for the payment of money in excess of $2 million in the
         aggregate for all such final judgments or orders against all such
         Persons (treating any deductibles, self-insurance or retention as not
         so covered) shall be rendered against the Company or any Significant
         Subsidiary and shall not be paid or discharged, and there shall be any
         period of sixty (60) consecutive days following entry of the final
         judgment or order that causes the aggregate amount for all such final
         judgments or orders outstanding and not paid or discharged against all
         such Persons to exceed $2 million during which a stay of enforcement of
         such final judgment or order, by reason of a pending appeal or
         otherwise, shall not be in effect;

                            (i) the Company or any of its Significant
         Subsidiaries shall commence a voluntary case under any chapter of the
         Federal Bankruptcy Code, or shall consent to (or fail to contest within
         ten (10) days) the commencement of an involuntary case against the
         Company or any of its Subsidiaries under the Federal Bankruptcy Code;

                            (j) the Company or any Significant Subsidiary shall
         institute proceedings for liquidation, rehabilitation, readjustment or
         composition (or for any related or similar purpose) under any law
         (other than the Federal Bankruptcy Code) relating to financially
         distressed debtors, their creditors or property, or shall consent to
         (or fail to contest within ten (10) days) the institution of any such
         proceedings against the Company or any of its Subsidiaries;

                            (k) the Company or any of its Significant
         Subsidiaries shall be insolvent (within the meaning of any applicable
         law), or shall be unable, or shall admit in writing its inability, to
         pay its debts generally as they come due, or shall make an assignment
         for the benefit of creditors or enter into any arrangement for the
         adjustment or composition of debts or claims;

                            (l) a court or other governmental authority or
         agency having jurisdiction in the premises shall enter a decree or
         order (i) for the appointment of a receiver, liquidator, assignee,
         trustee or sequestrator (or other similar official) of the Company or
         any of its Significant Subsidiaries or of any part of the property of
         such Person, or for the winding-up or liquidation of the affairs of
         such Person, and such decree or order shall remain in force and
         undischarged and unstayed for a period of more than thirty (30) days,

         or (ii) for the sequestration or attachment of any property of the
         Company or any of its Significant Subsidiaries without its
         unconditional return to the possession of such Person, or its
         unconditional release from such sequestration or attachment, within
         thirty (30) days thereafter;


                                      -62-

<PAGE>



                            (m) a court having jurisdiction in the premises
         shall enter an order for relief in an involuntary case commenced
         against the Company or any of its Significant Subsidiaries under the
         Federal Bankruptcy Code, and such order shall remain in force
         undischarged and unstayed for a period of more than thirty (30) days;

                            (n) a court or other governmental authority or
         agency having jurisdiction in the premises shall enter a decree or
         order approving or acknowledging as properly filed or commenced against
         the Company or any of its Significant Subsidiaries a petition or
         proceedings for liquidation, rehabilitation, readjustment or
         composition (or for any related or similar purpose) under any law
         (other than the Federal Bankruptcy Code) relating to financially
         distressed debtors, their creditors or property, and any such decree or
         order shall remain in force and undischarged and unstayed for a period
         of more than thirty (30) days; or

                            (o) the Company or any of its Significant
         Subsidiaries shall take corporate action for the purpose or with the
         effect of authorizing, acknowledging or confirming the taking or
         existence of any action or condition specified in paragraph (i), (j) or
         (k) above;

then, in the case of any such Event of Default referred to in clause (i), (j),
(k), (1), (m) or (n) of this Section 18.1, automatically, or, in the case of any
other such Event of Default, at the option of the holder or holders of not less
than twenty-five percent (25%) in aggregate principal amount of the Debentures
at the time Outstanding, exercised by written notice to the Company, the
Debentures, together with the interest accrued thereon, shall forthwith become
and be due and payable, without any other presentment, demand, protest or notice
of any kind, all of which are hereby expressly waived; provided, however, that
in the case of any Event of Default specified in clause (a) or (b) of this
Section 18.1, such option may be exercised by the holder of any Debenture by
written notice to the Company and such Debenture, together with interest accrued
thereon, shall in such case forthwith become and be due and payable, without any
other presentment, demand, protest or notice of any kind, all of which are
hereby expressly waived.

                  18.2. Default Remedies. If an Event of Default exists, the
holder of any Debenture then outstanding may exercise any right, power or remedy
permitted to it by law, either by suit in equity or by action at law or both,

whether for specific performance of any covenant or agreement contained in this
Agreement or in aid of the exercise of any power granted in this Agreement, or
the holder of any Debenture may proceed to enforce payment of such Debenture or
to enforce any other legal or equitable right of the holder of such Debenture.
No course of dealing on the part of any holder of any Debenture or any delay or
failure on the part of any holder of any Debenture to exercise any right shall
operate as a waiver of such right or otherwise prejudice such holder's, or any
other holder's rights, powers and remedies. If an Event of Default exists, the
Company will pay to the holders of the Debentures, to the extent not prohibited
by law, such further amount as shall be sufficient to cover the cost and
expenses of collection or other proceedings, including, but not limited to,
reasonable attorneys' fees.


                                      -63-

<PAGE>



                  18.3. Notice of Default. If any one (1) or more of the Events
of Default specified in Section 18.1 above shall occur, or if the holder of any
Debenture or of any other evidence of Indebtedness of the Company gives any
notice or takes any other action with respect to a claimed default, the Company
will forthwith give written notice thereof to all holders of Debentures then
Outstanding describing the notice or action and the nature of the claimed
default, including any Event of Default.

                  18.4. Annulment of Acceleration of Debentures. If notice is
delivered pursuant to Section 18.1 by any holder or holders of the requisite
principal amount of the Debentures, then and in every such case, the holders of
at least fifty-one percent (51%) in aggregate principal amount of the Debentures
then Outstanding may, by written instrument filed with the Company, rescind and
annul such declaration and the consequences thereof; provided, however, that at
the time such declaration is annulled and rescinded:

                            (a) no judgment or decree has been entered for the
         payment of any monies due pursuant to the Debentures or this Agreement;

                            (b) all arrears of principal and interest upon all
         of the Debentures and all other sums payable under the Debentures and
         under this Agreement (including costs and expenses of the holders
         incurred in connection with such notice under Section 18.1 and the
         exercise of remedies under Section 18.2, but excluding any principal,
         interest or premium on the Debentures which has become due and payable
         by reason of such notice under Section 18.1) shall have been duly paid;
         and

                            (c) each and every other default and Event of
         Default shall have been waived pursuant to Section 22 or otherwise made
         good or cured;

and provided, further, that no such rescission and annulment shall extend to or
affect any subsequent default or Event of Default or impair any right consequent

thereon.

         18.5. Accelerations and other Remedies Limited Prior to Senior Notes
Reduction Date. Notwithstanding anything in Sections 18.1 through Section 18.4
to the contrary, prior to the Senior Notes Reduction Date no holder of any
Debenture shall have the right to accelerate any payments on such Debenture or
exercise any other remedies or rights against the Company, any Guarantor or any
other Subsidiary of the Company arising from any Event of Default as defined
herein except for (i) the Events of Default specified in paragraph (i), (j),
(k), (l), (m) or (n) of Section 18.1, (ii) the Event of Default specified in
paragraph (h) of Section 18.1, provided that the applicable amount of any final
judgments or orders for the payment of money thereunder is at least $50 million,
or (iii) any Event of Default under paragraph (f) or (g) of this Agreement that
results in the acceleration of payment with respect to Indebtedness (other than
the Debentures) in the aggregate principal amount of at least $50 million.


                                      -64-

<PAGE>



         19.      Interpretation of Agreement and Debentures.

                  Acquired Indebtedness: means Indebtedness of a Person existing
at the time such Person becomes a Restricted Subsidiary or assumed in connection
with an Asset Acquisition by a Restricted Subsidiary and not Incurred in
connection with, or in anticipation of, such Person becoming a Restricted
Subsidiary or such Asset Acquisition.

                  Acquirer's Common Stock: the meaning specified in Section
15.13(a).

                  Acquiring Company: the meaning specified in Section 15.13(a).

                  Adjusted Consolidated Net Income: means, for any period, the
aggregate net income (or loss) of the Company and its Restricted Subsidiaries
for such period determined in conformity with GAAP; provided that the following
items shall be excluded in computing Adjusted Consolidated Net Income (without
duplication): (i) the net income of any Person (other than net income (or loss)
attributable to a Restricted Subsidiary) in which any Person (other than the
Company or any of its Restricted Subsidiaries) has a joint interest and the net
income (or loss) of any Unrestricted Subsidiary, except to the extent of the
amount of dividends or other distributions actually paid to the Company or any
of its Restricted Subsidiaries by such other Person or such Unrestricted
Subsidiary during such period; (ii) solely for the purposes of calculating the
amount of Restricted Payments that may be made pursuant to clause (C) of the
first paragraph of Section 13.6 (and in such case, except to the extent
includable pursuant to clause (i) above), the net income (or loss) of any Person
accrued prior to the date it becomes a Restricted Subsidiary or is merged into
or consolidated with the Company or any of its Restricted Subsidiaries or all or
substantially all of the property and assets of such Person are acquired by the
Company or any of its Restricted Subsidiaries; (iii) any gains or losses (on an

after-tax basis) attributable to Asset Sales; (iv) except for purposes of
calculating the amount of Restricted Payments that may be made pursuant to
clause (C) of the first paragraph of Section 13.6, any amount paid or accrued as
dividends on Preferred Stock of the Company or any Restricted Subsidiary owned
by Persons other than the Company and any of its Restricted Subsidiaries; (v)
all extraordinary gains and extraordinary losses; and (vi) any net income (or
loss) of any Guarantor that ceases to be a Guarantor because it is designated an
Unrestricted Subsidiary.

                  Adjusted Consolidated Net Tangible Assets: means the total
amount of assets of the Company and its Restricted Subsidiaries (less applicable
depreciation, amortization and other valuation reserves), except to the extent
resulting from write-ups of capital assets (excluding write-ups in connection
with accounting for acquisitions in conformity with GAAP), after deducting
therefrom (i) all current liabilities of the Company and its Restricted
Subsidiaries (excluding intercompany items) and (ii) all goodwill, trade names,
trademarks, patents, unamortized debt discount and expense and other like
intangibles, all as set forth on the most recent quarterly or annual
consolidated balance sheet of the Company and its Restricted Subsidiaries,
prepared in conformity with GAAP and filed with the Commission.


                                      -65-

<PAGE>



                  Affiliate: means, as applied to any Person, any other Person
directly or indirectly controlling, controlled by, or under direct or indirect
common control with, such Person. For purposes of this definition, "control"
(including, with correlative meanings, the terms "controlling," "controlled by"
and "under common control with"), as applied to any Person, means the
possession, directly or indirectly, of the power to direct or cause the
direction of the management and policies of such Person, whether through the
ownership of voting securities, by contract or otherwise. The term "Affiliate"
when used as a reference to an Affiliate of the Company or any of its
Subsidiaries shall not mean or refer to (i) BAe, BAC, PLC or any of their
Affiliates (exclusive of the Company or its Subsidiaries) or (ii) Matra, the
Lagardere Groupe SCA, MCN Sat US Inc., MCN Sat Service S.A., or any of their
Affiliates (exclusive of the Company or its Subsidiaries).

                  Agreements and Instruments: the meaning specified in Section
5.9.

                  Annual Report: the meaning specified in Section 5.5.

                  Applicable Divisor: means (i) $14 provided that the average of
the Closing Price per share of the Common Stock for the 20 Trading Days (the
"Twenty Day Average") immediately prior to the date as of which the Applicable
Divisor is determined (the "Divisor Date") is greater than $12.80, (ii) the
Twenty Day Average, if $12.80 or less but greater than $10.21 at the Divisor
Date, or (iii) $10.21 if the Twenty Day Average is $10.21 or less, at the
Divisor Date. The initial Applicable Divisor thresholds amounts ($14, $12.80,

$10.21) and any amount to which such thresholds are adjusted, shall be
proportionately decreased in the event that the Company at any time subdivides
(by any stock split, stock dividend, recapitalization or otherwise) the
outstanding shares of Common Stock into a greater number of shares or
proportionately increased in the event that the Company at any time combines (by
reverse stock split, recapitalization or otherwise) the outstanding shares of
Common Stock into a smaller number of shares.

                  Applicable Law: means any Federal, state, local or foreign
statute, law, ordinance, governmental rule or regulation or any judgment,
decree, rule or order of any court or governmental agency or authority
applicable to the Company or any of its Subsidiaries or any of their respective
properties, assets or operations.

                  Article Tenth:  the meaning specified in Section 5.28.

                  Asset Acquisition: means (i) an investment by the Company or
any of its Restricted Subsidiaries in any other Person pursuant to which such
Person shall become a Restricted Subsidiary or shall be merged into or
consolidated with the Company or any of its Restricted Subsidiaries; provided
that such Person's primary business is related, ancillary or complementary to
the businesses of the Company and its Restricted Subsidiaries on the date of
such investment or (ii) an acquisition by the Company or any of its Restricted
Subsidiaries of the property and assets of any Person other than the Company or
any of its Restricted Subsidiaries that constitute substantially all of a
division or line of business of such Person;

                                      -66-

<PAGE>



provided that the property and assets acquired are related, ancillary or
complementary to the businesses of the Company and its Restricted Subsidiaries
on the date of such acquisition.

                  Asset Disposition: means the sale or other disposition by the
Company or any of its Restricted Subsidiaries (other than to the Company or
another Restricted Subsidiary) of (i) all or substantially all of the Capital
Stock of any Restricted Subsidiary of the Company or (ii) all or substantially
all of the assets that constitute a division or line of business of the Company
or any of its Restricted Subsidiaries.

                  Asset Sale: means any sale, transfer or other disposition
(including by way of merger, consolidation or sale-leaseback transaction) in one
transaction or a series of related transactions by the Company or any of its
Restricted Subsidiaries to any Person other than the Company or any of its
Restricted Subsidiaries of (i) all or any of the Capital Stock of any Restricted
Subsidiary, (ii) all or substantially all of the property and assets of an
operating unit or business of the Company or any of its Restricted Subsidiaries
or (iii) any other property and assets of the Company or any of its Restricted
Subsidiaries outside the ordinary course of business of the Company or such
Restricted Subsidiary and, in each case, that is not governed by the provisions

of this Agreement applicable to mergers, consolidations and sales of assets of
the Company; provided that "Asset Sale" shall not include (a) sales or other
dispositions of inventory, receivables and other current assets or (b) sales or
other dispositions of assets for consideration at least equal to the fair market
value of the assets sold or disposed of, provided that the consideration
received would be invested in assets that satisfy clause (B) of Section 13.11.

                  Average Life: means, at any date of determination with respect
to any debt security, the quotient obtained by dividing (i) the sum of the
products of (a) the number of years from such date of determination to the dates
of each successive scheduled principal payment of such debt security and (b) the
amount of such principal payment by (ii) the sum of all such principal payments.

                  BAC: British Aerospace Communications, Inc., a Delaware
corporation.

                  BAC, Ltd.: British Aerospace Communications Limited, a company
organized and existing under the laws of England and Wales.

                  BAe:  British Aerospace Holdings, Inc., a Delaware
corporation.

                  Board of Directors: means the Board of Directors of the
Company or a committee consisting of one or more directors lawfully exercising
the relevant powers of the Board.

                  Board Resolution: means a resolution duly adopted by the Board
of Directors, a copy of which, certified by the Secretary or an Assistant
Secretary of the Company to have been duly adopted by the Board of Directors and
to be in full force and effect on the date of such certification, shall have
been delivered to each holder of Debentures.

                                      -67-

<PAGE>




                  Business Day: means any day other than a Saturday, Sunday or
any other day on which commercial banks are authorized by law to be closed in
New York City or the District of Columbia.

                  Capital Stock: means, with respect to any Person, any and all
shares, interests, participations or other equivalents (however designated,
whether voting or non-voting) in equity of such Person, whether now outstanding
or issued after the Closing Date, including, without limitation, all series and
classes of common stock and Preferred Stock.

                  Capitalized Lease: means, as applied to any Person, any lease
of any property (whether real, personal or mixed) of which the discounted
present value of the rental obligations of such Person as lessee, in conformity
with GAAP, is required to be capitalized on the balance sheet of such Person;
and "Capitalized Lease Obligations" means the discounted present value of the
rental obligations under such lease.


                  Change of Control: occurs when any "Person" (as such term is
used in Sections 13(d) and 14(d) of the Exchange Act), is or becomes the
"beneficial owner" (as defined in Rules 13d-3 and 13d-5 under the Exchange Act,
except that a Person shall be deemed to have beneficial ownership of all shares
that any such Person has the right to acquire, whether such right is exercisable
immediately or only after the passage of time) directly or indirectly, of a
majority in the aggregate of the total voting power of the Voting Stock of the
Company, whether as a result of issuance of securities of the Company, market or
private purchases, any merger, consolidation, liquidation or dissolution of the
Company, or otherwise.

                  Change of Control Period: means the ninety (90) day period
commencing on the date a Change of Control occurs; provided, however, that no
Change of Control Period may commence prior to the Senior Notes Reduction Date.
A Change of Control effected by a Purchaser or any of such Purchaser's
Affiliates shall not commence a Change of Control Period with respect to that
Purchaser and any of such Purchaser's Affiliates for purposes of Section 11.3 of
the Agreement.

                  Closing: the meaning specified in Section 2.

                  Closing Date: the meaning specified in Section 2.

                  Closing Price: means, with respect to each share of Common
Stock or other security, for any day, the reported last sales price regular way
per share or, in case no such reported sale takes place on such day, the average
of the reported closing bid and asked prices regular way, in either case (i) on
the New York Stock Exchange as reported in The Wall Street Journal (or other
similar newspaper) for New York Stock Exchange Composite Transactions or, if the
Common Stock or other security is not listed or admitted to trading on such
Exchange, on the principal (as determined by the Company's Board of Directors)
national securities exchange on which the Common Stock or other security is
listed or admitted to trading or (ii) if not listed or admitted to trading on
any national securities exchange, on the Nasdaq National

                                      -68-

<PAGE>



Market, or, if the Common Stock or other security is not listed or admitted to
trading on any national securities exchange or quoted on the Nasdaq National
Market, the average of the closing bid and asked prices in the over-the-counter
market as furnished by any New York Stock Exchange member firm selected from
time to time by the Company for that purpose. If no such prices are available,
the Closing Price per share of Common Stock shall be the fair value of a share
as determined in good faith by the Board of Directors of the Company.

                  Code: means the Internal Revenue Code of 1986, as amended from
time to time and the rules and regulations promulgated thereunder from time to
time.


                  Commission: means the Securities and Exchange Commission or
any other Federal agency at the time administering the Securities Act.

                  Common Stock: means the Common Stock, $.01 par value per
share, of the Company, any stock into which such Common Stock shall have been
changed or any stock resulting from any capital reorganization or
reclassification of such Common Stock, and all other stock of any class or
classes (however designated) of the Company the holders of which have the right,
without limitation as to amount, either to all or to a share of the balance of
current dividends and liquidating dividends after the payment of dividends and
distributions of any shares entitled to preference.

                  Communications Laws: the meaning specified in Section 5.14.

                  Company: the meaning specified in the first paragraph of the
Agreement.

                  Company Notice:  the meaning specified in Section 11.5(a).

                  Company Notice Expiration Date: the meaning specified in
Section 11.5(a).

                  Consolidated EBITDA: means, for any period, the sum of the
amounts for such period of (i) Adjusted Consolidated Net Income, (ii)
Consolidated Interest Expense, to the extent such amount was deducted in
calculating Adjusted Consolidated Net Income, (iii) income taxes, to the extent
such amount was deducted in calculating Adjusted Consolidated Net Income (other
than income taxes (either positive or negative) attributable to extraordinary
and non-recurring gains or losses or sales of assets), (iv) depreciation
expense, to the extent such amount was deducted in calculating Adjusted
Consolidated Net Income, (v) amortization expense, to the extent such amount was
deducted in calculating Adjusted Consolidated Net Income, and (vi) all other
non-cash items reducing Adjusted Consolidated Net Income (other than items that
will require cash payments and for which an accrual or reserve is, or is
required by GAAP to be, made), less all non-cash items increasing Adjusted
Consolidated Net Income, all as determined on a consolidated basis for the
Company and its Restricted Subsidiaries in conformity with GAAP.


                                      -69-

<PAGE>



                  Consolidated Interest Expense: means, for any period, the
aggregate amount of interest in respect of Indebtedness (including, without
limitation, amortization of original issue discount on any Indebtedness and the
interest portion of any deferred payment obligation, calculated in accordance
with the effective interest method of accounting; all commissions, discounts and
other fees and charges owed with respect to letters of credit and bankers'
acceptance financing; the net costs associated with Interest Rate Agreements;
and in respect of Indebtedness that is Guaranteed or secured by the Company or
any of its Restricted Subsidiaries) and all but the principal component of

rentals in respect of Capitalized Lease Obligations paid, accrued or scheduled
to be paid or to be accrued by the Company and its Restricted Subsidiaries
during such period; excluding, however, any premiums, fees and expenses (and any
amortization thereof) payable in connection with the offering of the Debentures,
all as determined on a consolidated basis (without taking into account
Unrestricted Subsidiaries) in conformity with GAAP.

                  Consolidated Leverage Ratio: means, on any Transaction Date,
the ratio of (i) the aggregate amount of Indebtedness of the Company and its
Restricted Subsidiaries on a consolidated basis outstanding on such Transaction
Date to (ii) the aggregate amount of Consolidated EBITDA for the then most
recent four fiscal quarters for which financial statements of the Company have
been filed with the Commission (such four fiscal quarter period being the "Four
Quarter Period"); provided that (A) pro forma effect shall be given to Asset
Dispositions and Asset Acquisitions (including giving pro forma effect to the
application of proceeds of any Asset Disposition) that occur from the beginning
of the Four Quarter Period through the Transaction Date (the "Reference
Period"), as if they had occurred and such proceeds had been applied on the
first day of such Reference Period; and (B) pro forma effect shall be given to
asset dispositions and asset acquisitions (including giving pro forma effect to
the application of proceeds of any asset disposition) that have been made by any
Person that has become a Restricted Subsidiary or has been merged with or into
the Company or any Restricted Subsidiary during such Reference Period and that
would have constituted Asset Dispositions or Asset Acquisitions had such
transactions occurred when such Person was a Restricted Subsidiary as if such
asset dispositions or asset acquisitions were Asset Dispositions or Asset
Acquisitions that occurred on the first day of such Reference Period; provided
that to the extent that clause (A) or (B) of this sentence requires that pro
forma effect be given to an Asset Acquisition or Asset Disposition, such pro
forma calculation shall be based upon the four full fiscal quarters immediately
preceding the Transaction Date of the Person, or division or line of business of
the Person, that is acquired or disposed of for which financial information is
available.

                  Consolidated Net Worth: means, at any date of determination,
stockholders' equity as set forth on the most recently available quarterly or
annual consolidated balance sheet of the Company and its Restricted Subsidiaries
(which shall be as of a date not more than 90 days prior to the date of such
computation), less any amounts attributable to Disqualified Stock or any equity
security convertible into or exchangeable for Indebtedness, the cost of treasury
stock and the principal amount of any promissory notes receivable from the sale
of the Capital Stock of the Company or any of its Restricted Subsidiaries, each
item to be determined in conformity

                                      -70-

<PAGE>



with GAAP (excluding the effects of foreign currency exchange adjustments under
Financial Accounting Standards Board Statement of Financial Accounting Standards
No. 52).


                  Consummation Date: the meaning specified in Section 15.13(a).

                  Conversion Rate: the meaning specified in Section 15.1.

                  Conversion Shares: the shares of Common Stock to be received
upon conversion of any Debenture as provided in Section 15.

                  Converted Debenture Portion: the meaning specified in Section
11.5(a).

                  Convertible Securities means any stock or other securities of
the Company convertible into or exchangeable for Common Stock.

                  Currency Agreement: means any foreign exchange contract,
currency swap agreement or other similar agreement or arrangement designed to
protect the Company or any of its Restricted Subsidiaries against fluctuations
in currency values to or under which the Company or any of its Restricted
Subsidiaries is a party or a beneficiary on the Closing Date or becomes a party
or a beneficiary thereafter.

                  Debentures:  the meaning specified in Section 1.1.

                  Debenture Payment:  the meaning specified in Section 14.2.

                  Decision Period: the meaning specified in Section 11.5(a).

                  Dilutive Event:  the meaning specified in Section 15.5(1).

                  Disqualified Stock: means any class or series of Capital Stock
of any Person that by its terms or otherwise is (i) required to be redeemed
prior to the Stated Maturity of the Debentures, (ii) redeemable at the option of
the holder of such class or series of Capital Stock at any time prior to the
Stated Maturity of the Debentures or (iii) convertible into or exchangeable for
Capital Stock referred to in clause (i) or (ii) above or Indebtedness having a
scheduled maturity prior to the Stated Maturity of the Debentures; provided,
that any Capital Stock that would not constitute Disqualified Stock but for
provisions thereof giving holders thereof the right to require such Person to
repurchase or redeem such Capital Stock upon the occurrence of a "change of
control" occurring prior to the Stated Maturity of the Debentures shall not
constitute Disqualified Stock if the "change of control" provisions applicable
to such Capital Stock are no more favorable to the holders of such Capital Stock
than the provisions contained in Section 11.3 and such Capital Stock
specifically provides that such Person will not repurchase or redeem any such
stock pursuant to such provision prior to the Company's repurchase of such
Debentures as are required to be repurchased pursuant to Section 11.3.


                                      -71-

<PAGE>



                  Documents: means all documents delivered in connection with

the transactions contemplated by this Agreement, including without limitation,
the Debentures, the Subsidiary Guarantee and the Registration Rights Agreement,
collectively, or each of such documents singularly, and any documents or
instruments contemplated by or executed in connection with any of them or any of
the transactions contemplated hereby or thereby.

                  ERISA: means the Employee Retirement Income Security Act of
1974, as amended from time to time, and the rules and regulations promulgated
thereunder from time to time in effect.

                  ERISA Affiliate: any trade or business (whether or not
incorporated) that is treated as a single employer together with either ONS or
the Company under Section 414 of the Code.

                  Environmental Laws: the meaning specified in Section 5.13

                  Event of Default: the meaning specified in Section 18.1.

                  Exchange Act: the Securities Exchange Act of 1934, as amended,
or any similar Federal statute and the rules and regulations of the Commission
thereunder, all as the same shall be in effect at the time.

                  Exchange Agreement: the Section 351 Exchange Agreement and
Plan Conversion dated as of June 1996, as amended, between and among Orion
Atlantic, ONS, Orion Satellite Corporation, BAC, COM DEV Satellite
Communications Limited, Kingston Communications Limited, Lockheed Martin
Commercial Launch Services, Inc., MCN SAT US, Inc. and Trans- Atlantic
Satellite, Inc., pursuant to which each of the Exchanging Partners (as defined
therein) will transfer their limited partnership interests in Orion Atlantic to
the Company in exchange for shares of Series C Preferred Stock.

                  Excluded Issuance: means the issue or sale of (i) shares of
Common Stock by the Company pursuant to the exercise of Options and Convertible
Securities outstanding immediately prior to the Closing Date at exercise prices
that are greater than or equal to the respective exercise prices in effect as of
the Closing Date (as adjusted pursuant to the terms of such securities to give
effect to stock dividends or stock splits or a combination of shares in
connection with a recapitalization, merger, consolidation or other
reorganization occurring after the Closing Date), (ii) up to an aggregate of one
hundred and fifty thousand (150,000) shares of Common Stock by the Company for
any purpose, (iii) Options to acquire Common Stock by the Company pursuant to a
resolution of, or a stock option plan approved by a resolution of, the Board of
Directors of the Company (or the compensation committee thereof) to the
Company's employees or directors, (iv) shares of Common Stock, Options or
Convertible Securities as part of or in connection with the Financing
Transaction (or shares of Common Stock pursuant to the exercise of such Options
and Convertible Securities), (v) shares of Common Stock by the Company as
payment of interest on, or upon conversion of, the Debentures or (vi) shares of

                                      -72-

<PAGE>




Common Stock by the Company as dividends on, or upon conversion of, the Series C
Preferred Stock.

                  Execution Date: means the date on which the Agreement is
executed by the parties.

                  Expiration Time:  the meaning specified in Section 15.4(6).

                  fair market value: means the price that would be paid in an
arm's-length transaction between an informed and willing seller under no
compulsion to sell and an informed and willing buyer under no compulsion to buy,
as determined in good faith by the Board of Directors, whose determination shall
be conclusive if evidenced by a Board Resolution.

                  Federal Bankruptcy Code:  Title 11, United States Code.

                  Financing Transaction: means offer and sale by the Company of
the Senior Notes in an underwritten public offering registered with the
Commission or in a private placement transaction that results in the Company
receiving cash proceeds in the minimum amount of $225,000,000, after deduction
of all escrowed amounts, underwriting commissions, fees and expenses.

                  FCC: the Federal Communications Commission.

                  Four Quarter Period: the meaning specified in Section 19.1.

                  GAAP: means generally accepted accounting principles in the
United States of America as in effect as of the Closing Date, including, without
limitation, those set forth in the opinions and pronouncements of the Accounting
Principles Board of the American Institute of Certified Public Accountants and
statements and pronouncements of the Financial Accounting Standards Board or in
such other statements by such other entity as approved by a significant segment
of the accounting profession. All ratios and computations contained or referred
to in this Agreement or the Debentures shall be computed in conformity with GAAP
applied on a consistent basis, except that calculations made for purposes of
determining compliance with the terms of the covenants and with other provisions
of this Agreement or the Debentures shall be made without giving effect to (i)
the amortization of any expenses incurred in connection with the offering of the
Debentures and (ii) except as otherwise provided, the amortization of any
amounts required or permitted by Accounting Principles Board Opinion Nos. 16 and
17.

                  Government Securities: means direct obligations of,
obligations fully guaranteed by, or participations in pools consisting solely of
obligations of or obligations guaranteed by, the United States of America for
the payment of which guarantee or obligations the full faith and credit of the
United States of America is pledged and which are not callable or redeemable at
the option of the issuer thereof.


                                      -73-

<PAGE>




                  Governmental Authority:

                  (a)       the government of

                            (i) the United States of America or any State or
                  other political subdivision thereof, or

                            (ii) any jurisdiction in which the Company or any
                  Subsidiary conducts all or any part of its business, or which
                  asserts jurisdiction over any properties of the Company or any
                  Subsidiary, or

                  (b) any entity exercising executive, legislative, judicial,
         regulatory or administrative functions of, or pertaining to, any such
         government.

                  Governmental Licenses: the meaning specified in Section 5.12.

                  Guarantee: means any obligation, contingent or otherwise, of
any Person directly or indirectly guaranteeing any Indebtedness or other
obligation of any other Person and, without limiting the generality of the
foregoing, any obligation, direct or indirect, contingent or otherwise, of such
Person (i) to purchase or pay (or advance or supply funds for the purchase or
payment of) such Indebtedness or other obligation of such other Person (whether
arising by virtue of partnership arrangements, or by agreements to keep-well, to
purchase assets, goods, securities or services, to take-or-pay, or to maintain
financial statement conditions or otherwise) or (ii) entered into for purposes
of assuring in any other manner the obligee of such Indebtedness or other
obligation of the payment thereof or to protect such obligee against loss in
respect thereof (in whole or in part); provided that the term "Guarantee" shall
not include endorsements for collection or deposit in the ordinary course of
business. The term "Guarantee" used as a verb has a corresponding meaning.

                  Guarantors: collectively, means (i) the Subsidiaries of the
Company that execute the Subsidiary Guarantee attached hereto as Exhibit B; and
(ii) any other Person that subsequently Guarantees the Company's obligations
under the Debentures pursuant to Section 12.8 or 13.8; provided that any Person
that becomes an Unrestricted Subsidiary in compliance with Section 13.5 shall
not be included in "Guarantors" after becoming an Unrestricted Subsidiary.

                  Hazardous Materials: the meaning specified in Section 5.13.

                  holder: means with respect to any Debenture, the Person in
whose name such Debenture is registered in the register maintained by the
Company pursuant to Section 16.1.

                  Holder Notice:  the meaning specified in Section 11.5(a).


                                      -74-


<PAGE>



                  HSR Act: means the Hart-Scott-Rodino Antitrust Improvements
Act of 1976, as amended to date.

                  HSR Suspension Period: the meaning specified in Section
11.5(c).

                  Incur: means, with respect to any Indebtedness, to incur,
create, issue, assume, Guarantee or otherwise become liable for or with respect
to, or become responsible for, the payment of, contingently or otherwise, such
Indebtedness, including an "Incurrence" of Indebtedness by reason of a Person
becoming a Restricted Subsidiary of the Company; provided that neither the
accrual of interest nor the accretion of original issue discount shall be
considered an Incurrence of Indebtedness.

                  Indebtedness: means, with respect to any Person at any date of
determination (without duplication), (i) all indebtedness of such Person for
borrowed money, (ii) all obligations of such Person evidenced by bonds,
debentures, notes or other similar instruments, (iii) all obligations of such
Person in respect of letters of credit or other similar instruments (including
reimbursement obligations with respect thereto, but excluding obligations with
respect to letters of credit (including trade letters of credit) securing
obligations (other than obligations described in (i) or (ii) above or (v), (vi)
or (vii) below) entered into in the ordinary course of business of such Person
to the extent such letters of credit are not drawn upon or, if drawn upon, to
the extent such drawing is reimbursed no later than the third Business Day
following receipt by such Person of a demand for reimbursement), (iv) all
obligations of such Person to pay the deferred and unpaid purchase price of
property or services, which purchase price is due more than six months after the
date of placing such property in service or taking delivery and title thereto or
the completion of such services, except Trade Payables, (v) all obligations of
such Person as lessee under Capitalized Leases, (vi) all Indebtedness of other
Persons secured by a Lien on any asset of such Person, whether or not such
Indebtedness is assumed by such Person; provided that the amount of such
Indebtedness shall be the lesser of (A) the fair market value of such asset at
such date of determination and (B) the amount of such Indebtedness, (vii) all
Indebtedness of other Persons Guaranteed by such Person to the extent such
Indebtedness is Guaranteed by such Person and (viii) to the extent not otherwise
included in this definition, obligations under Currency Agreements and Interest
Rate Agreements. The amount of Indebtedness of any Person at any date shall be
the outstanding balance at such date of all unconditional obligations as
described above and, with respect to contingent obligations, the maximum
liability upon the occurrence of the contingency giving rise to the obligation,
provided (A) that the amount outstanding at any time with respect to any
Indebtedness issued with original issue discount is the original issue price of
such Indebtedness, (B) Permitted Customer Advances, Prepayment Supports and any
money borrowed, at the time of the Incurrence of any Indebtedness, in order to
pre-fund the payment of interest on such Indebtedness, shall be deemed not to be
"Indebtedness" and (C) that Indebtedness shall not include any liability for
federal, state, local or other taxes.


                  Insolvency Proceeding:  the meaning specified in Section 14.7.


                                      -75-

<PAGE>



                  Interest Rate Agreement: means any interest rate swap
agreement, interest rate cap agreement or other financial agreement or
arrangement designed to protect the Company or any Restricted Subsidiary against
fluctuations in interest rates in respect of Indebtedness to or under the
Company or any of its Restricted Subsidiaries is a party or a beneficiary on the
date hereof or becomes a party or a beneficiary hereafter, provided that the
notional principal amount thereof does not exceed the principal amount of the
Indebtedness of the Company and its Restricted Subsidiaries that bears interest
at floating rates.

                  Interest Shares: means the shares of Common Stock to be
received by the holders of the Debentures as interest in accordance with the
terms of the Debentures and this Agreement.

                  Investment: in any Person means any direct or indirect
advance, loan or other extension of credit (including, without limitation, by
way of Guarantee or similar arrangement; but excluding advances to customers in
the ordinary course of business that are, in conformity with GAAP, recorded as
accounts receivable on the balance sheet of the Company or its Restricted
Subsidiaries) or capital contribution to (by means of any transfer of cash or
other property to others or any payment for property or services for the account
or use of others), or any purchase or acquisition of Capital Stock, bonds,
notes, debentures or other similar instruments issued by, such Person and shall
include (i) the designation of a Restricted Subsidiary as an Unrestricted
Subsidiary and (ii) the fair market value of the Capital Stock (or any other
Investment), held by the Company or any of its Restricted Subsidiaries, of (or
in) any Person that has ceased to be a Restricted Subsidiary, including without
limitation, by reason of any transaction permitted by clause (iii) of Section
13.7. For purposes of the definition of "Unrestricted Subsidiary" and Section
13.6, (i) "Investment" shall include the fair market value of the assets (net of
liabilities (other than liabilities to the Company or any of its Subsidiaries))
of any Restricted Subsidiary at the time that such Restricted Subsidiary is
designated an Unrestricted Subsidiary, (ii) the fair market value of the assets
(net of liabilities (other than liabilities to the Company or any of its
Subsidiaries)) of any Unrestricted Subsidiary at the time that such Unrestricted
Subsidiary is designated a Restricted Subsidiary shall be considered a reduction
in outstanding Investments and (iii) any property transferred to or from an
Unrestricted Subsidiary shall be valued at its fair market value at the time of
such transfer.

                  Investment Company Act:  the meaning specified in Section
5.23.

                  ITU:  the International Telecommunication Union.

                  Junior Securities:  the meaning specified in Section 14.9.


                  Kingston: means Kingston Communications International Limited,
a company organized and existing under the laws of England and Wales.

                  Lien: means any mortgage, pledge, security interest,
encumbrance, lien or charge of any kind (including, without limitation, any
conditional sale or other title retention agreement or lease in the nature
thereof or any agreement to give any security interest).

                                      -76-

<PAGE>




                  Mandatory Sale:  the meaning specified in Section 11.4.

                  Mandatory Sale Date:  the meaning specified in Section
11.4(a).

                  Mandatory Sale Price: the meaning specified in Section 11.4.

                  Market Price:  the meaning specified in Section 15.5(6).

                  Material: means material in relation to the business,
operations, affairs, financial condition, assets, or properties of the Company,
ONS and the Subsidiaries taken as a whole.

                  Material Adverse Effect: means a material adverse effect on
the properties, business, operations, earnings, assets, liabilities or financial
condition of the Company, ONS and the Subsidiaries, taken as a whole, or on the
ability of the Company, ONS or the Subsidiaries to perform their respective
obligations under this Agreement, the Debentures or any of the other Documents.

                  Matra: Matra Marconi Space UK Limited, a company organized and
existing under the laws of England and Wales.

                  Merger Documents: means (a) the Agreement and Plan of Merger
of Orion Merger Company, Inc. ("SUB") with and into ONS, by and among SUB, ONS
and the Company, and (b) the Certificate of Merger of SUB with and into ONS.

                  Merger Transaction: means the transaction described in the
Registration Statement and the Merger Documents pursuant to which outstanding
shares of the common stock and Preferred Stock of ONS are exchanged for shares
of the Common Stock and Preferred Stock of the Company on a one-for-one basis
and pursuant to which ONS shall become a wholly-owned subsidiary of the Company.

                  Moody's: means Moody's Investors Service, Inc. and its
successors.

                  Morgan:  the meaning specified in Section 4.1.

                  Multiemployer Plan: means any Plan which constitutes a
"multiemployer plan" (as such term is defined in Section 4001(a)(3) of ERISA).


                  Net Cash Proceeds: means, (a) with respect to any Asset Sale,
the proceeds of such Asset Sale in the form of cash or cash equivalents,
including payments in respect of deferred payment obligations (to the extent
corresponding to the principal, but not interest, component thereof) when
received in the form of cash or cash equivalents (except to the extent such
obligations are financed or sold with recourse to the Company or any Restricted
Subsidiary) and proceeds from the conversion of other property received when
converted to cash or cash equivalents, net of (i) brokerage commissions and
other fees and expenses (including fees and

                                      -77-

<PAGE>



expenses of counsel and investment bankers) related to such Asset Sale, (ii)
provisions for all taxes (whether or not such taxes will actually be paid or are
payable) as a result of such Asset Sale without regard to the consolidated
results of operations of the Company and its Restricted Subsidiaries, taken as a
whole, (iii) payments made to repay Indebtedness or any other obligation
outstanding at the time of such Asset Sale that either (A) is secured by a Lien
on the property or assets sold or (B) is required to be paid as a result of such
sale and (iv) appropriate amounts to be provided by the Company or any
Restricted Subsidiary of the Company as a reserve against any liabilities
associated with such Asset Sale, including, without limitation, pension and
other post-employment benefit liabilities, liabilities related to compliance
with Environmental Laws and other environmental matters and liabilities under
any indemnification obligations associated with such Asset Sale, all as
determined in conformity with GAAP and (b) with respect to any issuance or sale
of Capital Stock, the proceeds of such issuance or sale in the form of cash or
cash equivalents, including payments in respect of deferred payment obligations
(to the extent corresponding to the principal, but not interest, component
thereof) when received in the form of cash or cash equivalents (except to the
extent such obligations are financed or sold with recourse to the Company or any
Restricted Subsidiary of the Company) and proceeds from the conversion of other
property received when converted to cash or cash equivalents, net of attorney's
fees, accountants' fees, underwriters' or placement agents' fees, discounts or
commissions and brokerage, consultant and other fees incurred in connection with
such issuance or sale and net of taxes paid or payable as a result thereof.

                  Officers' Certificate: means a certificate signed by the
Chairman of the Board, a Vice Chairman of the Board, the Chief Executive
Officer, the President or a Vice President and by the Chief Financial Officer,
the Treasurer, an Assistant Treasurer, the Secretary or an Assistant Secretary
of the Company. One of the officers signing an Officers' Certificate shall be
the principal executive, financial or accounting officer of the Company.

                  ONS:  Orion Oldco Services, Inc., a Delaware corporation.

                  ONS Common Stock:  the meaning specified in Section 5.2(a).

                  ONS Preferred Stock:  the meaning specified in Section 5.2(a).


                  ONS Series A Preferred Stock: the meaning specified in Section
5.2(a).

                  ONS Series B Preferred Stock: the meaning specified in Section
5.2(a).

                  Options: means any options, warrants or rights to subscribe
for or to purchase Common Stock or any Convertible Securities.

                  Orion Atlantic: International Private Satellite Partners,
L.P., a Delaware limited partnership.


                                      -78-

<PAGE>



                  Orion 1: means the high-power Ku-band communications satellite
operated over the Atlantic Ocean by ONS.

                  Orion 1 Satellite Contract: means the fixed price turnkey
contract originally entered into between PLC and Orion Atlantic for the design,
construction, launch and delivery in orbit of Orion 1.

                  Orion 2 and Orion 3: mean, respectively, each of the first two
satellites with respect to which the Company has a Successful Launch after the
Closing Date, and any replacement for either of such satellites.

                  Orion 2 Satellite Contract: means the spacecraft purchase
agreement between ONS and Matra Marconi Space for construction and launch of
Orion 2.

                  Other Securities: means any stock (other than Common Stock)
and other securities of the Company or any other Person (corporate or otherwise)
which the holders of the Debentures at any time shall be entitled to receive, or
shall have received, upon the conversion of the Debentures, in lieu of or in
addition to Common Stock, or which at any time shall be issuable or shall have
been issued in exchange for or in replacement of Common Stock or Other
Securities pursuant to Section 15.13 or otherwise.

                  Outstanding: means when used with respect to Debentures or
Senior Notes means, as the case may be, as of the date of determination, all
Debentures theretofore delivered under this Agreement, or Senior Notes delivered
under the Senior Indentures, except:

                  (i) Debentures, or Senior Notes, theretofore canceled by the
Company or delivered to the Company for cancellation;

                  (ii) Debentures, or Senior Notes, for the payment or
         redemption of which money in the necessary amount has been set aside
         and segregated in trust by the Company for the holders of such

         Debentures, or Senior Notes, provided that if such Debentures, or
         Senior Notes, are to be redeemed, notice of such redemption has been
         duly given pursuant to this Agreement, or Senior Indentures, as the
         case may be;

                  (iii) Senior Notes owned by the Company or any Affiliate of
         the Company, or BAe, BAC, PLC or any of their Affiliates, or Matra or
         any of its Affiliates; and

                  (iv) Debentures that have been converted in accordance with
Section 15;

provided, however, that in determining whether the holders of the requisite
principal amount of Debentures have given any request, demand, authorization,
direction, notice, consent or waiver hereunder, Debentures owned by the Company
or any other obligor upon the Debentures or any Subsidiary or Affiliate of the
Company or such other obligor shall be disregarded and deemed not to be
Outstanding.

                                      -79-

<PAGE>




                  Outstanding on an As-Converted Basis immediately before the
Dilutive Event: the meaning specified in Section 15.5(1).

                  Payment Blockage Period: the meaning specified in Section
14.3.

                  PBGC: means the Pension Benefit Guaranty Corporation referred
to and defined in ERISA or any successor thereto.

                  Permitted Customer Advances: means obligations of the Company
or any Restricted Subsidiary to repay money received by the Company or such
Restricted Subsidiary from customers as bona fide prepayment for services to be
provided by, or purchases to be made from, the Company or such Restricted
Subsidiary.

                  Permitted Investment: means (i) an Investment in the Company
or a Restricted Subsidiary or a Person which will, upon the making of such
Investment, become a Restricted Subsidiary or be merged or consolidated with or
into or transfer or convey all or substantially all its assets to, the Company
or a Restricted Subsidiary; provided that such person's primary business is
related, ancillary or complementary to the businesses of the Company and its
Restricted Subsidiaries on the date of such Investment; (ii) Temporary Cash
Investments; (iii) payroll, travel and similar advances to cover matters that
are expected at the time of such advances ultimately to be treated as expenses
in accordance with GAAP; and (iv) stock, obligations or securities received in
satisfaction of judgments.

                  Permitted Liens: means (i) Liens for taxes, assessments,

governmental charges or claims that are being contested in good faith by
appropriate legal proceedings promptly instituted and diligently conducted and
for which a reserve or other appropriate provision, if any, as shall be required
in conformity with GAAP shall have been made; (ii) statutory and common law
Liens of landlords and carriers, warehousemen, mechanics, suppliers,
materialmen, repairmen or other similar Liens arising in the ordinary course of
business and with respect to amounts not yet delinquent or being contested in
good faith by appropriate legal proceedings promptly instituted and diligently
conducted and for which a reserve or other appropriate provision, if any, as
shall be required in conformity with GAAP shall have been made; (iii) Liens
incurred or deposits made in the ordinary course of business in connection with
workers' compensation, unemployment insurance and other types of social
security; (iv) Liens incurred or deposits made to secure the performance of
tenders, bids, leases, statutory or regulatory obligations, bankers'
acceptances, surety and appeal bonds, government contracts, performance and
return-of-money bonds and other obligations of a similar nature incurred in the
ordinary course of business (exclusive of obligations for the payment of
borrowed money); (v) easements, rights-of-way, municipal and zoning ordinances
and similar charges, encumbrances, title defects or other irregularities that do
not materially interfere with the ordinary course of business of the Company or
any of its Restricted Subsidiaries; (vi) Liens (including extensions and
renewals thereof) upon real or personal property acquired after the Closing
Date; provided that (a) such Lien is created solely for the purpose of securing
Indebtedness Incurred, in accordance with Section 13.5, (1) to finance the cost
(including the cost of improvement, launch (in the case of

                                      -80-

<PAGE>



property that is a satellite), insurance (in the case of property that is a
satellite), development and design, installation or construction) of the item of
property or assets subject thereto and such Lien is created prior to, at the
time of or within twelve (12) months after the later of the acquisition, the
completion of construction or the commencement of full operation of such
property or (2) to refinance any Indebtedness previously so secured, (b) the
principal amount of the Indebtedness secured by such Lien does not exceed one
hundred percent (100%) of such cost (plus, in the case of any refinancing
Indebtedness referred to in clause (vi)(a)(2) above, premiums, accrued interest,
fees and expenses), (c) any Lien permitted by this clause shall not extend to or
cover any property or assets other than such item of property or assets and any
improvements on such item and (d) such Liens may not relate to Orion 2 or Orion
3; (vii) leases or subleases granted to others that do not materially interfere
with the ordinary course of business of the Company and its Restricted
Subsidiaries, taken as a whole; (viii) Liens encumbering property or assets
under construction arising from progress or partial payments by a customer of
the Company or its Restricted Subsidiaries relating to such property or assets;
(ix) any interest or title of a lessor in the property subject to any
Capitalized Lease or operating lease; (x) Liens arising from filing Uniform
Commercial Code financing statements regarding leases; (xi) Liens on property
of, or on shares of Capital Stock or Indebtedness of, any Person existing at the
time such Person becomes, or becomes a part of, any Restricted Subsidiary;

provided that such Liens do not extend to or cover any property or assets of the
Company or any Restricted Subsidiary other than the property or assets acquired;
(xii) Liens in favor of the Company or any Restricted Subsidiary; (xiii) Liens
arising from the rendering of a final judgment or order against the Company or
any Restricted Subsidiary of the Company that does not give rise to an Event of
Default; (xiv) Liens securing reimbursement obligations with respect to letters
of credit that encumber documents and other property relating to such letters of
credit and the products and proceeds thereof; (xv) Liens in favor of customs and
revenue authorities arising as a matter of law to secure payment of customs
duties in connection with the importation of goods; (xvi) Liens encumbering
customary initial deposits and margin deposits, and other Liens that are within
the general parameters customary in the industry and incurred in the ordinary
course of business, in each case, securing Indebtedness under Interest Rate
Agreements and Currency Agreements and forward contracts, options, future
contracts, futures options or similar agreements or arrangements designed solely
to protect the Company or any of its Restricted Subsidiaries from fluctuations
in interest rates, currencies or the price of commodities; (xvii) Liens arising
out of conditional sale, title retention, consignment or similar arrangements
for the sale of goods entered into by the Company or any of its Restricted
Subsidiaries in the ordinary course of business in accordance with the past
practices of the Company and its Restricted Subsidiaries prior to the Closing
Date; (xviii) Liens on or sales of receivables; (xix) Liens (including Liens
securing Prepayment Supports) on amounts of money or Temporary Cash Investments
that each represent bona fide prepayments of at least $5 million on agreements
for the long-term sale or lease of capacity on any satellite owned by the
Company or a Restricted Subsidiary, but only to the extent that the amount of
money or Temporary Cash Investments subject to any such Lien does not exceed the
amount of such prepayment and reasonable interest thereon; (xx) Liens
encumbering contracts between the Company or any Restricted Subsidiary and any
third party customer relating to the use of a VSAT owned by the Company or any
Restricted Subsidiary but only if, and so long as, the Indebtedness secured by
any such Lien is

                                      -81-

<PAGE>



also secured by a Lien permitted under clause (vi) of this definition
encumbering such VSAT; and (xxi) Liens upon a satellite and components thereof
during the period in which such satellite is being constructed, provided that
(a) such Liens (1) are for the benefit of only the manufacturer of such
satellite or components and (2) secure only the obligation of the Company or any
Restricted Subsidiary to pay the purchase price for such satellite or components
and (b) such Liens are actually released upon, or prior to, the completion of
construction of such satellite and prior to the launch or commencement of full
operations of such satellite.

                  Person: means any individual, partnership, corporation, joint
venture, limited liability company, association, trust, unincorporated
organization, or a government or agency or political subdivision thereof.

                  Plan: means an "employee benefit plan" (as defined in Section

3(3) of ERISA) which is or has been established or maintained, or to which
contributions are or have been made or are required to be made, by the Company,
ONS or any ERISA Affiliate.

                  PLC: British Aerospace Plc, a company organized and existing
under the laws of England and Wales.

                  Potential Event of Default: means an event or condition which,
with notice or lapse of time or both, would become an Event of Default.

                  Preferred Stock: as applied to the Capital Stock of any
corporation, means Capital Stock of any class or classes (however designated)
which is preferred as to the payment of dividends, or as to the distribution of
assets upon any voluntary or involuntary liquidation or dissolution of such
corporation, over shares of Capital Stock of any other class of such
corporation.

                  Prepayment Support: means the reimbursement obligations of the
Company or any Restricted Subsidiary in connection with any fully secured letter
of credit or similar credit support issued by any third party in connection with
the obligations of the Company or such Restricted Subsidiary to repay amounts
received as bona fide prepayments of at least $5 million on agreements for the
long-term sale or lease of capacity on a satellite owned by the Company or a
Restricted Subsidiary.

                  Proceeding: the meaning specified in Section 14.2.

                  Purchased Shares:  the meaning specified in Section 15.4(6).

                  Purchaser: means either BAe or Matra (or any Affiliate of BAe
or Matra substituted as a purchaser of Debentures pursuant to Section 24) and
Purchasers means BAe and Matra or any such Affiliate.

                  PUC: the meaning specified in Section 5.11.

                                      -82-

<PAGE>




                  Redemption Date: means when used with respect to any Debenture
to be redeemed, means the date fixed for such redemption by or pursuant to this
Agreement.

                  Redemption Indebtedness: means Indebtedness of the Company
which is by its terms expressly subordinated in right of payment of the
Debentures and is incurred for the sole purpose of financing the redemption,
repurchase or acquisition of shares of Series A Preferred Stock or Series B
Preferred Stock which were outstanding on the Closing Date and shares of
Preferred Stock pursuant to options that were outstanding on the Closing Date.

                  Redemption Price: when used with respect to any Debenture to

be redeemed, means the price at which it is to be redeemed pursuant to this
Agreement.

                  Reference Period:  the meaning specified in Section 19.1

                  Registration Statement: means the registration statement of
the Company on Form S-4 filed with the Commission in connection with the Merger
Transaction, including the proxy statement and the prospectus contained therein,
all exhibits thereto and all material incorporated by reference therein.

                  Released Indebtedness: means, with respect to any Asset Sale,
Indebtedness (i) which is owed by the Company or any Restricted Subsidiary (the
"Obligors") prior to such Asset Sale, (ii) which is assumed by the purchaser or
any affiliate thereof in connection with such Asset Sale and (iii) with respect
to which the Obligors receive written, unconditional releases from each
creditor, no later than the closing date of such Asset Sale.

                  Reorganization Transaction: the meaning specified in Section
15.13(a).

                  Repayment Event:  the meaning specified in Section 5.9.

                  Repurchase Date:  the meaning specified in Section 11.3(b).

                  Repurchase Price: the meaning specified in Section 11.3(b).

                  Responsible Officer: shall mean the President, Chief Executive
Officer or Chief Financial Officer of the Company.

                  Restricted Payments:  the meaning specified in Section 13.6.

                  Restricted Subsidiary: means any Subsidiary of the Company
other than an Unrestricted Subsidiary.

                  S&P: means Standard & Poor's Ratings Group and its successors.

                  Scheduled Closing Date: the meaning specified in Section
4.14(b).

                                      -83-

<PAGE>




                  Securities Act: means the Securities Act of 1933, as amended,
or any similar Federal statute and the rules and regulations of the Commission
thereunder, all as the same shall be in effect at the time.

                  Senior Indebtedness: means Indebtedness (including, without
limitation the Senior Notes) unless, in the instrument creating or evidencing
the same or pursuant to which the same is outstanding, it is provided that such
obligations are pari passu or junior or subordinate in right of payment to the

Debentures; provided, however, that Senior Indebtedness shall not be deemed to
include (1) any obligation of the Company to any Subsidiary, (2) any liability
for federal, state, local or other taxes owed or owing by the Company, (3) any
accounts payable or other liability to trade creditors arising in the ordinary
course of business (including guarantees thereof or instruments evidencing such
liabilities), (4) any indebtedness, guarantee or obligation of the Company which
is subordinate or junior in any respect to any other indebtedness, guarantee or
obligation of Company (including, without limitation, the Debentures), or (5)
the portion of any Indebtedness issued in violation of this Agreement.

                  Senior Indentures: means the indentures governing the Senior
Notes as originally executed or as amended or supplemented from time to time.

                  Senior Nonmonetary Default: the meaning specified in Section
14.3.

                  Senior Notes: means the Senior Unsecured Overfunded Cash Pay
Notes and the Senior Unsecured Discount Notes.

                  Senior Notes Reduction Date: means the first date after the
Closing on which the aggregate principal amount of Senior Notes Outstanding is
less than $50,000,000.

                  Senior Payment Default: the meaning specified in Section 14.3.

                  Senior Unsecured Discount Notes: means the Senior Discount
Notes due 2007 to be issued under an indenture, to be dated as of the Closing
Date, between the Company, as issuer, each of the Company's Restricted
Subsidiaries, as guarantors, and a trustee.

                  Senior Unsecured Overfunded Cash Pay Notes: means the Senior
Notes due 2007 to be issued under an indenture, to be dated as of the Closing
Date, between the Company, as issuer, each of the Company's Restricted
Subsidiaries, as guarantors, and a trustee.

                  Series A Preferred Stock: means the Company's Series A 8%
Cumulative Redeemable Convertible Preferred Stock, par value $0.01 per share.

                  Series B Preferred Stock: means the Company's Series B 8%
Cumulative Redeemable Convertible Preferred Stock, par value $0.01 per share.

                  Series C Designation: the meaning specified in Section
5.28(a).

                                      -84-

<PAGE>




                  Series C Preferred Stock: means the Series C 6% Cumulative
Redeemable Convertible Preferred Stock of the Company to be issued pursuant to
the Exchange Agreement.


                  Significant Subsidiary: means, at any date of determination,
any Restricted Subsidiary that, together with its Subsidiaries, (i) for the most
recent fiscal year of the Company, accounted for more than ten percent (10%) of
the consolidated revenues of the Company and its Restricted Subsidiaries or (ii)
as of the end of such fiscal year, was the owner of more than ten percent (10%)
of the consolidated assets of the Company and its Restricted Subsidiaries, all
as set forth on the most recently available consolidated financial statements of
the Company for such fiscal year.

                  Solvent: with respect to any Person on a particular date and,
to the extent applicable, after giving effect to the borrowing hereunder on such
date and to any other Indebtedness being incurred on such date (i) the amount of
the "present fair saleable value" of the assets of such Person and each of its
Subsidiaries will, as of such date, exceed the amount of all "liabilities of
such Person and each of its Subsidiaries, contingent or otherwise," as of such
date, as such quoted terms are determined in accordance with applicable federal
and state laws governing determinations of insolvency of debtors, (ii) the
present fair saleable value of the assets of such Person and each of its
Subsidiaries will, as of such date, be greater than the amount that will be
required to pay the liabilities of such Person and each of its Subsidiaries on
its debts as such debts become absolute and matured, (iii) such Person and each
of its Subsidiaries will not have as of such date, an unreasonably small amount
of capital with which to conduct their business, and (iv) such Person and each
of its Subsidiaries will be able to pay their debts as they mature. For purposes
hereof, "debt" means "liability on a claim," and "claim" means any (x) right to
payment, whether or nor such a right is reduced to judgment, liquidated,
unliquidated, fixed, contingent, matured, unmatured, disputed, undisputed,
legal, equitable, secured, or unsecured, or (y) right to an equitable remedy for
breach of performance if such breach gives rise to a right to payment, whether
or not such right to an equitable remedy is reduced to judgment, fixed,
contingent, matured, unmatured, disputed, secured, or unsecured.

                  Stated Maturity: means, (i) with respect to any debt security,
the date specified in such debt security as the fixed date on which the final
installment of principal of such debt security is due and payable and (ii) with
respect to any scheduled installment of principal of or interest on any debt
security, the date specified in such debt security as the fixed date on which
such installment is due and payable.

                  Stock: means any Conversion Shares and any shares of Common
Stock issued subsequent to the conversion of any of the Debentures as a dividend
or other distribution with respect to, or in exchange for or in replacement of,
the Common Stock issued upon such conversion, or resulting from a subdivision of
the outstanding shares of Common Stock issued upon such conversion into a
greater number of shares by reclassification, stock splits or otherwise.

                  Subject Securities:  the meaning specified in Section 5.28(a).

                                      -85-

<PAGE>



                  Subsidiary: means, with respect to any Person, any
corporation, association or other business entity of which more than fifty
percent (50%) of the voting power of the outstanding Voting Stock is owned,
directly or indirectly, by such Person or one (1) or more other Subsidiaries of
such Person. In addition, for purposes of this Agreement, the term "Subsidiary"
shall also mean and include Orion Atlantic.

                  Subsidiary Guarantee: means the Guarantee substantially in the
form of Exhibit B to be executed by each of the Guarantors.

                  Successful Launch: means with respect to any satellite, the
placing into orbit of such satellite in its assigned orbital position with at
least forty percent (40%) of its transponder capacity fully operational.

                  Temporary Cash Investment: means any of the following: (i)
direct obligations of the United States of America or any agency thereof or
obligations fully and unconditionally guaranteed by the United States of America
or any agency thereof, (ii) time deposit accounts, certificates of deposit and
money market deposits maturing within one hundred and eighty (180) days of the
date of acquisition thereof issued by a bank or trust company which is organized
under the laws of the United States of America, any state thereof or any foreign
country recognized by the United States, and which bank or trust company has
capital, surplus and undivided profits aggregating in excess of $50 million (or
the foreign currency equivalent thereof) and has outstanding debt which is rated
"A" (or such similar equivalent rating) or higher by at least one nationally
recognized statistical rating organization (as defined in Rule 436 under the
Securities Act) or any money-market fund sponsored by a registered broker dealer
or mutual fund distributor, (iii) repurchase obligations with a term of not more
than thirty (30) days for underlying securities of the types described in clause
(i) above entered into with a bank meeting the qualifications described in
clause (ii) above, (iv) commercial paper, maturing not more than ninety (90)
days after the date of acquisition, issued by a corporation (other than an
Affiliate of the Company) organized and in existence under the laws of the
United States of America, any state thereof or any foreign country recognized by
the United States of America with a rating at the time as of which any
investment therein is made of "P-1" (or higher) according to Moody's or "A-1"
(or higher) according to S&P, and (v) securities with maturities of six (6)
months or less from the date of acquisition issued or fully and unconditionally
guaranteed by any state, commonwealth or territory of the United States of
America, or by any political subdivision or taxing authority thereof, and rated
at least "A" by S&P or Moody's.

                  10-K:     the meaning specified in Section 5.5.

                  10-Q:     the meaning specified in Section 5.5.

                  this Agreement: means this Debenture Purchase Agreement
(including the annexed Schedule I and Exhibits), as it may from time to time be
amended, supplemented or modified in accordance with its terms.


                                      -86-

<PAGE>




                  Trade Payables: means, with respect to any Person, any
accounts payable or any other indebtedness or monetary obligation to trade
creditors created, assumed or Guaranteed by such Person or any of its
Subsidiaries arising in the ordinary course of business in connection with the
acquisition of goods or services, in each case which is required to be paid
within one year.

                  Trading Days: means (i) if the Common Stock is listed or
admitted for trading on any national securities exchange, days on which such
national securities exchange is open for business or (ii) if the Common Stock is
quoted on the Nasdaq National Market or any similar system of automated
dissemination of quotations of securities prices, days on which trades may be
made on such system or (iii) if the Common Stock is not listed or admitted to
trading on any national securities exchange or quoted on the Nasdaq National
Market or similar system, days on which the Common Stock is traded in the
over-the-counter market and for which a closing bid and a closing asked price
for the Common Stock are available.

                  Transaction Date: means, with respect to the Incurrence of any
Indebtedness by the Company or any of its Restricted Subsidiaries, the date such
Indebtedness is to be Incurred and, with respect to any Restricted Payment, the
date such Restricted Payment is to be made.

                  Trigger Price: shall initially mean $14.00. The Trigger Price
and any adjustment to the Trigger Price shall be proportionately decreased in
the event the Company at any time subdivides (by any stock split, stock
dividend, recapitalization or otherwise) the outstanding shares of Common Stock
into a greater number of shares or proportionately increased in the event that
the Company at any time combines (by reverse stock split, recapitalization or
otherwise) the outstanding shares of Common Stock into a smaller number of
shares.

                  Underlying Shares:  the meaning specified in Section 11.4.

                  Underwriting Agreement:  the meaning specified in Section 4.1.

                  Unrestricted Subsidiary: means (i) any Subsidiary of the
Company that at the time of determination shall be designated an Unrestricted
Subsidiary by the Board of Directors in the manner provided below, (ii) any
Subsidiary of an Unrestricted Subsidiary or (iii) International Technology
Gateway (U.K.) Limited. The Board of Directors may designate any Restricted
Subsidiary (including any newly acquired or newly formed Subsidiary of the
Company) to be an Unrestricted Subsidiary unless such Subsidiary owns any
Capital Stock of, or owns or holds any Lien on any property of, the Company or
any Restricted Subsidiary; provided that (A) any Guarantee by the Company or any
Restricted Subsidiary of any Indebtedness of the Subsidiary being so designated
shall be deemed an "Incurrence" of such Indebtedness and an "Investment" by the
Company or such Restricted Subsidiary (or both, if applicable) at the time of
such designation; (B) either (I) the Subsidiary to be so designated has total
assets of $1,000 or less or (II) if such Subsidiary has assets greater than
$1,000, such designation would be permitted under Section 13.6 and (C) if

applicable, the Incurrence of Indebtedness and the Investment referred to in
clause (A) of this proviso would be permitted under Section 13.5 and Section
13.6.

                                      -87-

<PAGE>



The Board of Directors may designate any Unrestricted Subsidiary to be a
Restricted Subsidiary; provided that immediately after giving effect to such
designation (x) the Company could Incur $1.00 of additional Indebtedness under
the first paragraph of Section 13.5 and (y) no Potential Event of Default or
Event of Default shall have occurred and be continuing. Any such designation by
the Board of Directors shall be evidenced by a Board Resolution giving effect to
such designation and an Officers' Certificate certifying that such designation
complied with the foregoing provisions, copies of which shall be sent to each
holder of Debentures.

                  Vice President: when used with respect to the Company, means
any vice president, whether or not designated by a number or a word or words
added before or after the title "vice president".

                  Voting Stock: means with respect to any Person, Capital Stock
of any class or kind ordinarily having the power to vote for the election of
directors, managers or other voting members of the governing body of such
Person.

                  VSAT: means very small aperture terminal earth stations that
can be installed on rooftops or elsewhere with antennas as small as 0.8 meters
but ranging in sizes up to 3.6 meters in diameter.

                  Wholly Owned: means, with respect to any Subsidiary of any
Person, the ownership of all of the outstanding Capital Stock of such Subsidiary
(other than any director's qualifying shares or Investments by foreign nationals
mandated by applicable law and Common Stock representing not more than 3% of the
voting power of all Common Stock) by such Person or one or more Wholly Owned
Subsidiaries of such Person.

         20. Expenses. Whether or not the transactions contemplated by this
Agreement shall be consummated, the Company will pay all expenses in connection
with such transactions and in connection with any amendments or waivers (whether
or not the same become effective) under or in respect of this Agreement or the
Debentures, including, without limitation: (a) the cost and expenses of
preparing and reproducing this Agreement and the Debentures, of furnishing all
opinions by counsel for the Company (including any opinions requested by your
special counsel as to any legal matter arising hereunder) and all certificates
on behalf of the Company, and of the Company's performance of and compliance
with all agreements and conditions contained herein on its part to be performed
or complied with; (b) the cost of delivering to your principal office, insured
to your satisfaction, the Debentures sold to you hereunder and any Debentures
delivered to you upon any substitution of Debentures or any Conversion Shares or
Interest Shares delivered pursuant hereto or thereto and of your delivering any

Debentures, insured to your satisfaction, upon any substitution or conversion;
(c) the fees, expenses and disbursements of your U.S. special counsel (Coudert
Brothers for BAe and Powell, Goldstein, Frazer & Murphy for Matra) and U.K.
special counsel (Allen & Overy) to BAe in connection with all due diligence and
the documentation and negotiation of the Debentures, this Agreement and the
exhibits hereto and all ancillary documents and in connection with the
completion of this transaction; and (d) the reasonable out-of-pocket expenses
incurred by you in connection with

                                      -88-

<PAGE>



this transaction. The Company also will pay, and will save you and each holder
of any Debentures harmless from, all claims in respect of the fees, if any, of
brokers and finders, other than any broker or finder retained by you or any such
other holder, and any and all liabilities with respect to any taxes (including
interest and penalties) which may be payable in respect of the execution and
delivery of this Agreement and the issue of the Debentures hereunder and any
amendment or waiver under or in respect of this Agreement or the Debentures.

         21. Survival. All express representations and warranties contained in
this Agreement or made in writing by or on behalf of the Company in connection
with the transactions contemplated by this Agreement shall survive the execution
and delivery of this Agreement, any investigation at any time made by you or on
your behalf, the purchase of the Debentures hereunder, any disposition or
payment of the Debentures or any conversion of the Debentures. All statements
contained in any certificate or other instrument delivered by or on behalf of
the Company pursuant to this Agreement or in connection with the transactions
contemplated hereby shall be deemed representations and warranties of the
Company under this Agreement.

         22.      Amendments and Waivers.

                  Prior to the Closing Date, any term of this Agreement may be
amended, and the observance of any term of this Agreement may be waived, only
with the written consent of the Company, ONS, BAe and Matra. From and after the
Closing Date, any term of this Agreement or of the Debentures may be amended,
and the observance of any term of this Agreement or of the Debentures may be
waived (either generally or in a particular instance and either retroactively or
prospectively), only with the written consent of the Company and with the
written consent of the holders of at least sixty-six and two-thirds percent
(66-2/3%) in principal amount of the then Outstanding Debentures; provided,
however, that without the prior written consent of the holders of all the then
Outstanding Debentures, no such amendment or waiver shall (a) extend the fixed
maturity or reduce the principal amount of, or reduce the rate or extend the
time of payment of interest on, or reduce the amount or extend the time of
payment of any principal or premium (if any) payable (whether as a redemption, a
repurchase or otherwise) on any Debenture, (b) reduce the aforesaid percentage
of the principal amount of the Debentures the holders of which are required to
consent to any such amendment or waiver, or (c) modify any term of Section 14 or
Section 15. Any amendment or waiver effected in accordance with this Section 22

shall be binding upon each holder of any Debenture at the time outstanding, each
future holder of any Debenture and the Company.

         23. Notices. Except as otherwise provided in this Agreement, notices
and other communications under this Agreement shall be in writing and shall be
deemed properly served if (i) mailed by registered or certified mail, return
receipt requested, (ii) delivered by a recognized overnight courier service,
(iii) delivered personally, or (iv) sent by facsimile transmission addressed (a)
if to you, at your address set forth at the beginning of this Agreement, or at
such other address as you shall have furnished to the Company in writing, except
as otherwise provided in Section 17.2 with respect to payments on Debentures
held by you, or (b) if to any other holder of any Debenture, at such address as
such other holder shall

                                      -89-

<PAGE>



have furnished to the Company in writing, or, until any such other holder so
furnishes an address to the Company, then to and at the address of the last
holder of such Debenture who has so furnished an address to the Company, or (c)
if to the Company, at its address set forth at the beginning of this Agreement,
to the attention of the Chief Financial Officer, or at such other address, or to
the attention of such other officer, as the Company shall have furnished to you
and each such other holder in writing. Such notice shall be deemed to have been
received (w) three (3) days after the date of mailing if sent by certified or
registered mail, (x) one (1) day after the date of delivery if sent by overnight
courier, (y) the date of delivery if personally delivered, or (z) the next
succeeding business day after transmission by facsimile.

         24. Substitution of Purchasers; References. (a) Each of BAe and Matra
shall have the right to substitute (in whole or in part) one (1) or more of its
Affiliates as a purchaser of Debentures hereunder, by written notice to the
Company, which notice shall be signed by BAe or Matra, as the case may be, and
each such Affiliate, shall contain each such Affiliate's agreement to be bound
by this Agreement and shall contain a confirmation by each such Affiliate of the
accuracy with respect to it of the representations set forth in Section 6.

         (b) Wherever the word "you" is used in this Agreement, such word shall
be deemed to refer to BAe and Matra and/or any of the Affiliates of BAe or Matra
which is or at any time becomes the holder of any Debenture.

         25. Execution in Counterparts. This Agreement may be executed in any
number of counterparts and by different parties hereto in separate counterparts,
each of which when so executed shall be deemed to be an original and all of
which taken together shall constitute one and the same agreement.

         26. Binding Effect. This Agreement shall be binding upon and inure to
the benefit of the parties hereto and their respective successors and assigns,
except that the Company shall not have the right to assign its rights or
obligations hereunder or any interest herein without your prior written consent
which may be withheld for any reason.


         27. GOVERNING LAW. THIS AGREEMENT AND THE DEBENTURES SHALL BE GOVERNED
BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAW OF THE STATE OF NEW YORK WITHOUT
GIVING EFFECT TO ANY CONFLICT OF LAW PROVISIONS THEREOF.

         28. Consent to Jurisdiction; Appointment of Agent to Accept Service of
Process. (a) The Company irrevocably consents and agrees, for your benefit, that
any legal action, suit or proceeding against it with respect to its obligations,
liabilities or any other matter arising out of or in connection with this
Agreement or any Document or the transaction contemplated hereby or thereby may
be brought in the courts of the State of New York or the courts of the United
States of America located in The City of New York and, until all amounts due and
to become due in respect of this Agreement have been paid, or until any such
legal action, suit or proceeding commenced prior to such payment has been
concluded, hereby irrevocably consents

                                      -90-

<PAGE>



and submits to the non-exclusive jurisdiction of each such court in personam,
generally and unconditionally with respect to any action, suit or proceeding for
itself and in respect of its properties, assets and revenues.

                  (b) The Company appoints and empowers CT Corporation System,
with offices currently at 1633 Broadway, New York, New York 10019, as its
designee, appointee and agent to receive, accept and acknowledge for and on its
behalf, and its properties, assets and revenues, service of any and all legal
process, summons, notices and documents that may be served in any action, suit
or proceeding brought against it in any such United States or State court with
respect to its obligations, liabilities or any other matter arising out of or in
connection with this Agreement or any of the Documents or the transaction
contemplated hereby or thereby and that may be made on such designee, appointee
and agent in accordance with legal procedures prescribed for such courts. If for
any reason such designee, appointee and agent hereunder shall cease to be
available to act as such, the Company agrees to designate a new designee,
appointee and agent in The City of New York on the terms and for the purposes of
this Section 28 satisfactory to you. The Company further hereby irrevocably
consents and agrees to the service of any and all legal process, summons,
notices and documents in any such action, suit or proceeding against it by
serving a copy thereof upon the relevant agent for service of process referred
to in this Section 28 (whether or not the appointment of such agent shall for
any reason prove to be ineffective or such agent shall accept or acknowledge
such service) or by mailing copies thereof by registered or certified air mail,
postage prepaid, to the applicable party at its address specified in or
designated pursuant to this Agreement. The Company agrees that the failure of
any such designee, appointee and agent to give any notice of such service to it
shall not impair or affect in any way the validity of such service or any
judgment rendered in any action or proceeding based thereon. Nothing herein
shall in any way be deemed to limit your ability to serve any such legal
process, summons, notices and documents in any other manner permitted by
applicable law or to obtain jurisdiction over such party or bring actions, suits

or proceedings against such party in such other jurisdictions, and in such
manner, as may be permitted by law, any objection that they may now or hereafter
have to the laying of venue of any of the aforesaid actions, suits or
proceedings arising out of or in connection with this Agreement brought in the
United States Federal courts located in The City of New York or the courts of
the State of New York and hereby further irrevocably and unconditionally waives
and agrees not to plead or claim in any such court that any such action, suit or
proceeding brought in any such court has been brought in an inconvenient forum.

                  (c) The provisions of this Section 28 shall survive any
termination of this Agreement, in whole or in part.

         29. WAIVER OF JURY TRIAL. THE COMPANY HEREBY IRREVOCABLY WAIVES ALL
RIGHT TO A TRIAL BY JURY IN ANY ACTION, PROCEEDING OR COUNTERCLAIM ARISING OUT
OF OR RELATING TO THIS AGREEMENT OR ANY OTHER DOCUMENT OR THE TRANSACTIONS
CONTEMPLATED HEREBY OR THEREBY.


                                      -91-

<PAGE>

         If you are in agreement with the foregoing, please sign the form of
acceptance on the accompanying counterparts of this Agreement and return one (1)
of the same to the Company and ONS, whereupon this Agreement shall become a
binding agreement between you and the Company and ONS.

                                        Very truly yours,

                                        ORION NETWORK SYSTEMS, INC.


                                        By:  /s/ W. Neil Bauer
                                             ------------------------
                                             Name: W. Neil Bauer
                                             Title: President and CEO

                                        ORION OLDCO SERVICES, INC.


                                        By:  /s/ Richard H. Shay
                                             ------------------------
                                             Name: Richard H. Shay
                                             Title: Vice President / Secretary


The foregoing agreement is
hereby accepted as of
the date thereof.

BRITISH AEROSPACE HOLDINGS, INC.


By: /s/ Charles E. Gaba
    ---------------------
    Name: Charles E. Gaba
    Title: Vice President


MATRA MARCONI SPACE
UK LIMITED


By: /s/ J. Gail Bancroft
    ----------------------
    Name: J. Gail Bancroft
    Title: Attorney-in-fact



                                      -92-

<PAGE>

                                   SCHEDULE I

                                                         Principal Amount of
Name and Address of Purchaser                        Debentures to be Purchased

BRITISH AEROSPACE HOLDINGS, INC........................     $ 50,000,000

(1)   All payments on account of the Debentures shall
      be made by wire transfer of immediately
      available funds not later than 11 a.m., New
      York City time, to:


      -----------------------------
      -----------------------------
      -----------------------------

(2)   All notices of such payments and written
      confirmation of such wire transfer shall
      be made to:


      -----------------------------
      -----------------------------
      -----------------------------

(3)   All other communications shall be mailed to:


      ------------------------------
      ------------------------------
      ------------------------------


MATRA MARCONI SPACE UK LIMITED.........................     $ 10,000,000


(1)   All payments on account of the Debentures shall
      be made by wire transfer of immediately
      available funds not later than 11 a.m., New
      York City time, to:


      ------------------------------
      ------------------------------
      ------------------------------


<PAGE>






(2)   All notices of such payments and written
      confirmation of such wire transfer shall
      be made to:


      ------------------------------
      ------------------------------
      ------------------------------

(3)   All other communications shall be mailed to:


      ------------------------------
      ------------------------------
      ------------------------------



                                      -94-

<PAGE>

                                   SCHEDULE II

                           Exceptions to Section 5.11

(a)      Application for conditional authorization of satellite at 12 degrees
         W.L., FCC File No. CSS-91-009-LA - (see FCC Order and Authorization
         released September 25, 1995).

(b)      Application for domestic satellite authorization at 135 degrees W.L.,
         File No. 74-SAT-P/LA-95 (see FCC Memorandum Opinion and order, DA
         96-1938, released November 21, 1996).

(c)      Applications for additional Ku-band facilities at the following orbital
         locations:

                      Orbital Location of
                      Ku-Band Application           FCC File No.

                            127 W.L.                74-SAT-P/LA-95
                            37.5 W.L.               CSS-95-001
                            126 E.L.                CSS-94-009

(d)      Applications for various Ka-band facilities at the following orbital
         locations:

                       Orbital Location of
                       Ka-Band Application          FCC Ref.

                            47 W.L.                 FCC Public Notice, Report
                                                    No. SPB-29
                            93 W.L.                 released November 1, 1995
                            78 E.L.                 DA 95-2273, at pages 4-5
                            83 W.L.
                            126 E.L.
                            127 W.L.

(e)      FCC Report and Order in IB Docket No. 95-41, Regulatory Policies
         Governing Domestic Fixed Satellite and Separate International Satellite
         Systems (DISCO 1), FCC 96-14, released January 22, 1996; petitions for
         reconsideration pending.

(f)      FCC First Report and Order on Interconnection with Local Exchange
         Carriers, 61 Fed. Reg. 45476 (1996) - CC Docket No. 96-98 and CC Docket
         No. 95-185.

(g)      Recommended Decision of Federal-State Joint Board regarding Universal
         Service - FCC Docket No. 96-45.

                                      -95-

<PAGE>

                                                                     EXHIBIT A



               [Form of Convertible Junior Subordinated Debenture]



                           ORION NETWORK SYSTEMS, INC.



THIS DEBENTURE AND THE SHARES OF COMMON STOCK OF ORION NETWORK SYSTEMS, INC. (OR
OTHER SECURITIES) WHICH MAY BE ISSUABLE AS INTEREST HEREON OR UPON ITS
CONVERSION HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED
(THE "SECURITIES ACT"), OR THE SECURITIES LAWS OF ANY OF THE STATES OF THE
UNITED STATES, AND MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR
HYPOTHECATED UNLESS AND UNTIL (I) SUCH SECURITIES HAVE BEEN REGISTERED UNDER THE
SECURITIES ACT, OR (II) THE HOLDER HEREOF PROVIDES (A) A WRITTEN OPINION OF
LEGAL COUNSEL, WHICH COUNSEL AND OPINION (IN FORM AND SUBSTANCE) SHALL BE
REASONABLY SATISFACTORY TO ORION NETWORK SYSTEMS, INC., TO THE EFFECT THAT THE
PROPOSED TRANSFER OF SUCH SECURITIES MAY BE EFFECTED WITHOUT REGISTRATION UNDER
THE SECURITIES ACT, OR (B) A "NO ACTION" LETTER FROM THE SECURITIES AND EXCHANGE
COMMISSION (THE "COMMISSION") REASONABLY SATISFACTORY TO ORION NETWORK SYSTEMS,
INC. TO THE EFFECT THAT UNDER THE SECURITIES ACT THE PROPOSED TRANSFER OF THE
SECURITIES WITHOUT REGISTRATION WILL NOT RESULT IN A RECOMMENDATION BY THE STAFF
OF THE COMMISSION THAT ACTION BE TAKEN WITH RESPECT THERETO, OR (C) SUCH OTHER
EVIDENCE AS MAY BE REASONABLY SATISFACTORY TO ORION NETWORK SYSTEMS, INC. THAT
THE PROPOSED TRANSFER OF SUCH SECURITIES MAY BE EFFECTED WITHOUT REGISTRATION
UNDER THE SECURITIES ACT.





                                      -96-

<PAGE>



         Convertible Junior Subordinated Debenture Due February 1, 2012
(Interest Payable in Common Stock)

No.
$

         ORION NETWORK SYSTEMS, INC., a Delaware corporation formerly known as
Orion Newco Services, Inc. (the "Company"), for value received, hereby promises
to pay to the order of _______________________________________ or registered
assigns, the principal amount of _______________________________
($____________), on February 1, 2012, with interest from the date hereof on the

unpaid balance of such principal amount as provided herein, payable
semi-annually on February 1, and August 1, of each year commencing on August 1,
1997, and at maturity (each an "Interest Payment Date"), until such unpaid
balance shall become due and payable (whether at maturity or at a date fixed for
redemption or repurchase or by declaration or otherwise). Capitalized terms used
and not defined in this Debenture shall have the meanings assigned to them in
the Debenture Purchase Agreement, dated as of January 13, 1997, as amended as of
January 31, 1997 (the "Debenture Purchase Agreement") between and among the
Company, Orion Oldco Services, Inc., formerly known as Orion Network Systems,
Inc. ("ONS"), British Aerospace Holdings, Inc. and Matra Marconi Space UK
Limited.

         Payments of the principal of, and premium, if any, on this Debenture
shall be made in lawful money of the United States of America in immediately
available funds at the principal office of the Company in Rockville, Maryland,
or at such other office or agency in New York County, State of New York, as the
Company shall have designated by written notice to the registered holder of this
Debenture or as otherwise provided in the Debenture Purchase Agreement.

         Payments of interest becoming due and payable on this Debenture shall
be made by issuing to the holder hereof that number of fully paid and
nonassessable shares of Common Stock determined by multiplying the principal
amount of this Debenture by 8.75% per annum (computed on the basis of a 360-day
year of twelve 30-day months) and dividing the resulting product by the
Applicable Divisor and by delivering a certificate or certificates for shares of
such Common Stock in such denomination or denominations as such holder may
request at the address specified by the holder in accordance with the terms of
the Debenture Purchase Agreement.

         This Debenture is one of the Company's Convertible Junior Subordinated
Debentures Due February 1, 2012 (Interest Payable in Common Stock), originally
issued in the aggregate principal amount of $60,000,000 pursuant to the
Debenture Purchase Agreement. The registered holder of this Debenture is
entitled to the benefits of such Debenture Purchase Agreement and may enforce
the agreements of the Company and ONS contained therein and exercise the
remedies provided for thereby or otherwise available in respect thereof and is
subject to the provisions thereof and limitations of rights provided therein.
The Debenture Purchase Agreement contains provisions permitting the amendment or
waiver of certain of the terms thereof.


                                      -97-

<PAGE>



         Payments of the principal of, premium, if any, and interest on this
Debenture are subordinate to and subject in right of payment to the prior
payment in full of certain present and future indebtedness of the Company in the
manner and to the extent provided in the Debenture Purchase Agreement, and the
holder of this Debenture, by his or its acceptance hereof, agrees to be bound by
all of the terms and conditions of such subordination provisions.


         At the option of the holder hereof, this Debenture may, at the times
and upon the conditions set forth in the Debenture Purchase Agreement, be
converted at the principal amount hereof, or any portion thereof, into fully
paid and nonassessable shares of Common Stock (or, under certain circumstances,
other securities as provided in the Debenture Purchase Agreement), as such
shares shall be constituted at the time of conversion at the Conversion Rate in
effect at the time of conversion.

         This Debenture and shares of Common Stock (or other securities) issued
upon the conversion hereof may only be transferred in conformity with applicable
securities laws.

         To the extent provided in the Debenture Purchase Agreement, the Company
agrees to waive any usury defense in respect of any payment of interest on or
with respect to this Debenture.

         As provided in the Debenture Purchase Agreement, upon surrender of this
Debenture for registration of transfer, duly endorsed, or accompanied by a
written instrument of transfer duly executed, by the registered holder hereof or
his attorney duly authorized in writing, a new Debenture for a like principal
amount will be issued to, and registered in the name of, the transferee. Prior
to due presentment for registration of transfer, the Company may treat the
person in whose name this Debenture is registered as the owner hereof for the
purpose of receiving payment and for all other purposes, and the Company shall
not be affected by any notice to the contrary.

         This Debenture is subject to redemption or repurchase in whole or in
part, under certain circumstances as specified in the Debenture Purchase
Agreement.

         In case an Event of Default shall occur and be continuing, the unpaid
balance of the principal of this Debenture, together with any accrued but unpaid
interest hereon, may be declared and become due and payable under the
circumstances, in the manner and with the effect provided in the Debenture
Purchase Agreement. Prior to the Senior Notes Reduction Date, if an Event of
Default shall occur and be continuing, the ability of the holders hereof to
accelerate the unpaid principal of and interest in this Debenture may be limited
as set forth in the Debenture Purchase Agreement.

         Commencing on the Senior Notes Reduction Date, this Debenture is
entitled to the benefits of a Subsidiary Guarantee of the punctual payment when
due of the obligations of the Company under this Debenture and the Debenture
Purchase Agreement in favor of the holders of Debentures. Reference is hereby
made to the Subsidiary Guarantee for a statement of the respective rights,
limitations of rights, duties and obligations under the Subsidiary Guarantee of
the Guarantors and the holders of this Debenture.


                                      -98-

<PAGE>




         THIS DEBENTURE SHALL BE CONSTRUED AND ENFORCED IN ACCORDANCE WITH AND
GOVERNED BY THE INTERNAL LAWS OF THE STATE OF NEW YORK APPLICABLE TO AGREEMENTS
AND INSTRUMENTS EXECUTED AND TO BE PERFORMED ENTIRELY IN SUCH STATE WITHOUT
GIVING EFFECT TO THE CONFLICTS OF LAWS PRINCIPLES THEREOF.

         IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed by the manual or facsimile signature of its authorized officer and its
corporate seal to be affixed or reproduced hereon.




DATED:                                   ORION NETWORK SYSTEMS, INC.


                                         By: ________________________________
                                             Name:
                                             Title:



                                      -99-

<PAGE>


                                                                    EXHIBIT B

                         [Form of Subsidiary Guarantee]




                              SUBSIDIARY GUARANTEE


         This SUBSIDIARY GUARANTEE (the "Guarantee"), dated as of January 31,
1997, is executed and delivered by Orion Satellite Corporation, a Delaware
corporation, Asia Pacific Space and Communications, Ltd., a Delaware
corporation, OrionNet, Inc., a Delaware corporation, Orion Oldco Services, Inc.,
formerly known as Orion Network Systems, Inc., a Delaware corporation, Orion
Atlantic Europe, Inc., a Delaware corporation, Orion Asia Pacific Corporation, a
Delaware corporation, OrionNet Finance Corporation, a Delaware corporation and
International Private Satellite Partners, L.P., a Delaware limited partnership
(collectively, the "Guarantors"), pursuant to the Debenture Purchase Agreement,
dated as of January 13, 1997, as amended as of January 31, 1997 (the "Debenture
Purchase Agreement"), between and among Orion Network Systems, Inc., a Delaware
corporation formerly known as Orion Newco Services, Inc. (the "Issuer"), Orion
Oldco Services, Inc. ("ONS"), British Aerospace Holdings, Inc. and Matra Marconi
Space UK Limited. Capitalized terms used and not defined in this Guarantee shall
have the meanings assigned to them in the Debenture Purchase Agreement.

         WHEREAS, the Issuer has duly authorized the issue and sale of
$60,000,000 in aggregate principal amount of its Convertible Junior Subordinated
Debentures Due February 1, 2012 (Interest Payable in Common Stock) (such
debentures, together with all debentures issued in substitution or exchange
therefor pursuant to the Debenture Purchase Agreement, are herein called the
"Debentures");

         WHEREAS, the Guarantors are Subsidiaries of the Issuer; and

         WHEREAS, the Guarantors, in order to induce persons to purchase and
hold such Debentures, have agreed to enter into this Guarantee and to
unconditionally guaranty the obligations of the Issuer, ONS and any other party
who shall become an obligor under the Debenture Purchase Agreement and the
Debentures (collectively, the "Obligors") to the holders of such Debentures (the
"Holders");

         NOW, THEREFORE, the Guarantors do hereby covenant and agree, as
follows:

         Section 30.       Guarantee.

         30.1. Subject to subsection (b) of this Section 1, each of the
Guarantors, jointly and severally, hereby absolutely, unconditionally and
irrevocably guarantees to each Holder, as if the Guarantors were the principal
debtor, (i) the due and punctual payment and performance of all obligations of

the Obligors under the Debenture Purchase Agreement and the Debentures,
including the obligation to pay the principal of, premium, if any, and interest
on the Debentures,

                                      -100-

<PAGE>



when and as the same shall become due and payable, whether by acceleration,
required repurchase, call for redemption or otherwise (in each case including
interest accruing on or after filing of any petition in bankruptcy or
reorganization relating to the Obligors or any of the Guarantors, whether or not
a claim for post filing interest is allowed in such proceeding), (ii) the
performance of all other obligations of the Obligors to the Holders under the
Debenture Purchase Agreement and the Debentures, all in accordance with the
terms thereof, and (iii) payment of all costs and expenses (including reasonable
fees and out-of-pocket expenses of counsel) arising out of or incurred by the
Holders in connection with the enforcement of this Guarantee or collection of
any amounts due hereunder (such obligations referred to in clauses (i), (ii) and
(iii), above, being referred to herein as the "Obligations"). The Guarantors
hereby further agree that if the Obligors shall fail to pay or perform when due
any of the Obligations, the Guarantors will promptly pay or perform the same.
All payments by the Guarantors hereunder shall be made in U.S. Dollars, in the
same funds as are required to be paid by the Obligors and at the same place as
such payments are required to be made by the Obligors. With respect to any
payments to be made by the Guarantors pursuant to this Guarantee in respect of
any interest due and payable on any Debenture which would otherwise be payable
in shares of Common Stock, such payments shall be made in cash in an amount
determined by multiplying the principal amount of such Debenture by 8.75% per
annum (computed on the basis of a 360-day year of twelve 30-day months),
dividing the resulting product by the Applicable Divisor and by multiplying the
resulting number by the Closing Price per share of the Common Stock on the day
such interest first becomes due and payable. This is a guaranty of payment and
performance, not collection.

         30.2. Notwithstanding anything to the contrary contained in this
Guarantee, the Guarantors shall have no obligations hereunder until the Senior
Notes Reduction Date.

         Section 31. Continuing Guarantee. This Guarantee and all covenants and
agreements of the Guarantors contained herein shall continue in full force and
effect and shall not be discharged until such time as all the Obligations shall
be paid and performed in full and all the agreements of the Guarantors hereunder
shall have been duly performed. The obligations of the Guarantors under this
Guarantee shall be automatically reinstated if and to the extent that for any
reason any payment to any Holder by or on behalf of the Obligors, in respect of
the Obligations, is rescinded or must otherwise be returned by such Holder,
whether as a result of any proceedings in bankruptcy or reorganization or
otherwise, and the Guarantors agree that they will indemnify each Holder on
demand for all reasonable costs and expenses (including reasonable fees and
out-of-pocket expenses of counsel) incurred by such Holder in connection with
its compliance with or reasonable resistance (if requested by the Guarantors) to

any such rescission or restoration. Notwithstanding the generality of the
foregoing, if the Debenture Purchase Agreement or the Debentures shall be
terminated as a result of the rejection or disaffirmance thereof by any trustee,
receiver, liquidator, agent or other representative of the Obligors or any of
their respective properties in any assignment for the benefit of creditors or in
any bankruptcy, insolvency, dissolution or similar proceeding, or the exercise
of any of the rights or remedies under the Debenture Purchase Agreement or the
Debentures is stayed, enjoined or prohibited in any such assignment or
proceeding, the obligations of the Guarantors hereunder shall continue to the
same extent as if the Debenture Purchase Agreement or the Debentures had not
been so rejected or disaffirmed and as if such exercise had not been so stayed,
enjoined and prohibited. The Guarantors shall and do hereby waive all rights and

                                      -101-

<PAGE>



benefits that might accrue to them by reason of any such assignment or
proceeding, and the Guarantors agree that they shall be liable for the full
amount of the Obligations, irrespective of and without regard to any
modification, limitation or discharge of liability of the Obligors that may
result from or in connection with any such assignment or proceeding.

         Section 32. Nature of the Guarantors' Obligations. Each of the
Guarantors guarantees that the Obligations will be paid and performed strictly
in accordance with the terms of the Debenture Purchase Agreement and the
Debentures, regardless of any law, regulation or order now or hereafter in
effect in any jurisdiction affecting any of such terms or the rights of the
Holders with respect thereto. The liability of the Guarantors under this
Guarantee shall be joint and several and shall not be subject to any
counterclaim, setoff, deduction, release, recoupment or defense and shall remain
in full force and effect and shall be irrevocable, absolute and unconditional,
irrespective of any lack of value, genuineness, validity, legality, regularity
or enforceability of the Debenture Purchase Agreement or the Debentures, or any
part of the Obligations or any agreement or instrument relating to the
Obligations, or any substitution, release or exchange of any other guarantee of
or security for any of the Obligations, and, to the fullest extent permitted by
applicable laws, irrespective of any other circumstances whatsoever that might
otherwise constitute a legal or equitable discharge or defense of a surety or
guarantor, it being the intent of this Guarantee that the obligations of the
Guarantors hereunder shall be absolute and unconditional under any and all
circumstances. Without limiting the generality of the foregoing, it is agreed
that the occurrence or existence of any one or more of the following shall not,
to the fullest extent permitted by applicable laws, affect the liability of the
Guarantors hereunder:

                  (a) if at any time or from time to time, without notice to the
Guarantors, the time, manner or place for any performance of or compliance with
any of the Obligations shall be extended, or such performance or compliance
shall be waived;

                  (b) any of the acts mentioned in any of the provisions of the

Debenture Purchase Agreement or the Debentures shall be done or omitted;

                  (c) any of the Obligations shall be modified, supplemented,
amended or compromised in any respect, or any right under the Debenture Purchase
Agreement or the Debentures shall be waived in whole or in part or otherwise
dealt with;

                  (d) the partial payment or performance of the Obligations,
whether as a result of the exercise of any right, remedy, power or privilege or
otherwise, shall be accepted or received (except to the extent of such partial
payment or performance);

                  (e) all or any part of the Obligations shall be settled,
compromised, released, liquidated or enforced upon such terms and in such manner
as any Holder may determine or as applicable laws may dictate;

                  (f) any modification, renewal or amendment of the Debenture
Purchase Agreement or the Debentures or any agreement, approval, consent or
other instrument with respect to any Obligation in any respect;


                                      -102-

<PAGE>



                  (g) any merger or consolidation of, sale of substantial assets
by or other restructuring or termination of the corporate existence of the
Obligors into or with any other Person, or any consent thereto;

                  (h) any change in the ownership of any of the shares of
capital stock of the Obligors;

                  (i) any regulatory change or other governmental action;

                  (j) any legal disability, incapacity or other similar defense
of the Obligors with respect to the Obligations (other than payment and
performance);

                  (k) the cessation, for any cause whatsoever, of the liability
of the Obligors (other than by reason of the full and final payment and
performance of all Obligations);

                  (l) the execution, delivery or performance of the Debenture
Purchase Agreement or the Debentures being invalid or in excess of the powers of
the Obligors or of any Person purporting to act on the Obligors' behalf;

                  (m) any transfer or assignment of the rights of the Obligors
pursuant to the Debenture Purchase Agreement or the Debentures or any other
agreements, documents or instruments relating to the transactions contemplated
thereby;

                  (n) any bankruptcy, insolvency, reorganization, arrangement,

readjustment, composition, liquidation or similar proceeding with respect to the
Obligors or any of their respective properties, or any action taken by any
trustee or receiver or by any court in any such proceeding; or

                  (o) any pursuit of or failure by the Holders to pursue
remedies against the Obligors for the Obligations.

         Section 33. Waiver. The Guarantors hereby waive expressly and
unconditionally (a) acceptance of this Guarantee and proof of reliance by any
Holder hereon, (b) notice of any of the matters referred to above, (c) all
notices that may be required by statute, rule of law or otherwise, now or
hereinafter in effect, to preserve intact any right against the Guarantors,
including, without limitation, any demand for payment or performance, diligence,
presentment, protest and dishonor, proof of notice of nonpayment under the
Debenture Purchase Agreement or the Debentures, and notice of default or notice
of any failure on the part of the Obligors to perform and comply with any
covenant, agreement, term or condition of the Debenture Purchase Agreement or
the Debentures, (d) any requirement of any Holder to take any action whatsoever
to exhaust any remedies under the Debenture Purchase Agreement or the Debentures
and (e) any other circumstance whatsoever that might otherwise constitute a
legal or equitable discharge, release or defense of a guarantor or surety, or
that might otherwise limit recourse against the Guarantors.

         Section 34. Waiver of Subrogation. The Guarantors irrevocably waive,
disclaim and relinquish any claim or other rights which they may now or
hereafter acquire against the

                                      -103-

<PAGE>



Obligors by virtue of having executed this Guarantee or otherwise, including,
without limitation, any right of subrogation, reimbursement, exoneration,
contribution, indemnification, any right to participate in any claim or remedy
of the Holders against the Obligors or any collateral which any such Holder
hereafter acquires, whether or not such claim, remedy or right arises in equity,
or under contract, statute or common law, including, without limitation, the
right to take or receive from the Obligors, directly or indirectly, in cash or
other property or by set-off or in any other manner, payment or security on
account of such claim or other rights until such time as the Obligations shall
have been indefeasibly paid in full. If any amount shall be paid to the
Guarantors in violation of the preceding sentence and the Obligations shall not
have been paid in full, such amount shall be deemed to have been paid to the
Guarantors for the benefit of, and held in trust for the benefit of, the
Holders, and shall forthwith be paid to the Holders.

         Section 35. Waiver of Usury Defense. To the extent provided in Section
12.11 of the Debenture Purchase Agreement, the Guarantors agree to waive any
usury defense in respect of any payment of interest on or with respect to any
Debentures.

         Section 36. Rights to Setoff. In addition to all rights to setoff

against the moneys, securities or other property of the Guarantors given to the
Holders by law, each Holder shall have a right of setoff on account of amounts
due by the Guarantors to such Holder against all moneys, securities and other
property of the Guarantors now or hereafter in the possession of or on deposit
with such Holder, whether held in a general or special account or deposit, or
for safekeeping or otherwise; and every such right of setoff may be exercised
without demand upon or notice to the Guarantors, except that any Holder
exercising such right of setoff shall promptly after the exercise thereof give
notice thereof to the Guarantors. No right of setoff shall be deemed to have
been waived by any act or conduct on the part of any Holder or by any neglect to
exercise such right of setoff, or by any delay in so doing; and every right of
setoff shall continue in full force and effect until specifically waived or
released by an instrument in writing executed by each Holder.

         Section 37. Covenants. Each of the Guarantors hereby agrees and
covenants as follows:

                  (a) at its expense to promptly and duly complete and deliver
to any Holder that may request the same complete copies of such information and
certificates concerning the Guarantors as may be required to enable such Holder
to make any filings which from time to time may be required under any applicable
laws in respect of the Debenture Purchase Agreement or the Debentures, in each
case in such form as such Holder shall furnish to the Guarantors with such
request;

                  (b) at its expense to promptly and duly execute and deliver to
each Holder such further documents and assurances and to take such further
action as any Holder may from time to time reasonably request in order to more
effectively carry out the intent and purpose of this Guarantee and to establish
and protect the rights and remedies created or intended to be created in favor
of the Holders hereunder; and

                  (c) the Guarantors assume the responsibility for being and
keeping informed of the financial condition of the Obligors and of all other
circumstances bearing upon the risk

                                      -104-

<PAGE>



of nonpayment of the Obligations which diligent inquiry would reveal, and agree
that no Holder shall have the duty to advise the Guarantors of information known
to it regarding such condition or any such circumstances.

         Section 38. Representations. Each of the Guarantors hereby represents
and warrants to each Holder as follows:

                  (a) it is a corporation or limited partnership duly organized,
validly existing and in good standing under the laws of the jurisdiction of its
organization, and has the corporate or partnership power and authority to enter
into and perform its obligations under this Guarantee;


                  (b) the execution, delivery and performance of this Guarantee
have been duly authorized by all necessary corporate or partnership action on
the part of the Guarantor, do not require any approval of stockholders or
partners, as the case may be, or approval or consent of any trustee or holders
of any indebtedness or obligations of the Guarantor except such as have been
duly obtained, and none of the execution, delivery or performance hereof
contravenes any applicable laws applicable to or binding on the Guarantor or the
charter documents of the Guarantor or contravenes the provisions of, or
constitutes a default under, or results in the creation of any Lien upon the
property of the Guarantor under, any indenture, mortgage, contract or other
agreement to which the Guarantor is a party or by which it or its properties may
be bound or affected;

                  (c) there is no suit, claim, action, proceeding or
investigation pending or, to the knowledge of the Guarantor, threatened against
or affecting the Guarantor in any court or before any Governmental Authority
which relates to the Debenture Purchase Agreement, the Debentures or this
Guarantee, or which, considering the likelihood of an unfavorable outcome, would
have a Material Adverse Effect on the financial condition or operations of the
Guarantor;

                  (d) no order, license, consent, authorization or approval of,
or exemption by, or the giving of notice to, or the registration with or the
taking of any other action in respect of, any Governmental Authority, and no
filing, recording or registration in any public office or any other place, is
required on behalf of the Guarantor to authorize the execution, delivery and
performance of this Guarantee, except as has been duly obtained or effected; and

                  (e) this Guarantee has been duly authorized by all necessary
corporate or partnership action on the part of the Guarantor and has been duly
executed and delivered by the Guarantor. This Guarantee constitutes the legal,
valid and binding obligation of the Guarantor, enforceable against the Guarantor
in accordance with its terms except as such enforceability may be limited by
bankruptcy, insolvency and other similar laws of general application affecting
the rights of creditors and by general equitable principles.

         Section 39. Assignment. This Guarantee shall be binding upon the
Guarantors and their permitted successors and assigns and shall inure to the
benefit of and be enforceable by the Holders and their respective permitted
successors and assigns. Each Holder and its permitted successors and assigns may
assign this Guarantee or any of its rights and powers hereunder (but only to any
Person to whom its respective rights under the Debenture Purchase Agreement and

                                      -105-

<PAGE>



the Debentures are assigned as permitted by the terms thereof), and in such
event the assignee shall have the same rights and remedies as if originally
named herein in place of such Holder. The Guarantors may not assign this
Guarantee or any of their rights or powers hereunder without the prior written
consent of the Holders and may not transfer their assets substantially as an

entirety to one or more entities without having first made provisions for such
entity or entities becoming a co-obligor of the Guarantors' obligations under
this Guarantee pursuant to an instrument in form and substance reasonably
acceptable to the Holders.

         Section 40. Rights to Deal with the Obligors. At any time and from time
to time, without terminating, affecting or impairing the validity of this
Guarantee or the obligations of the Guarantors hereunder, any Holder may deal
with the Obligors in the same manner and as fully as if this Guarantee did not
exist and shall be entitled, among other things, to grant the Obligors such
extension or extensions of time to perform, or to waive any obligation of the
Obligors to perform, any act or acts as may to such Holder be deemed advisable,
and no such waiver or extension shall in any way limit or otherwise affect any
of the Guarantors' obligations hereunder.

         Section 41. Addresses for Notices. All notices, demands or other
communications to be given or delivered under or by reason of the provisions of
this Guarantee shall be given in accordance with the terms of the Debenture
Purchase Agreement, addressed to the Guarantors as follows:

                     c/o      Orion Network Systems, Inc.
                              2440 Research Boulevard, Suite 400
                              Rockville, MD 20850
                              Attention: Chief Financial Officer
                              Fax Number: (301) 258-3360

or at such other address, or to the attention of such other officer, as the
Issuer shall have furnished to the Holders in writing.

         Section 42. No Waiver; Remedies. No failure on the part of the Holders
to exercise, and no delay in exercising, any right hereunder shall operate as a
waiver thereof; nor shall any single or partial exercise of any right hereunder
preclude any other or further exercise thereof or the exercise of any other
right, power or privilege. The remedies herein provided are cumulative and not
exclusive of any remedies provided by law, and the rights of the Holders herein
are supplemental to, and not in lieu of, any rights of the Holders under the
Debenture Purchase Agreement and the Debentures. It is not and shall not be
necessary for the Holders to inquire into the powers of the Obligors or the
officers or agents acting or purporting to act on the Obligors' behalf and any
Obligations made or created in reliance upon the professed exercise of such
powers shall be governed hereunder.

         Section 43. Continuing Guarantee. This Guarantee is a continuing
guaranty and shall remain in full force and effect until payment and performance
in full of the Obligations.

         Section 44. Amendments, Etc. No amendment or waiver of any provision of
this Guarantee nor consent to any departure by the Guarantors therefrom shall in
any event be

                                      -106-

<PAGE>




effective unless the same shall be in writing and signed by Holders of at least
sixty-six and two-thirds percent in principal amount of the then Outstanding
Debentures, and then such waiver or consent shall be effective only in the
specific instance and for the specific purpose for which given.

         Section 45. Governing Law. This Guarantee shall be governed by, and
construed in accordance with, the laws of the State of New York (without giving
effect to any principles of conflicts of law).

         Section 46. Headings. Headings of the sections of this Guarantee are
inserted for convenience of reference only and shall not be deemed to constitute
a part hereof.

         Section 47. Jurisdiction; Service; Etc. Each of the Guarantors
irrevocably consents and agrees that any legal action, suit or proceeding
against it with respect to its obligations, liabilities or any other matter
arising out of or in connection with this Guarantee may be brought in the courts
of the State of New York or the courts of the United States of America located
in The City of New York and, until all amounts due and to become due in respect
of this Guarantee have been paid, or until any such legal action, suit or
proceeding commenced prior to such payment has been concluded, hereby
irrevocably consents and submits to the non-exclusive jurisdiction of each such
court in personam, generally and unconditionally with respect to any action,
suit or proceeding for itself and in respect of its properties, assets and
revenues. Nothing herein shall in any way be deemed to limit any Holder's
ability to serve any such legal process, summons, notices and documents in any
other manner permitted by applicable law or to obtain jurisdiction over such
party or bring actions, suits or proceedings against such party in such other
jurisdictions, and in such manner, as may be permitted by law, any objections
that they may now or hereafter have to the laying of venue of any of the
aforesaid actions, suits or proceedings arising out of or in connection with
this Guarantee brought in the United States Federal courts located in The City
of New York or the courts of the State of New York and hereby further
irrevocably and unconditionally waives and agrees not to plead or claim in any
such court that any such action, suit or proceeding brought in any such court
has been brought in an inconvenient forum. The Guarantors hereby irrevocably
designate and appoint the Issuer as their agent upon whom process may be served
in any action, suit or proceeding against the Guarantors with respect to this
Guarantee or any of the documents referred to herein, it being understood that
such appointment and designation shall become effective without any further
action on the part of the Guarantors or the Obligors. Final judgment against the
Guarantors in any action, suit or proceeding shall conclusively determine the
fact and amount of indebtedness arising from such judgment, a certified copy of
which shall be conclusive evidence of the fact and amount of indebtedness
arising from such judgment.

         Section 48. Severability. Any provision of this Guarantee which is
prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction,
be ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining provisions hereof, and any such prohibition or
unenforceability in any jurisdiction shall not invalidate or render
unenforceable such provision in any other jurisdiction. To the extent permitted

by applicable law, the Guarantors hereby waive any provision of law which
renders any provision of this Guarantee prohibited or unenforceable in any
respect.


                                      -107-

<PAGE>

         Section 49. Entire Agreement. This Guarantee supersedes any prior
agreements and understandings between the Guarantors and the Holders with
respect to the subject matter hereof and is the complete agreement of the
Guarantors and the Holders with respect to the subject matter hereof.

         IN WITNESS WHEREOF, the Guarantors have caused this Guarantee to be
executed in their names and behalf by such duly authorized officers as of the
date first above written.


ORION OLDCO SERVICES, INC.                    ORION SATELLITE CORPORATION


By:    __________________________             By:    __________________________
       Name:                                         Name:
       Title:                                        Title:

ORIONNET, INC.                                ORION ATLANTIC EUROPE, INC.


By:    __________________________             By:    __________________________
       Name:                                         Name:
       Title:                                        Title:

ORION ASIA PACIFIC CORPORATION                ORIONNET FINANCE CORPORATION

By:    __________________________
       Name:                                  By:    __________________________
       Title:                                         Name:
                                                      Title:

ASIA PACIFIC SPACE AND                        INTERNATIONAL PRIVATE
  COMMUNICATIONS, LTD.                           SATELLITE PARTNERS, L.P.


By:    __________________________             By:    ORION SATELLITE
       Name:                                           CORPORATION
       Title:                                        its general partner

                                              By:    __________________________
                                                     Name:
                                                     Title:

                                      -108-

<PAGE>

                                                                      EXHIBIT C




                          REGISTRATION RIGHTS AGREEMENT


         THIS REGISTRATION RIGHTS AGREEMENT (the "Agreement") is made and
entered into as of January 31, 1997, between and among Orion Network Systems,
Inc., formerly known as Orion Newco Services, Inc., a Delaware corporation (the
"Company"), British Aerospace Holdings, Inc., a Delaware corporation ("BAe"),
and Matra Marconi Space UK Limited, a company organized under the laws of
England and Wales ("Matra") (together, the "Purchasers").

         WHEREAS, the Company proposes to issue and sell to the Purchasers
$60,000,000 aggregate principal amount of its Convertible Junior Subordinated
Debentures Due February 1, 2012 (Interest Payable in Common Stock) (the
"Debentures"), pursuant to the terms of a Debenture Purchase Agreement, dated as
of January 13, 1997, as amended as of January 31, 1997 (the "Debenture Purchase
Agreement");

         WHEREAS, as a condition to the Purchasers' obligations under the
Debenture Purchase Agreement, the Company agrees with each of the Purchasers for
their benefit and for the benefit of the holders from time to time of the
Registrable Securities (as defined herein) whose names appear in the register
maintained by the Company's registrar in accordance with the provisions of the
Debenture Purchase Agreement (each of the foregoing a "Holder," and collectively
the "Holders"), to grant to the Purchasers certain registration rights;

         WHEREAS, the purchase of the Debentures under the Debenture Purchase
Agreement and this Agreement are conditioned upon, among other things, the
consummation of the transactions contemplated under the Section 351 Exchange
Agreement and Plan of Conversion, dated as of June, 1996, as amended, and as may
be further amended from time to time (the "Exchange Agreement"), among Orion
Oldco Services, Inc., formerly known as Orion Network Systems, Inc., a Delaware
corporation ("ONS"), International Private Satellite Partners, L.P., a Delaware
limited partnership, Orion Satellite Corporation, a Delaware corporation, and
British Aerospace Communications, Inc. ("BAC"), a Delaware corporation; COM DEV
Satellite Communications Limited, a Canadian corporation ("COM DEV"); Kingston
Communications International Limited, a company incorporated under the laws of
England ("Kingston"); Lockheed Martin Commercial Launch Services, Inc., a
Delaware corporation ("Lockheed Martin"); MCN Sat US, Inc., a Delaware
corporation ("MCN Sat"); and Trans-Atlantic Satellite, Inc., a Delaware
corporation ("TA Sat") (collectively, BAC, COM DEV, Kingston, Lockheed Martin,
MCN Sat and TA Sat are referred to herein as the "Exchanging Partners").

         NOW, THEREFORE, in consideration of the premises, the parties hereby
consent and agree, as follows:


                                      -109-


<PAGE>



         (a)      Definitions.

         As used in this Agreement, the following capitalized defined terms
shall have the following meanings:

         Business Day: any day other than a Saturday or Sunday or day on which
banking institutions in the State of New York are not required to be open.

         Closing Date: the date of closing of the Company's sale of the
Debentures to the Purchasers as contemplated by the Debenture Purchase
Agreement.

         Commission:  the Securities and Exchange Commission.

         Common Stock: the common stock, par value $.01 per share, of the
Company.

         Company: the meaning set forth in the preamble and shall also include
the Company's successors or other parties who succeed to the Company's
obligations hereunder.

         Debentures: the Convertible Junior Subordinated Debentures Due February
1, 2012 (Interest Payable in Common Stock) of the Company.

         Debenture Purchase Agreement: the meaning set forth in the preamble.

         Eligible Series C Securities: the Series C Securities which a holder
thereof is permitted to sell under the terms of the Transfer Restriction
Agreements.

         Exchange Act: the Securities Exchange Act of 1934, as amended from time
to time.

         Exchange Agreement:  the meaning set forth in the preamble.

         Exchanging Partner:  the meaning set forth in the preamble.

         Holder:  any holder of Registrable Securities.

         Initial Shelf Registrable Securities: Registrable Securities, excluding
the shares of Common Stock or other securities issued or issuable upon
conversion of the Debentures.

         Initial Shelf Registration Statement: the Shelf Registration Statement
filed by the Company pursuant to Section 2(a).

         Losses: any losses, claims, damages, liabilities, costs and expenses,
including, but not limited to, reasonable attorney's fees.


         Managing Underwriters: the investment banker or investment bankers and
manager or managers that shall administer an Underwritten Offering of the
securities covered by any registration statement.


                                      -110-

<PAGE>



         Market Value: with respect to a specified date, the aggregate closing
price of such shares of Common Stock on the principal national stock exchange or
automated quotation system upon which the Common Stock is listed or quoted,
averaged over a period of twenty (20) consecutive Business Days prior to such
date. If during this period the Common Stock is not listed on any securities
exchange, quoted on the Nasdaq National Market, or quoted in the
over-the-counter market, the Market Value will be the fair value of the Common
Stock determined by agreement between the Company and the Holders of a majority
of the Registrable Securities. If such parties are unable to reach agreement
within a reasonable period of time, the fair value of the Common Stock shall be
determined by an independent appraiser experienced in valuing such type of
consideration jointly selected by the Company and the Holders of a majority of
the Registrable Securities. The determination of such appraiser shall be final
and binding upon the parties, and the fees and expenses of such appraiser shall
be borne by the Company.

         Other Registrable Stock: shares of Common Stock which the Company is
obligated to register, or include in a registration statement under the
Securities Act, under any Other Registration Rights Agreement.

         Other Registration Rights Agreement: the following agreements entered
into by ONS on or before the date of the Exchange Agreement under which ONS is
obligated to register, or include in a registration statement under the
Securities Act, shares of capital stock of ONS, and amendments and supplements
to any such agreement entered into on or before the date of the Exchange
Agreement, in each case as such agreement will be amended or assigned prior to
the closing under the Exchange Agreement to transfer all of the ONS rights and
obligations under each of such agreements to the Company: (i) the Registration
Rights Agreement dated as of June 17, 1994, among ONS and the Schedule of
Investors set forth therein, as amended (the "Recent PRRAA")); (ii) the
Registration Rights Agreement, dated as of April 29, 1994, between ONS and Space
Systems/Loral, Inc.; and (iii) the Series C Registration Rights Agreement.

         Person: any individual, partnership, corporation, limited liability
company, trust, or unincorporated organization, or a government or agency or
political subdivision thereof.

         Piggyback Registration: the registration by the Company of the Common
Stock (whether for its own account or for the account of others) under the
Securities Act, other than pursuant to a registration statement filed pursuant
to the provisions of Section 2 or Section 3 hereof or a registration of
securities in connection with a business acquisition or combination or an
employee benefit plan.


         Proceeding: any action, suit, proceeding or investigation or written
threat thereof.

         Registrable Securities: regardless of who holds such securities at the
applicable time, (i) the shares of Common Stock of the Company received by BAe
in connection with the purchase by ONS of BAe's interest in Asia Pacific Space
and Communications Ltd.; (ii) the shares of Common Stock or other securities
issued or issuable upon conversion of the Debentures or issued as interest
payments pursuant to the Debenture Purchase Agreement; and (iii) the 86,505
shares of Common Stock issued pursuant to the respective Warrants of ONS dated
as of December 20, 1991, granted to BAC, exercised on December 31, 1996;
provided, however, that such securities shall cease to be Registrable Securities
when a registration statement with respect

                                      -111-

<PAGE>



to the registration of such securities shall have been declared effective under
the Securities Act and such securities shall have been disposed of pursuant to
such registration statement.

         Registration Expenses: any and all expenses incident to the filing and
effectiveness of each registration statement and performance of or compliance by
the Company with this Agreement, including without limitation: (i) all
Commission, stock exchange or National Association of Securities Dealers, Inc.
("NASD") registration and filing fees, (ii) all fees and expenses incurred in
connection with compliance with state securities or Blue Sky laws (including
reasonable fees and disbursements of counsel in connection with Blue Sky
qualification of any of the Registrable Securities and the preparation of a Blue
Sky memorandum and compliance with the rules of the NASD, (iii) all expenses of
any Persons in preparing or assisting in preparing, word processing, printing
and distributing any registration statement, any prospectus, any amendments or
supplements thereto, any underwriting agreements, securities sales agreements,
certificates and other documents relating to the performance of and compliance
with this Agreement, (iv) all fees and expenses incurred in connection with the
listing of any of the Registrable Securities on any securities exchange or the
Nasdaq National Market, (v) the fees and disbursements of counsel for the
Company and of the independent public accountants of the Company, including the
expenses of any special audits or "cold comfort" letters required by or incident
to such performance and compliance, (vi) the reasonable fees and disbursements
of one special counsel representing the Holders of Registrable Securities, such
special counsel to be selected by the Holders of a majority of the Registrable
Securities being registered, (vii) the fees and expenses of a "qualified
independent underwriter" if required by Rule 2720(c) of the rules of the NASD in
connection with the offering of any of the Registrable Securities, (viii) the
fees and expenses of any escrow agent or custodian, and (ix) any fees and
disbursements of any Underwriters customarily paid by issuers or sellers of
securities and the reasonable fees and expenses of any special experts retained
by the Company in connection with any registration statement, but excluding
underwriting discounts and commissions and transfer taxes, if any, relating to

the sale or disposition of Registrable Securities by a Holder.

         Registration Period: a period terminating fifteen (15) years following
the Closing Date.

         Securities Act: the Securities Act of 1933, as amended from time to
time.

         Series C Preferred Stock: the Series C 6% Cumulative Redeemable
Convertible Preferred Stock of the Company.

         Series C Registration Rights Agreement: the Registration Rights
Agreement dated as of January 31, 1997, among the Company and the Exchanging
Partners.

         Series C Securities: the shares of Common Stock or other securities
issued or issuable upon conversion of the Series C Preferred Stock purchased by
the Exchanging Partners pursuant to the Exchange Agreement or issued as
dividends or distributions pursuant to the Certificate of Designations, Rights
and Preferences establishing the terms and relative rights and preferences of
the Series C Preferred Stock.

         Shelf Registration: a registration required to be effected pursuant to
Section 2(a).


                                      -112-

<PAGE>



         Shelf Registration Statement: a "shelf" registration statement of the
Company which covers the registration of Registrable Securities on a Form S-3,
and all amendments and supplements to such registration statement, including
post-effective amendments, in each case including the prospectus contained
therein, all exhibits thereto and all material incorporated by reference
therein; "Shelf Registration Statement" shall include the Initial Shelf
Registration Statement and each Top-up Shelf Registration Statement.

         Top-up Shelf Registration Statement: the meaning set forth in Section
2(b).

         Transfer Restriction Agreement: means (i) each agreement, dated on or
about the Closing Date, between the Company and any Exchanging Partner and (ii)
each subsequent agreement entered into between the Company and any Exchanging
Partner, any affiliate thereof, any transferee of Series C Preferred Stock or
Common Stock into which such Series C Preferred Stock is converted or which is
issued as a dividend on such Series C Preferred Stock or any other party
pursuant to the terms of another Transfer Restriction Agreement, in each case
which provides for restrictions on transfer of the Series C Preferred Stock or
Common Stock into which such Series C Preferred Stock is converted or which is
issued as a dividend on such Series C Preferred Stock.


         Underwriter: each Person who participates as an underwriter of
securities in a registered offering under the Securities Act.

         Underwritten Offering: a sale of Company securities by the Company or a
holder of such securities to an Underwriter or Underwriters for reoffering to
the public.

         (b)      Shelf Registration.

                  2(a) Filing of Initial Shelf Registration Statement. The
Company shall prepare and cause to be filed as soon as practicable after the
date that is one hundred eighty (180) days after the Closing Date (but not later
than fifteen (15) days thereafter), the Initial Shelf Registration Statement
providing for the registration of all of the Initial Shelf Registrable
Securities. The Company shall use all its best efforts to have the Initial Shelf
Registration Statement declared effective by the Commission as soon as
practicable after filing. The Company shall use its best efforts to keep the
Initial Shelf Registration Statement continuously effective for the Registration
Period, or such shorter period which will terminate when all of the Registrable
Securities covered by the Initial Shelf Registration Statement, as amended from
time to time pursuant to Section 2(b), have been sold pursuant to the Initial
Shelf Registration Statement. Notwithstanding the foregoing, except as set forth
below, any Holder who does not provide information reasonably requested by the
Company in connection with the Initial Shelf Registration Statement shall not be
entitled to have its Registrable Securities included in the Initial Shelf
Registration Statement.

                  2(b) Filing of Subsequent Shelf Registration Statements or
Amendments. The Company shall prepare and cause to be filed on or as soon as
practicable after the first anniversary of the Closing Date (but no later than
ten (10) days thereafter) and as soon as practicable after each of the
successive semi-annual interest payment dates provided for in the Debenture
Purchase Agreement (but no later than ten (10) days thereafter) an additional
Shelf

                                      -113-

<PAGE>



Registration Statement or, at the Company's option, a post-effective amendment
to any then- effective Shelf Registration Statement (a "Top-up Shelf
Registration Statement") providing for the registration of all of the
Registrable Securities comprising shares of Common Stock or other securities
issued as interest payments pursuant to the Debenture Purchase Agreement which
have not been registered previously. The Company shall also use all reasonable
efforts to cause to be filed, as soon as practicable each time after receipt of
a written demand from a Holder (but no later than thirty (30) days thereafter),
an additional Shelf Registration Statement or, at the Company's option, a
post-effective amendment to any then-effective Shelf Registration Statement
(also a "Top-up Shelf Registration Statement") providing for the registration of
any and all of the Registrable Securities each Holder demands to be included in
such Top-up Shelf Registration Statement which have not been registered

previously; provided, however, that no such demand shall be effective before the
first anniversary of the Closing Date or after the end of the Registration
Period. The Company shall use its best efforts to have each such Shelf
Registration Statement or post-effective amendment declared effective by the
Commission as soon as practicable after filing. The Company shall use its best
efforts to keep each Top-up Shelf Registration Statement continuously effective
for the Registration Period, or such shorter period which will terminate when
all of the Registrable Securities covered by such Top-up Shelf Registration
Statement, as amended from time to time pursuant to this Section 2(b), have been
sold pursuant to such Top-up Shelf Registration Statement. Notwithstanding the
foregoing, except as set forth below, any Holder who does not provide
information reasonably requested by the Company in connection with the Top-up
Shelf Registration Statement shall not be entitled to have its Registrable
Securities included in the Top-up Shelf Registration Statement.

                  2(c) Effective Registration Statement, Amendments. A Shelf
Registration Statement pursuant to this Section 2 will not be deemed to have
become effective unless it has been declared effective by the Commission;
provided, however that if, after it has been declared effective, the offering of
any Registrable Securities pursuant to such registration statement is interfered
with by any stop order, injunction or other order or requirement of the
Commission or any other governmental agency or court, such registration
statement will be deemed not to have become effective, and the Company shall be
required to continue to use its best efforts to have such registration statement
declared effective. Further, the Company shall, if necessary, supplement or
amend each Shelf Registration Statement, if required by the rules, regulations
or instructions applicable to the registration form used by the Company for such
Shelf Registration Statement or by the Securities Act or by any other rules and
regulations thereunder for shelf registration.

                  2(d) Expenses. The Company shall pay any and all Registration
Expenses incident to the filing of each Shelf Registration Statement or
otherwise incident to the performance of or compliance by the Company with this
Section 2. Each Holder shall pay all underwriting discounts and commissions and
transfer taxes, if any, relating to the sale or disposition of such Holder's
Registrable Securities pursuant to the Shelf Registration Statement.

         (c)      Demand Registration of Underwritten Offerings.

                  3(a) Requests for Underwritten Registration. At any time
following one hundred eighty (180) days after the Closing Date, one or more
Holders may request that the Company effect a registration under the Securities
Act of all or any of their Registrable

                                      -114-

<PAGE>



Securities in an Underwritten Offering; provided, however, that, unless the
requesting Holder is Matra, the requesting Holders must request registration of
Registrable Securities with a Market Value, on the date of such request, of at
least $20 million; and provided, further, that if the requesting Holder is

Matra, Matra must request registration of Registrable Securities with a Market
Value, as of the date of such request, of at least $10 million. Each request for
an Underwritten Offering shall specify the approximate number of shares of
Registrable Securities requested to be registered and the anticipated per share
price range for such offering. Within ten (10) days after receipt of any such
request, the Company will give written notice of such requested demand
registration to all other Holders and, subject to Section 3(b), will include in
any such registration which constitutes an Underwritten Offering satisfying the
requirements of this Section 3(a), all Registrable Securities with respect to
which the Company has received written requests for inclusion therein within
fifteen (15) days after the date the Company's notice is given.

                  3(b) Priority on Underwritten Offering. If the Managing
Underwriters for an Underwritten Offering advise the Company in writing that in
their reasonable opinion the aggregate number of Registrable Securities to be
included in an Underwritten Offering (together with any other shares of Common
Stock which the Company is required to include in such registration) exceeds the
number of shares which can be sold in an orderly manner in such offering within
a price range acceptable to the holders of a majority of the Registrable
Securities and Other Registrable Stock requested to be included in such
registration, the Company will include in such registration (i) first, the
maximum amount of Registrable Securities requested to be included therein, pro
rata among the respective Holders thereof on the basis of the amount of
Registrable Securities requested to be included in such registration by each
such Holder, and (ii) second, the maximum amount of Other Registrable Stock and
any other securities requested to be included therein (including by the Company,
subject to Section 3(e)), pro rata among the Company and the holders of such
Other Registrable Stock and other securities on the basis of the number of
shares requested to be included in such registration by the Company and each
such holder, in each case up to the greatest number of shares of Common Stock
which in the reasonable opinion of such underwriters can be sold in an orderly
manner in the price range of such offering. In no event shall any Other
Registrable Stock or any other securities be included in an Underwritten
Offering under this Section 3 unless all Registrable Securities requested to be
sold in any such offering have been included therein.

                  3(c) Restrictions on Underwritten Offerings. The Company will
not be obligated to effect more than one Underwritten Offering for Holders of
Registrable Securities within any twelve (12) month period, except as provided
in the following sentence, and will not be obligated to effect an Underwritten
Offering for Holders of Registrable Securities at any time before ninety (90)
days after the earlier of (i) the date the previous registration statement
prepared in connection with an Underwritten Offering for Holders of Registrable
Securities ceases to be effective or (ii) the date that all shares registered
thereunder have been sold. The foregoing limitation on Underwritten Offerings
within any twelve (12) month period shall not apply to a single Underwritten
Offering with respect to Registrable Securities of any Holder (other than Matra)
if the Company effected an Underwritten Offering made at Matra's request within
the preceding twelve (12) months or to a single Underwritten Offering requested
by Matra if the Company effected an Underwritten Offering with respect to
Registrable Securities of any other Holder within the preceding twelve (12)
months.

                                      -115-


<PAGE>




                  3(d) Selection of Underwriters. The Holders of a majority of
the Registrable Securities requested to be included in such Underwritten
Offering will have the right to select the Managing Underwriter(s) to administer
the offering; provided, first, that if the Company is successful in obtaining
the services of one or more Underwriters who have been the Managing Underwriters
for an Underwritten Offering of the Company's securities previously, such
Underwriters shall be the Managing Underwriter(s) to administer the offering;
provided, however, that such Managing Underwriter(s) shall be nationally
recognized investment banking firms approved by the Holders, which approval
shall not be unreasonably withheld; and provided, second, that if the Company
participates in the Underwritten Offering under Section 3(e), such Holders shall
obtain the Company's consent with respect to any Managing Underwriter(s) to
administer the offering, which consent shall not be unreasonably withheld.

                  3(e) Inclusion by the Company of its Common Stock in an
Underwritten Offering. If the Managing Underwriters for an Underwritten Offering
advise the Company in writing that in their opinion the aggregate number of
Registrable Securities to be included in an Underwritten Offering (together with
any Other Registrable Stock) is less than the number of shares which can be sold
in an orderly manner in such offering within a price range acceptable to the
holders of a majority of the Registrable Securities and Other Registrable Stock
requested to be included in such registration, the Company may include in such
registration, on its own behalf, up to the greatest number of shares of Common
Stock which in the opinion of such underwriters can be sold (together with the
Registrable Securities and Other Registrable Stock requested to be included in
such registration) in an orderly manner in the price range of such offering.

                  3(f) Participation in Underwritten Registrations.
Notwithstanding any other provision of this Section 3 to the contrary, no Person
may participate in any Underwritten Offering hereunder unless such Person (a)
agrees to sell such Person's securities on the basis provided in the applicable
underwriting arrangements and (b) completes and executes all questionnaires,
powers of attorney, indemnities, underwriting agreements and other documents
required under the terms of such underwriting arrangements; provided, however,
that no Holder of Registrable Securities included in any Underwritten Offering
shall be required to make any representations or warranties to the Company or
the underwriters other than representations and warranties regarding such Holder
and such Holder's intended method of distribution.

                  3(g) Expenses of Underwriting Offering. The Company shall pay
any and all Registration Expenses incident to the filing of each registration
statement or otherwise incident to the performance of or compliance by the
Company with this Section 3. Each Holder shall pay all underwriting discounts
and commissions and transfer taxes, if any, relating to the sale or disposition
of such Holder's Registrable Securities included in the Underwritten Offering.

                  3(h) Relationship to Shelf Registration. The rights and
obligations of the parties hereto under Section 3 shall be in addition to, and

not in lieu of, their respective rights and obligations under Section 2.

         (d)      Piggyback Registration Rights.


                                      -116-

<PAGE>



                  4(a) Requests for Piggyback Registration. If at any time
following the date of this Agreement, the Company proposes to effect a Piggyback
Registration, the Company will give written notice to all Holders of its
intention to effect such a registration and, subject to Section 4(b) and Section
4(c), will include in such registration all Registrable Securities with respect
to which the Company has received written requests for inclusion therein within
fifteen (15) days after the date the Company's notice is given.

                  4(b) Priority on Primary Registrations. If the proposed
Piggyback Registration is an underwritten primary registration on behalf of the
Company, and the Managing Underwriters advise the Company in writing that in
their opinion the number of securities requested to be included in such
registration exceeds the number which can be sold in such offering in an orderly
manner within a price range acceptable to the Company, the Company will include
in such registration (i) first, the securities the Company proposes to sell and
the High Priority Registrable Securities (as defined in the Recent PRRAA), pro
rata among the Company and the holders of such High Priority Registrable
Securities on the basis of the number of shares requested to be included by the
Company and each such holder, (ii) second, any Other Registrable Stock requested
to be included therein, pro rata among the holders of such Other Registrable
Stock on the basis of the number of shares requested to be included in such
registration by each such holder, and (iii) third, the Registrable Securities
requested to be included in such registration, pro rata among the Holders
thereof on the basis of the amount of Registrable Securities requested to be
included by each such Holder, in each case up to the greatest number of shares
of Common Stock which in the reasonable opinion of such underwriters can be sold
in an orderly manner in the price range of such offering.

                  4(c) Priority on Secondary Registrations. If a Piggyback
Registration is an underwritten secondary registration on behalf of holders of
the Company's securities (other than the Registrable Securities), and the
Managing Underwriters advise the Company in writing that in their opinion the
number of securities requested to be included in such registration exceeds the
number which can be sold in such offering without adversely affecting the
marketability of the offering, the Company will include in such registration (A)
if such registration is on behalf of holders of the Eligible Series C
Securities, (i) first, the securities requested to be included in such
registration under the Series C Registration Rights Agreement, and (ii) second,
the Registrable Securities requested to be included in such registration and any
Other Registrable Stock (excluding Eligible Series C Securities) and any other
securities requested to be included therein (including by the Company, subject
to Section 3(e)), pro rata among such Holders and the holders of such Other
Registrable Stock and other securities on the basis of the number of shares

requested to be included in such registration by each such holder, in each case
up to the greatest number of shares of Common Stock which in the reasonable
opinion of such underwriters can be sold in an orderly manner in the price range
of such offering; or (B) if such registration is not on behalf of holders of the
Eligible Series C Securities (i) first, the securities requested to be included
therein by the holders requesting such registration, and (ii) second, the
greatest number of the Registrable Securities, Other Registrable Stock and any
other securities requested to be included therein (including by the Company,
subject to Section 3(e)), pro rata among such Holders and the holders of such
Other Registrable Stock and other securities on the basis of the number of
shares requested to be included in such registration by each such holder, in
each case up to the greatest number of shares of Common Stock which in the
reasonable

                                      -117-

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opinion of such underwriters can be sold in an orderly manner in the price range
of such offering.

                  4(d) Participation in Piggyback Registrations. Notwithstanding
any other provision of this Section 4 to the contrary, no Person may participate
in any Piggyback Registrations hereunder unless such Person (i) agrees to sell
such Person's securities on the basis provided in the applicable underwriting
arrangements and (ii) completes and executes all questionnaires, powers of
attorney, indemnities, underwriting agreements and other documents required
under the terms of such underwriting arrangements; provided, however, that no
Holder of Registrable Securities included in any Piggyback Registration shall be
required to make any representations or warranties to the Company or the
underwriters other than representations and warranties regarding such Holder and
such Holder's intended method of distribution.

                  4(e) Expenses of Piggyback Registration. The Company shall pay
any and all Registration Expenses incident to the filing of each registration
statement or otherwise incident to the performance of or compliance by the
Company with this Section 4. Each Holder shall pay all underwriting discounts
and commissions and transfer taxes, if any, relating to the sale or disposition
of such Holder's Registrable Securities included in the Piggyback Registration.

         (e)      Registration Procedures.

         In connection with the obligations of the Company with respect to a
registration statement pursuant to Section 2, Section 3 or Section 4 hereof, the
Company shall effect or cause to be effected the registration of the Registrable
Securities under the Securities Act to permit the sale of such Registrable
Securities by the Holders in accordance with their intended method or methods of
distribution, and the Company shall:

                  5(a) prepare and file with the Commission a registration
statement with respect to such Registrable Securities and use its best efforts
to cause such registration statement to become effective within the time period

required hereunder (provided that before filing a registration statement or
prospectus or any amendments or supplements thereto, the Company will furnish to
one counsel selected by the holders of 70% of the Registrable Securities
(together with any Other Registrable Stock) covered by such registration
statement copies of all such documents proposed to be filed, which documents
will be subject to the review of such counsel, and the Company will incorporate
in such registration statement the reasonable comments of such counsel not
inconsistent with the Company's disclosure obligations under applicable
securities laws;

                  5(b) prepare and file with the Commission such amendments and
supplements to such registration statement and the prospectus used in connection
therewith as may be necessary to keep such registration statement effective for
the period required hereunder (or if no period is so required, a period of not
less than one hundred eighty (180) days or such shorter period which is
sufficient to complete the distribution of the securities registered under the
registration statement) and comply with the provisions of the Securities Act
with respect to the disposition of all securities covered by such registration
statement during such period in

                                      -118-

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accordance with the intended methods of disposition by the sellers thereof set
forth in such registration statement;

                  5(c) furnish to each seller of Registrable Securities, the
Managing Underwriters, if any, and their respective counsel, not less than five
(5) Business Days prior to the filing thereof with the Commission, such number
of copies of such registration statement, each amendment and supplement thereto,
the prospectus included in such registration statement (including each
preliminary prospectus) and such other documents as such seller may reasonably
request in order to facilitate the disposition of the Registrable Securities
owned by such seller and to use its best efforts to reflect in each such
document, when so filed with the Commission, such comments as the sellers of
Registrable Securities or their counsel shall reasonably propose;

                  5(d) use its best efforts to register or qualify such
Registrable Securities under such other securities or blue sky laws of such
jurisdictions as any seller reasonably requests and do any and all other acts
and things which may be reasonably necessary or advisable to enable such seller
to consummate the disposition in such jurisdictions of the Registrable
Securities owned by such seller (provided that the Company will not be required
to (i) qualify generally to do business in any jurisdiction where it would not
otherwise be required to qualify but for this subparagraph, (ii) subject itself
to taxation in any such jurisdiction or (iii) consent to general service of
process in any such jurisdiction);

                  5(e) notify each seller of such Registrable Securities as
promptly as practicable in any of the following circumstances: (i) at any time
when a prospectus relating thereto is required to be delivered under the

Securities Act, of the happening of any event as a result of which the
prospectus included in such registration statement contains an untrue statement
of a material fact or omits any fact necessary to make the statements therein
not misleading, and, at the request of any such seller, the Company will prepare
a supplement or amendment to such prospectus so that, as thereafter delivered to
the purchasers of such Registrable Securities, such prospectus will not contain
an untrue statement of a material fact or omit to state any fact necessary to
make the statements therein not misleading; (ii) when a registration statement
and any amendment thereto has been filed with the Commission and when the
registration statement or any post-effective amendment thereto has become
effective; (iii) of any request by the Commission for amendment or supplements
to the registration statement or the prospectus included therein or for
additional information; (iv) of the issuance by the Commission of any stop order
suspending the effectiveness of the registration statement or the initiation of
any proceedings for that purpose; and (v) the receipt by the Company of any
notification with respect to the suspension of the qualification of the
securities included therein for sale in any jurisdiction or the initiation of
any proceeding for such purpose;

                  5(f) cause all such Registrable Securities to be listed on
each securities exchange on which similar securities issued by the Company are
then listed and, if not so listed, to be listed on the NASD automated quotation
system and, if listed on the NASD automated quotation system, use its best
efforts to secure designation of all such Registrable Securities covered by such
registration statement as a Nasdaq "national market system security" within the
meaning of Rule 11Aa2-1 of the Exchange Act or, failing that, to secure Nasdaq
authorization for such Registrable Securities and without limiting the
generality of the foregoing, to arrange

                                      -119-

<PAGE>



for at least two market makers to register as such with respect to such
Registrable Securities with the NASD;

                  5(g) provide a transfer agent and registrar for all such
Registrable Securities not later than the effective date of such registration
statement;

                  5(h) if requested, promptly incorporate in any registration
statement or prospectus, if necessary, pursuant to a supplement or
post-effective amendment to such registration statement, such information as the
Managing Underwriters, if any, or the holders of a majority of Registrable
Securities and Other Registrable Securities being registered reasonably request
to have included therein and shall make all required filings of such prospectus
supplement or post-effective amendment as soon as practicable after the Company
is notified of the matters to be incorporated in such prospectus supplement or
post-effective amendment;

                  5(i) enter into such agreements on terms reasonably acceptable
to the Company (including underwriting agreements) in form, scope and substance

as are customary in underwritten offerings, and take all other reasonable
actions necessary to facilitate the registration or the disposition of the
Registrable Securities included in any registration statement;

                  5(j) (i) make reasonably available at reasonable times for
inspection by the Holders of Registrable Securities to be registered thereunder,
any underwriter participating in any disposition pursuant to such registration
statement, and any attorney, accountant or other agent retained by the Holders
or such underwriters, at the office where normally kept during normal business
hours, all financial and other records, pertinent corporation documents and
properties of the Company and its subsidiaries, and cause the Company's
officers, directors and employees to supply all relevant information reasonably
requested by the Holders, or any underwriters, attorney, accountant or other
agent in connection with the registration statement as is customary for similar
due diligence examinations, provided, however, that such persons shall first
agree in writing with the Company that any information that is reasonably and in
good faith designated by the Company in writing as confidential at the time of
delivery of such information shall be kept confidential by such persons; (ii)
obtain opinions of counsel to the Company and updates thereof (which counsel, if
different from counsel to the Company referred to in the Debenture Purchase
Agreement, shall be reasonably satisfactory to the Holders of a majority of the
Registrable Securities to be registered thereunder, the underwriters, if any,
and their respective counsel) addressed to each selling Holder covering such
matters in form, scope and substance as are customary in underwritten offerings;
(iii) obtain "cold comfort" letters (or, in the case of any person that does not
satisfy the conditions for receipt of a "cold comfort" letter specified in
Statement on Auditing Standards No. 72, an "agreed-upon procedures letter") and
updates thereof from the independent certified public accountants of the Company
(and, if necessary, any other independent certified public accountants of any
subsidiary of the Company or of any business acquired by the Company for which
financial statements and financial data are, or are required to be, included in
the registration statement), addressed where reasonably practicable to each
selling Holder of Registrable Securities registered thereunder, and the
underwriters, if any, in customary form and covering matters of the type
customarily covered in "cold comfort" letters in connection with primary
underwritten offerings; and (iv) deliver such documents and certificates as may
be reasonably requested by the holders of a majority of the Registrable
Securities and Other Registrable Securities to be registered and the Managing

                                      -120-

<PAGE>



Underwriters, if any, including those to evidence compliance with Section 5(e).
The foregoing actions set forth in clauses (ii), (iii) and (iv) of this Section
5(j) shall be performed at (A) the effectiveness of such registration statement
and each post-effective amendment thereto and (B) each closing under any
underwriting or similar agreement as and to the extent required thereunder;

                  5(k) otherwise use its best efforts to comply with all
applicable rules and regulations of the Commission;


                  5(l) use its best efforts to cause such Registrable Securities
covered by such registration statement to be registered with or approved by such
other governmental agencies or authorities as may be necessary to enable the
sellers thereof to consummate the disposition of such Registrable Securities;

                  5(m) take all such action as may be necessary so that (i) any
registration statement and any amendment thereto and any prospectus forming part
thereof and any amendment or supplement thereto (and each report or other
document incorporated therein by reference in each case) complies in all
material respects with the Securities Act and the Exchange Act and the
respective rules and regulations thereunder; (ii) any registration statement and
any amendment thereto does not, when it becomes effective, contain an untrue
statement of a material fact or omit to state a material fact required to be
stated therein or necessary to make the statements therein not misleading; and
(iii) any prospectus forming part of any registration statement, and any
amendment or supplement to such prospectus, does not include an untrue statement
of a material fact or omit to state a material fact necessary in order to make
the statements therein, in light of the circumstances under which they were
made, not misleading;

                  5(n) use its best efforts to prevent the issuance, and if
issued to obtain the withdrawal, of any order suspending the effectiveness of
any registration statement at the earliest possible time;

                  5(o) unless any Registrable Securities shall be in book-entry
form, cooperate with the Holders to facilitate the timely preparation and
delivery of certificates representing Registrable Securities to be sold pursuant
to any registration statement free of any restrictive legend and in such
permitted denominations and registered in such names as the Holders may request
in connection with the sale of Registrable Securities pursuant to such
registration statement; and

                  5(p) use its best efforts to comply with all applicable rules
and regulations of the Commission and make generally available to its security
holders in a regular filing on Form 10-Q or Form 10-K or otherwise provide in
accordance with Section 11(a) of the Securities Act within the period required
after the effective date of the applicable registration statement an earnings
statement satisfying the provisions of Section 11(a) of the Securities Act and
Rule 158 thereof.

         The Company may require each Holder of Registrable Securities (i) to
furnish to the Company such information regarding the proposed distribution by
such Holder of such Registrable Securities as the Company may from time to time
reasonably request in writing, and

                                      -121-

<PAGE>



(ii) to enter into an underwriting agreement and securities sales agreement in
the form contemplated by Section 5(i).


         Each Holder agrees that, upon receipt of any notice from the Company of
the happening of any event of the kind described in Section 5(e) hereof, such
Holder will immediately discontinue disposition of Registrable Securities
pursuant to a registration statement until such Holder's receipt of the copies
of the supplemented or amended prospectus contemplated by Section 5(e) hereof,
and, if so directed by the Company, such Holder will deliver to the Company (at
the expense of the Company) all copies in its possession, other than permanent
file copies then in such Holder's possession, of the prospectus covering such
Registrable Securities current at the time of receipt of such notice. If the
Company shall give any such notice to suspend the disposition of Registrable
Securities pursuant to a registration statement, the Company shall extend the
period during which the registration statement shall be maintained effective
pursuant to this Agreement by the number of days during the period from and
including the date of the giving of such notice to and including the date when
the Holders shall have received copies of the supplemented or amended prospectus
necessary to resume such dispositions.

         (f)      Hold-Back Agreements.

                  6(a) Restrictions on Public Sale by Holders. By electing to
include Registrable Securities in a registration statement filed pursuant to
Section 3 or Section 4 hereof, each such Holder of Registrable Securities shall
be deemed to have agreed not to effect any public sale or public distribution of
securities of the Company of the same or similar class or classes of the
securities included in the registration statement or any securities convertible
into or exchangeable or exercisable for such securities, including a sale
pursuant to Rule 144 or Rule 144A under the Securities Act, during the 15-day
period prior to, and during such period of time as may be required by the
Underwriters, but not to exceed a 180-day period beginning on, the effective
date of the registration statement (except pursuant to the registration
statement), except to the extent otherwise agreed in writing by the Managing
Underwriter.

                  6(b) Restrictions on Public Sale by the Company. The Company
shall not effect any public sale or public distribution of any securities which
are the same as or substantially similar to the Registrable Securities being
registered pursuant to a registration statement filed pursuant to Section 3 or
Section 4 hereof, or any securities convertible into or exchangeable or
exercisable for such securities during the 15-day period prior to, and during
the 180-day period beginning on, the effective date of a registration statement
(except pursuant to the registration statement).

         (g)      Black-Out Periods for Shelf Registration Statements.

                  Notwithstanding anything to the contrary in this Agreement,
(A) commencing ninety (90) days after the effectiveness of a Shelf Registration
Statement, the Company may, not more than once in any 12-month period, and one
additional time during the term of this Agreement (but not during any other
Suspension Event or within ninety (90) days after termination of any other
Suspension Event), direct the Holders to suspend sales of Registrable Securities
registered thereunder, as provided herein, if one or more of the following
events (a

                                      -122-


<PAGE>



"Suspension Event") occurs: (i) an underwritten primary offering by the Company
where the Company is advised by the Managing Underwriter(s) for such offering
that sale of Registrable Securities under the Shelf Registration Statement would
have a material adverse effect on the primary offering, or (ii) pending
negotiations relating to, or consummation of, a material corporate transaction
(x) that would require additional disclosure of material information by the
Company in the Shelf Registration Statement (or such filings), (y) as to which
the Company has a bona fide business purpose for preserving confidentiality and
(z) which renders the Company unable to comply with SEC requirements, in each
case under circumstances that would make it impractical or inadvisable to cause
the Shelf Registration Statement (or such filings) to become effective or to
promptly amend or supplement the Shelf Registration Statement on a
post-effective basis, as applicable; and (B) the Company may, not more than once
during the term of this Agreement, direct the Holders to suspend sales of
Registrable Securities registered thereunder, as provided herein, upon the
commencement (or such earlier date as may be required by law) of an underwritten
secondary offering covering not less than 5,250,000 Series C Securities, with an
aggregate minimum Market Value of $75,000,000 (a "Series C Offering Event").

                  In the case of a Suspension Event, the Company may give notice
(a "Suspension Notice") to the Holders to suspend sales of the Registrable
Securities so that the Company may correct or update the Shelf Registration
Statement (or such filings). Each such suspension shall continue only for so
long as the Suspension Event or its effect is continuing, and in no event will
any such suspension exceed ninety (90) days. In the case of a Series C Offering
Event, the Company may give notice (also a "Suspension Notice") to the Holders
to suspend sales of Registrable Securities for so long as the Company reasonably
determines is necessary and in no event shall such suspension exceed the date
one hundred and eighty (180) days after the close of the Series C Offering
Event. The Holders agree that they will not effect any sales of the Registrable
Securities pursuant to such Shelf Registration Statement (or such filings) at
any time after they have received a Suspension Notice from the Company. If so
directed by the Company, the Holders will deliver to the Company all copies of
the prospectus covering the Registrable Securities held by them at the time of
receipt of the Suspension Notice. The Holders may recommence effecting sales of
the Registrable Securities pursuant to the Shelf Registration Statement (or such
filings) following further notice to such effect (an "End of Suspension Notice")
from the Company, which End of Suspension Notice shall, in the case of a
Suspension Event, be given by the Company not later than five (5) days after the
conclusion of any Suspension Event and shall be accompanied by copies of the
supplemented or amended prospectus necessary to resume such sales. In the case
of a Series C Offering Event, the Holders may recommence effecting sales
immediately following the conclusion of the one hundred and eighty (180) day
period.

                  Notwithstanding Section 2, if the Company shall give a
Suspension Notice pursuant to this Section 7, the Company shall extend the
period during which the Shelf Registration Statement shall be maintained
effective pursuant to this Agreement by the number of days during the period

from the date of the giving of the Suspension Notice to and including the date
when the Holders shall have received the End of Suspension Notice and copies of
the supplemented or amended prospectus necessary to resume sales.


                                      -123-

<PAGE>



         (h)      Indemnification.

                  8(a) Indemnification by the Company. The Company shall
indemnify, to the extent permitted by law, each Holder of Registrable
Securities, each Person who controls such Holder (within the meaning of Section
15 of the Securities Act or Section 20 of the Exchange Act) and their respective
officers, directors, partners, employees, agents and representatives, against
all Losses caused by any untrue or alleged untrue statement of material fact
contained in any registration statement, prospectus or preliminary prospectus or
any amendment thereof or supplement thereto or any omission or alleged omission
of a material fact required to be stated therein or necessary to make the
statements therein, in light of the circumstances under which made, not
misleading, except insofar as the same are caused by or contained in any
information furnished in writing to the Company by such Holder expressly for use
therein or by such Holder's failure to deliver a copy of the registration
statement or prospectus or any amendments or supplements thereto after the
Company has furnished such Holder with a sufficient number of copies of the same
and except insofar as the same are caused by or contained in any prospectus if
such Holder failed to send or deliver a copy of any subsequent prospectus or
prospectus supplement which would have corrected such untrue or alleged untrue
statement of material fact or such omission or alleged omission of a material
fact with or prior to the delivery of written confirmation of the sale by such
Holder after the Company has furnished such Holder with a sufficient number of
copies of the same. In connection with an Underwritten Offering, the Company
will indemnify such Underwriters, each Person who controls such Underwriters
(within the meaning of Section 15 of the Securities Act or Section 20 of the
Securities Exchange Act) and their respective officers, directors, partners,
employees, agents and representatives to the same extent as provided above with
respect to the indemnification of the Holders of Registrable Securities.

                  8(b) Indemnification by Holders. In connection with any
registration statement in which Holders of Registrable Securities are
participating, each such Holder will furnish to the Company in writing such
information as the Company reasonably requests for use in connection with any
such registration statement or prospectus and, to the extent permitted by law,
will indemnify the Company, each Person who controls the Company (within the
meaning of Section 15 of the Securities Act or Section 20 of the Exchange Act)
and their respective officers, directors, partners, employees, agents and
representatives against any Losses arising out of or based upon any untrue or
alleged untrue statement of a material fact contained in any registration
statement, prospectus, or form of prospectus, or arising out of or based upon
any omission or alleged omission of a material fact required to be stated
therein or necessary to make the statements therein, in light of the

circumstances under which made, not misleading, to the extent, but only to the
extent, that such untrue or alleged untrue statement is contained in, or such
omission or alleged omission is required to be contained in, any information so
furnished in writing by such Holder to the Company expressly for use in such
registration statement or prospectus and that such statement or omission was
relied upon by the Company in preparation of such registration statement,
prospectus or form of prospectus; provided, however, that such Holder of
Registrable Securities shall not be liable in any such case to the extent that
the Holder has furnished in writing to the Company prior to the filing of any
such registration statement or prospectus or amendment or supplement thereto
information expressly for use in such registration statement or prospectus or
any amendment or supplement thereto which corrected or made not misleading,
information previously furnished to the Company, and the Company

                                      -124-

<PAGE>



failed to include such information therein. In no event shall the liability of
any selling Holder of Registrable Securities hereunder be greater in amount than
the dollar amount of the proceeds (net of payment of all expenses) received by
such Holder upon the sale of the Registrable Securities giving rise to such
indemnification obligation. Such indemnity shall remain in full force and effect
regardless of any investigation made by or on behalf of such indemnified party.

                  8(c) Conduct of Indemnification Proceedings. If any Person
shall be entitled to indemnity hereunder such indemnified party shall give
prompt notice to the party or parties from which such indemnity is sought of the
commencement of any Proceeding with respect to which such indemnified party
seeks indemnification or contribution pursuant hereto; provided, however, that
the failure to so notify the indemnifying parties shall not relieve the
indemnifying parties from any obligation or liability except to the extent that
the indemnifying parties have been prejudiced by such failure. The indemnifying
parties shall have the right, exercisable by giving written notice to an
indemnified party promptly after the receipt of written notice from such
indemnified party of such Proceeding, to assume, at the indemnifying parties'
expense, the defense of any such Proceeding, with counsel reasonably
satisfactory to such indemnified party; provided, however, that an indemnified
party or parties (if more than one such indemnified party is named in any
Proceeding) shall have the right to employ separate counsel in any such
Proceeding and to participate in the defense thereof, but the fees and expenses
of such counsel shall be at the expense of such indemnified party or parties
unless the parties to such Proceeding include both the indemnified party or
parties and the indemnifying party or parties, and there exists, in the opinion
of the parties' counsel, a conflict between one or more indemnifying parties and
one or more indemnified parties, in which case the indemnifying parties shall,
in connection with any one such Proceeding or separate but substantially similar
or related Proceedings in the same jurisdiction, arising out of the same general
allegations or circumstances, be liable for the fees and expenses of not more
than one separate firm of attorneys (together with appropriate local counsel) at
any time for such indemnified party or parties. If an indemnifying party assumes
the defense of such Proceeding, the indemnifying, parties will not be subject to

any liability for any settlement made by the indemnified party without its or
their consent (such consent not to be unreasonably withheld).

                  8(d) Contribution. If the indemnification provided for in this
Section 8 is unavailable to an indemnified party or is insufficient to hold such
indemnified party harmless for any Losses in respect of which this Section 8
would otherwise apply by its terms, then each applicable indemnifying party, in
lieu of indemnifying such indemnified party, shall have an obligation to
contribute to the amount paid or payable by such indemnified party as a result
of such Losses, in such proportion as is appropriate to reflect the relative
fault of the indemnifying party, on the one hand, and such indemnified party, on
the other hand, in connection with the actions, statements or omissions that
resulted in such Losses as well as any other relevant equitable considerations.
The relative fault of such indemnifying party, on the one hand, and indemnified
party, on the other hand, shall be determined by reference to, among other
things, whether any action in question, including any untrue or alleged untrue
statement of a material fact or omission or alleged omission to state a material
fact, has been taken by, or relates to information supplied by, such
indemnifying party or indemnified party, and the parties' relative intent,
knowledge, access to information and opportunity to correct or prevent any such
action, statement or omission. The amount paid or payable by a party as a result
of any Losses shall be deemed to include any legal or other fees or expenses
incurred by such party in connection

                                      -125-

<PAGE>



with any Proceeding, to the extent such party would have been indemnified for
such expenses under Section 8(c), if the indemnification provided for in Section
8(a) or Section 8(b) was available to such party. The parties hereto agree that
it would not be just and equitable if contribution pursuant to this Section 8(d)
were determined by pro rata allocation or by any other method of allocation that
does not take account of the equitable considerations referred to in the
immediately preceding paragraph. Notwithstanding the provisions of this Section
8(d), an indemnifying party that is a selling Holder of Registrable Securities
shall not be required to contribute any amount in excess of the amount by which
the net proceeds received by such indemnifying party exceeds the amount of any
damages that such indemnifying party has otherwise been required to pay by
reason of such untrue or alleged untrue statement or omission or alleged
omission. No person adjudged guilty of fraudulent misrepresentation (within the
meaning of Section 11(f) of the Securities Act) shall be entitled to
contribution from any Person who was not guilty of such fraudulent
misrepresentation.

         (i)      Miscellaneous.

                  9(a) Amendments and Waivers. The provisions of this Agreement,
including the provisions of this sentence, may not be amended, modified or
supplemented, and waivers or consents to departures from the provisions hereof
may not be given unless the Company has obtained the written consent of the
Holders of a majority of the Registrable Securities; provided, however, that no

amendment, modification or supplement or waiver or consent to the departure with
respect to the provisions of Section 2, Section 3, Section 4, Section 7, or
Section 8 hereof shall be effective as against any Holder of Registrable
Securities unless consented to in writing by such Holder of Registrable
Securities.

                  9(b) Notices. All notices and other communications provided
for or permitted hereunder shall be made in writing by hand-delivery, registered
first-class mail, telex, telecopier, or any courier guaranteeing overnight
delivery (i) if to a Holder, at the most current address given by such Holder to
the Company by means of a notice given in accordance with the provisions of this
Section 9(b) (ii) if to the Company, at 2440 Research Boulevard, Suite 400,
Rockville, MD 20850, Attention: General Counsel, and thereafter at such other
address, notice of which is given in accordance with the provisions of this
Section 9(b).

         All such notices and communications shall be deemed to have been duly
given: at the time delivered by hand, if personally delivered; five business
days after being deposited in the mail, postage prepaid, if mailed; when
answered back, if telexed; when receipt is acknowledged, if telecopied; and on
the next business day if timely delivered to an air courier guaranteeing
overnight delivery.

                  9(c) Successors and Assigns. This Agreement shall inure to the
benefit of and be binding upon the successors, assigns and transferees of each
of the parties, including, without limitation and without the need for an
express assignment, subsequent Holders. If any successor, assignee or transferee
of any Holder shall acquire Registrable Securities, in any manner, whether by
operation of law or otherwise, such Registrable Securities shall be held subject
to the terms of this Agreement, and by taking and holding such Registrable
Securities such Person shall be entitled to receive the benefits hereof and
shall be conclusively deemed to have agreed to be bound by all of the terms and
provisions hereof. Notwithstanding the

                                      -126-

<PAGE>



foregoing, only Matra, as a Holder of Registrable Securities, may request an
Underwritten Offering pursuant to Section 3(a) with respect to Registrable
Securities with a Market Value, as of the date of such request, of less than $20
million.

                  9(d) Counterparts. This Agreement may be executed in any
number of counterparts and by the parties hereto in, separate counterparts, each
of which when so executed shall be deemed to be an original and all of which
taken together shall constitute one and the same agreement.

                  9(e) Headings. The headings in this Agreement are for
convenience of reference only and shall not limit or otherwise affect the
meaning hereof.


                  9(f) Governing Law; Consent to Jurisdiction. THIS AGREEMENT
AND THE DUTIES AND OBLIGATIONS OF THE PARTIES HERETO SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE INTERNAL LAWS OF THE STATE OF NEW YORK, WITHOUT
GIVING EFFECT TO THE CONFLICTS OF LAW PROVISIONS THEREOF. EACH OF THE PARTIES
HERETO AGREES TO SUBMIT TO THE NON-EXCLUSIVE JURISDICTION OF THE COURTS OF THE
STATE OF NEW YORK IN ANY ACTION OR PROCEEDING ARISING OUT OF OR RELATING TO THIS
AGREEMENT.

                  9(g) Severability. In the event that any one or more of the
provisions contained herein, or the application thereof in any circumstance, is
held invalid, illegal or unenforceable, the validity, legality and
enforceability of any such provision in every other respect and of the remaining
provisions contained herein shall not be affected or impaired thereby.

                  9(h) Specific Performance. The parties hereto acknowledge that
there would be no adequate remedy at law if any party fails to perform any of
its obligations hereunder, and accordingly agree that each party, in addition to
any other remedy to which it may be entitled at law or in equity, shall be
entitled to compel specific performance of the obligations of any other party
under this Agreement in accordance with the terms and conditions of this
Agreement in any court of the United States of America or any State thereof
having jurisdiction.

                  9(i) Entire Agreement. This Agreement is intended by the
parties as a final expression of their agreement and intended to be a complete
and exclusive statement of the agreement and understanding of the parties hereto
in respect of the subject matter contained herein. This Agreement supersedes an
prior oral or written agreements, commitments or understandings between the
parties with respect to the matters provided for herein.


                                      -127-

<PAGE>



         IN WITNESS WHEREOF, the parties have executed this Agreement as of the
date first written above.

                                        ORION NETWORK SYSTEMS, INC.


                                        By:  _____________________________
                                             Name:
                                             Title:


                                        BRITISH AEROSPACE HOLDINGS, INC.


                                        By:  _____________________________
                                             Name:
                                             Title:


                                        MATRA MARCONI SPACE UK LIMITED


                                        By:  _____________________________
                                             Name:
                                             Title:


                                      -128-

<PAGE>
                                                          EXHIBIT D
                                                          INFORMATION REGARDING
                                                          SUBSIDIARIES

                                  SUBSIDIARIES

<TABLE>
<CAPTION>
                                                                                             Percentage of   
                                                                                             equity interests
                                    Jurisdiction of           Jurisdictions                  owned by the    
                                    organization or           where qualified to             Company or a    
Name                                incorporation             do business                    Subsidiary      
- ----                                -------------             -----------                    ----------      
<S>                                    <C>                    <C>                                <C>

(1)   Orion Satellite                  Delaware               Maryland, Virginia                 100%
      Corporation

(2)   OrionNet, Inc.                   Delaware               District of Columbia,              100%
                                                              Illinois, Massachusetts,
                                                              Michigan, New Jersey,
                                                              New York, Ohio, Oklahoma
                                                              Pennsylvania, Rhode
                                                              Island, Virginia

(3)   Asia Pacific Space               Delaware               Maryland                           100%
      and Communications, Ltd.

(4)   OrionNet                         Delaware               New Jersey                         100%
      Finance Corporation

(5)   Orion Asia
      Pacific Corporation              Delaware               Maryland                           100%

(6)   Orion Atlantic
      Europe, Inc.                     Delaware               Maryland, Virginia                 100%

(7)   Orion Oldco                      Delaware               California, Maryland               100%
      Services, Inc.

(8)   International                    England/Wales          England/Wales                       60%
      Technology Gateway
      (U.K.) Limited

(9)   International                    Delaware               Maryland, Virginia                 100%
      Private Satellite
      Partners, L.P.
</TABLE>

                                      -129-


<PAGE>

                                                                     EXHIBIT 3

                                                                EXECUTION COPY


                          REGISTRATION RIGHTS AGREEMENT


         THIS REGISTRATION RIGHTS AGREEMENT (the "Agreement") is made and
entered into as of January 31, 1997, between and among Orion Network Systems,
Inc., formerly known as Orion Newco Services, Inc., a Delaware corporation (the
"Company"), British Aerospace Holdings, Inc., a Delaware corporation ("BAe"),
and Matra Marconi Space UK Limited, a company organized under the laws of
England and Wales ("Matra") (together, the "Purchasers").

         WHEREAS, the Company proposes to issue and sell to the Purchasers
$60,000,000 aggregate principal amount of its Convertible Junior Subordinated
Debentures Due February 1, 2012 (Interest Payable in Common Stock) (the
"Debentures"), pursuant to the terms of a Debenture Purchase Agreement, dated as
of January 13, 1997, as amended as of January 31, 1997 (the "Debenture Purchase
Agreement");

         WHEREAS, as a condition to the Purchasers' obligations under the
Debenture Purchase Agreement, the Company agrees with each of the Purchasers for
their benefit and for the benefit of the holders from time to time of the
Registrable Securities (as defined herein) whose names appear in the register
maintained by the Company's registrar in accordance with the provisions of the
Debenture Purchase Agreement (each of the foregoing a "Holder," and collectively
the "Holders"), to grant to the Purchasers certain registration rights;

         WHEREAS, the purchase of the Debentures under the Debenture Purchase
Agreement and this Agreement are conditioned upon, among other things, the
consummation of the transactions contemplated under the Section 351 Exchange
Agreement and Plan of Conversion, dated as of June, 1996, as amended, and as may
be further amended from time to time (the "Exchange Agreement"), among Orion
Oldco Services, Inc., formerly known as Orion Network Systems, Inc., a Delaware
corporation ("ONS"), International Private Satellite Partners, L.P., a Delaware
limited partnership, Orion Satellite Corporation, a Delaware corporation, and
British Aerospace Communications, Inc. ("BAC"), a Delaware corporation; COM DEV
Satellite Communications Limited, a Canadian corporation ("COM DEV"); Kingston
Communications International Limited, a company incorporated under the laws of
England ("Kingston"); Lockheed Martin Commercial Launch Services, Inc., a
Delaware corporation ("Lockheed Martin"); MCN Sat US, Inc., a Delaware
corporation ("MCN Sat"); and Trans-Atlantic Satellite, Inc., a Delaware
corporation ("TA Sat") (collectively, BAC, COM DEV, Kingston, Lockheed Martin,
MCN Sat and TA Sat are referred to herein as the "Exchanging Partners").

         NOW, THEREFORE, in consideration of the premises, the parties hereby
consent and agree, as follows:




<PAGE>



         1.       Definitions.

         As used in this Agreement, the following capitalized defined terms
shall have the following meanings:

         Business Day: any day other than a Saturday or Sunday or day on which
banking institutions in the State of New York are not required to be open.

         Closing Date: the date of closing of the Company's sale of the
Debentures to the Purchasers as contemplated by the Debenture Purchase
Agreement.

         Commission:  the Securities and Exchange Commission.

         Common Stock: the common stock, par value $.01 per share, of the
Company.

         Company: the meaning set forth in the preamble and shall also include
the Company's successors or other parties who succeed to the Company's
obligations hereunder.

         Debentures: the Convertible Junior Subordinated Debentures Due February
1, 2012 (Interest Payable in Common Stock) of the Company.

         Debenture Purchase Agreement:  the meaning set forth in the preamble.

         Eligible Series C Securities: the Series C Securities which a holder
thereof is permitted to sell under the terms of the Transfer Restriction
Agreements.

         Exchange Act: the Securities Exchange Act of 1934, as amended from time
to time.

         Exchange Agreement:  the meaning set forth in the preamble.

         Exchanging Partner:  the meaning set forth in the preamble.

         Holder:  any holder of Registrable Securities.

         Initial Shelf Registrable Securities: Registrable Securities, excluding
the shares of Common Stock or other securities issued or issuable upon
conversion of the Debentures.

         Initial Shelf Registration Statement: the Shelf Registration Statement
filed by the Company pursuant to Section 2(a).

         Losses: any losses, claims, damages, liabilities, costs and expenses,
including, but not limited to, reasonable attorney's fees.



                                       -2-

<PAGE>



         Managing Underwriters: the investment banker or investment bankers and
manager or managers that shall administer an Underwritten Offering of the
securities covered by any registration statement.

         Market Value: with respect to a specified date, the aggregate closing
price of such shares of Common Stock on the principal national stock exchange or
automated quotation system upon which the Common Stock is listed or quoted,
averaged over a period of twenty (20) consecutive Business Days prior to such
date. If during this period the Common Stock is not listed on any securities
exchange, quoted on the Nasdaq National Market, or quoted in the
over-the-counter market, the Market Value will be the fair value of the Common
Stock determined by agreement between the Company and the Holders of a majority
of the Registrable Securities. If such parties are unable to reach agreement
within a reasonable period of time, the fair value of the Common Stock shall be
determined by an independent appraiser experienced in valuing such type of
consideration jointly selected by the Company and the Holders of a majority of
the Registrable Securities. The determination of such appraiser shall be final
and binding upon the parties, and the fees and expenses of such appraiser shall
be borne by the Company.

         Other Registrable Stock: shares of Common Stock which the Company is
obligated to register, or include in a registration statement under the
Securities Act, under any Other Registration Rights Agreement.

         Other Registration Rights Agreement: the following agreements entered
into by ONS on or before the date of the Exchange Agreement under which ONS is
obligated to register, or include in a registration statement under the
Securities Act, shares of capital stock of ONS, and amendments and supplements
to any such agreement entered into on or before the date of the Exchange
Agreement, in each case as such agreement will be amended or assigned prior to
the closing under the Exchange Agreement to transfer all of the ONS rights and
obligations under each of such agreements to the Company: (i) the Registration
Rights Agreement dated as of June 17, 1994, among ONS and the Schedule of
Investors set forth therein, as amended (the "Recent PRRAA")); (ii) the
Registration Rights Agreement, dated as of April 29, 1994, between ONS and Space
Systems/Loral, Inc.; and (iii) the Series C Registration Rights Agreement.

         Person: any individual, partnership, corporation, limited liability
company, trust, or unincorporated organization, or a government or agency or
political subdivision thereof.

         Piggyback Registration: the registration by the Company of the Common
Stock (whether for its own account or for the account of others) under the
Securities Act, other than pursuant to a registration statement filed pursuant
to the provisions of Section 2 or Section 3 hereof or a registration of
securities in connection with a business acquisition or combination or an
employee benefit plan.


         Proceeding: any action, suit, proceeding or investigation or written
threat thereof.


                                       -3-

<PAGE>



         Registrable Securities: regardless of who holds such securities at the
applicable time, (i) the shares of Common Stock of the Company received by BAe
in connection with the purchase by ONS of BAe's interest in Asia Pacific Space
and Communications Ltd.; (ii) the shares of Common Stock or other securities
issued or issuable upon conversion of the Debentures or issued as interest
payments pursuant to the Debenture Purchase Agreement; and (iii) the 86,505
shares of Common Stock issued pursuant to the respective Warrants of ONS dated
as of December 20, 1991, granted to BAC, exercised on December 31, 1996;
provided, however, that such securities shall cease to be Registrable Securities
when a registration statement with respect to the registration of such
securities shall have been declared effective under the Securities Act and such
securities shall have been disposed of pursuant to such registration statement.

         Registration Expenses: any and all expenses incident to the filing and
effectiveness of each registration statement and performance of or compliance by
the Company with this Agreement, including without limitation: (i) all
Commission, stock exchange or National Association of Securities Dealers, Inc.
("NASD") registration and filing fees, (ii) all fees and expenses incurred in
connection with compliance with state securities or Blue Sky laws (including
reasonable fees and disbursements of counsel in connection with Blue Sky
qualification of any of the Registrable Securities and the preparation of a Blue
Sky memorandum and compliance with the rules of the NASD, (iii) all expenses of
any Persons in preparing or assisting in preparing, word processing, printing
and distributing any registration statement, any prospectus, any amendments or
supplements thereto, any underwriting agreements, securities sales agreements,
certificates and other documents relating to the performance of and compliance
with this Agreement, (iv) all fees and expenses incurred in connection with the
listing of any of the Registrable Securities on any securities exchange or the
Nasdaq National Market, (v) the fees and disbursements of counsel for the
Company and of the independent public accountants of the Company, including the
expenses of any special audits or "cold comfort" letters required by or incident
to such performance and compliance, (vi) the reasonable fees and disbursements
of one special counsel representing the Holders of Registrable Securities, such
special counsel to be selected by the Holders of a majority of the Registrable
Securities being registered, (vii) the fees and expenses of a "qualified
independent underwriter" if required by Rule 2720(c) of the rules of the NASD in
connection with the offering of any of the Registrable Securities, (viii) the
fees and expenses of any escrow agent or custodian, and (ix) any fees and
disbursements of any Underwriters customarily paid by issuers or sellers of
securities and the reasonable fees and expenses of any special experts retained
by the Company in connection with any registration statement, but excluding
underwriting discounts and commissions and transfer taxes, if any, relating to
the sale or disposition of Registrable Securities by a Holder.


         Registration Period: a period terminating fifteen (15) years following
the Closing Date.

         Securities Act: the Securities Act of 1933, as amended from time to
time.

         Series C Preferred Stock: the Series C 6% Cumulative Redeemable
Convertible Preferred Stock of the Company.


                                       -4-

<PAGE>



         Series C Registration Rights Agreement: the Registration Rights
Agreement dated as of January 31, 1997, among the Company and the Exchanging
Partners.

         Series C Securities: the shares of Common Stock or other securities
issued or issuable upon conversion of the Series C Preferred Stock purchased by
the Exchanging Partners pursuant to the Exchange Agreement or issued as
dividends or distributions pursuant to the Certificate of Designations, Rights
and Preferences establishing the terms and relative rights and preferences of
the Series C Preferred Stock.

         Shelf Registration: a registration required to be effected pursuant to
Section 2(a).

         Shelf Registration Statement: a "shelf" registration statement of the
Company which covers the registration of Registrable Securities on a Form S-3,
and all amendments and supplements to such registration statement, including
post-effective amendments, in each case including the prospectus contained
therein, all exhibits thereto and all material incorporated by reference
therein; "Shelf Registration Statement" shall include the Initial Shelf
Registration Statement and each Top-up Shelf Registration Statement.

         Top-up Shelf Registration Statement: the meaning set forth in Section
2(b).

         Transfer Restriction Agreement: means (i) each agreement, dated on or
about the Closing Date, between the Company and any Exchanging Partner and (ii)
each subsequent agreement entered into between the Company and any Exchanging
Partner, any affiliate thereof, any transferee of Series C Preferred Stock or
Common Stock into which such Series C Preferred Stock is converted or which is
issued as a dividend on such Series C Preferred Stock or any other party
pursuant to the terms of another Transfer Restriction Agreement, in each case
which provides for restrictions on transfer of the Series C Preferred Stock or
Common Stock into which such Series C Preferred Stock is converted or which is
issued as a dividend on such Series C Preferred Stock.

         Underwriter: each Person who participates as an underwriter of
securities in a registered offering under the Securities Act.


         Underwritten Offering: a sale of Company securities by the Company or a
holder of such securities to an Underwriter or Underwriters for reoffering to
the public.

         2.       Shelf Registration.

                  2(a) Filing of Initial Shelf Registration Statement. The
Company shall prepare and cause to be filed as soon as practicable after the
date that is one hundred eighty (180) days after the Closing Date (but not later
than fifteen (15) days thereafter), the Initial Shelf Registration Statement
providing for the registration of all of the Initial Shelf Registrable
Securities. The Company shall use all its best efforts to have the Initial Shelf
Registration Statement declared effective by the Commission as soon as
practicable after filing. The

                                       -5-

<PAGE>



Company shall use its best efforts to keep the Initial Shelf Registration
Statement continuously effective for the Registration Period, or such shorter
period which will terminate when all of the Registrable Securities covered by
the Initial Shelf Registration Statement, as amended from time to time pursuant
to Section 2(b), have been sold pursuant to the Initial Shelf Registration
Statement. Notwithstanding the foregoing, except as set forth below, any Holder
who does not provide information reasonably requested by the Company in
connection with the Initial Shelf Registration Statement shall not be entitled
to have its Registrable Securities included in the Initial Shelf Registration
Statement.

                  2(b) Filing of Subsequent Shelf Registration Statements or
Amendments. The Company shall prepare and cause to be filed on or as soon as
practicable after the first anniversary of the Closing Date (but no later than
ten (10) days thereafter) and as soon as practicable after each of the
successive semi-annual interest payment dates provided for in the Debenture
Purchase Agreement (but no later than ten (10) days thereafter) an additional
Shelf Registration Statement or, at the Company's option, a post-effective
amendment to any then-effective Shelf Registration Statement (a "Top-up Shelf
Registration Statement") providing for the registration of all of the
Registrable Securities comprising shares of Common Stock or other securities
issued as interest payments pursuant to the Debenture Purchase Agreement which
have not been registered previously. The Company shall also use all reasonable
efforts to cause to be filed, as soon as practicable each time after receipt of
a written demand from a Holder (but no later than thirty (30) days thereafter),
an additional Shelf Registration Statement or, at the Company's option, a
post-effective amendment to any then-effective Shelf Registration Statement
(also a "Top-up Shelf Registration Statement") providing for the registration of
any and all of the Registrable Securities each Holder demands to be included in
such Top-up Shelf Registration Statement which have not been registered
previously; provided, however, that no such demand shall be effective before the
first anniversary of the Closing Date or after the end of the Registration

Period. The Company shall use its best efforts to have each such Shelf
Registration Statement or post-effective amendment declared effective by the
Commission as soon as practicable after filing. The Company shall use its best
efforts to keep each Top-up Shelf Registration Statement continuously effective
for the Registration Period, or such shorter period which will terminate when
all of the Registrable Securities covered by such Top-up Shelf Registration
Statement, as amended from time to time pursuant to this Section 2(b), have been
sold pursuant to such Top-up Shelf Registration Statement. Notwithstanding the
foregoing, except as set forth below, any Holder who does not provide
information reasonably requested by the Company in connection with the Top-up
Shelf Registration Statement shall not be entitled to have its Registrable
Securities included in the Top-up Shelf Registration Statement.

                  2(c) Effective Registration Statement, Amendments. A Shelf
Registration Statement pursuant to this Section 2 will not be deemed to have
become effective unless it has been declared effective by the Commission;
provided, however that if, after it has been declared effective, the offering of
any Registrable Securities pursuant to such registration statement is interfered
with by any stop order, injunction or other order or requirement of the
Commission or any other governmental agency or court, such registration
statement will be deemed not to have become effective, and the Company shall be
required to continue to use its best efforts to

                                       -6-

<PAGE>



have such registration statement declared effective. Further, the Company shall,
if necessary, supplement or amend each Shelf Registration Statement, if required
by the rules, regulations or instructions applicable to the registration form
used by the Company for such Shelf Registration Statement or by the Securities
Act or by any other rules and regulations thereunder for shelf registration.

                  2(d) Expenses. The Company shall pay any and all Registration
Expenses incident to the filing of each Shelf Registration Statement or
otherwise incident to the performance of or compliance by the Company with this
Section 2. Each Holder shall pay all underwriting discounts and commissions and
transfer taxes, if any, relating to the sale or disposition of such Holder's
Registrable Securities pursuant to the Shelf Registration Statement.

         3.       Demand Registration of Underwritten Offerings.

                  3(a) Requests for Underwritten Registration. At any time
following one hundred eighty (180) days after the Closing Date, one or more
Holders may request that the Company effect a registration under the Securities
Act of all or any of their Registrable Securities in an Underwritten Offering;
provided, however, that, unless the requesting Holder is Matra, the requesting
Holders must request registration of Registrable Securities with a Market Value,
on the date of such request, of at least $20 million; and provided, further,
that if the requesting Holder is Matra, Matra must request registration of
Registrable Securities with a Market Value, as of the date of such request, of
at least $10 million. Each request for an Underwritten Offering shall specify

the approximate number of shares of Registrable Securities requested to be
registered and the anticipated per share price range for such offering. Within
ten (10) days after receipt of any such request, the Company will give written
notice of such requested demand registration to all other Holders and, subject
to Section 3(b), will include in any such registration which constitutes an
Underwritten Offering satisfying the requirements of this Section 3(a), all
Registrable Securities with respect to which the Company has received written
requests for inclusion therein within fifteen (15) days after the date the
Company's notice is given.

                  3(b) Priority on Underwritten Offering. If the Managing
Underwriters for an Underwritten Offering advise the Company in writing that in
their reasonable opinion the aggregate number of Registrable Securities to be
included in an Underwritten Offering (together with any other shares of Common
Stock which the Company is required to include in such registration) exceeds the
number of shares which can be sold in an orderly manner in such offering within
a price range acceptable to the holders of a majority of the Registrable
Securities and Other Registrable Stock requested to be included in such
registration, the Company will include in such registration (i) first, the
maximum amount of Registrable Securities requested to be included therein, pro
rata among the respective Holders thereof on the basis of the amount of
Registrable Securities requested to be included in such registration by each
such Holder, and (ii) second, the maximum amount of Other Registrable Stock and
any other securities requested to be included therein (including by the Company,
subject to Section 3(e)), pro rata among the Company and the holders of such
Other Registrable Stock and other securities on the basis of

                                      -7-

<PAGE>



the number of shares requested to be included in such registration by the
Company and each such holder, in each case up to the greatest number of shares
of Common Stock which in the reasonable opinion of such underwriters can be sold
in an orderly manner in the price range of such offering. In no event shall any
Other Registrable Stock or any other securities be included in an Underwritten
Offering under this Section 3 unless all Registrable Securities requested to be
sold in any such offering have been included therein.

                  3(c) Restrictions on Underwritten Offerings. The Company will
not be obligated to effect more than one Underwritten Offering for Holders of
Registrable Securities within any twelve (12) month period, except as provided
in the following sentence, and will not be obligated to effect an Underwritten
Offering for Holders of Registrable Securities at any time before ninety (90)
days after the earlier of (i) the date the previous registration statement
prepared in connection with an Underwritten Offering for Holders of Registrable
Securities ceases to be effective or (ii) the date that all shares registered
thereunder have been sold. The foregoing limitation on Underwritten Offerings
within any twelve (12) month period shall not apply to a single Underwritten
Offering with respect to Registrable Securities of any Holder (other than Matra)
if the Company effected an Underwritten Offering made at Matra's request within
the preceding twelve (12) months or to a single Underwritten Offering requested

by Matra if the Company effected an Underwritten Offering with respect to
Registrable Securities of any other Holder within the preceding twelve (12)
months.

                  3(d) Selection of Underwriters. The Holders of a majority of
the Registrable Securities requested to be included in such Underwritten
Offering will have the right to select the Managing Underwriter(s) to administer
the offering; provided, first, that if the Company is successful in obtaining
the services of one or more Underwriters who have been the Managing Underwriters
for an Underwritten Offering of the Company's securities previously, such
Underwriters shall be the Managing Underwriter(s) to administer the offering;
provided, however, that such Managing Underwriter(s) shall be nationally
recognized investment banking firms approved by the Holders, which approval
shall not be unreasonably withheld; and provided, second, that if the Company
participates in the Underwritten Offering under Section 3(e), such Holders shall
obtain the Company's consent with respect to any Managing Underwriter(s) to
administer the offering, which consent shall not be unreasonably withheld.

                  3(e) Inclusion by the Company of its Common Stock in an
Underwritten Offering. If the Managing Underwriters for an Underwritten Offering
advise the Company in writing that in their opinion the aggregate number of
Registrable Securities to be included in an Underwritten Offering (together with
any Other Registrable Stock) is less than the number of shares which can be sold
in an orderly manner in such offering within a price range acceptable to the
holders of a majority of the Registrable Securities and Other Registrable Stock
requested to be included in such registration, the Company may include in such
registration, on its own behalf, up to the greatest number of shares of Common
Stock which in the opinion of such underwriters can be sold (together with the
Registrable Securities and Other Registrable Stock requested to be included in
such registration) in an orderly manner in the price range of such offering.

                                       -8-

<PAGE>




                  3(f) Participation in Underwritten Registrations.
Notwithstanding any other provision of this Section 3 to the contrary, no Person
may participate in any Underwritten Offering hereunder unless such Person (a)
agrees to sell such Person's securities on the basis provided in the applicable
underwriting arrangements and (b) completes and executes all questionnaires,
powers of attorney, indemnities, underwriting agreements and other documents
required under the terms of such underwriting arrangements; provided, however,
that no Holder of Registrable Securities included in any Underwritten Offering
shall be required to make any representations or warranties to the Company or
the underwriters other than representations and warranties regarding such Holder
and such Holder's intended method of distribution.

                  3(g) Expenses of Underwriting Offering. The Company shall pay
any and all Registration Expenses incident to the filing of each registration
statement or otherwise incident to the performance of or compliance by the
Company with this Section 3. Each Holder shall pay all underwriting discounts

and commissions and transfer taxes, if any, relating to the sale or disposition
of such Holder's Registrable Securities included in the Underwritten Offering.

                  3(h) Relationship to Shelf Registration. The rights and
obligations of the parties hereto under Section 3 shall be in addition to, and
not in lieu of, their respective rights and obligations under Section 2.

         4.       Piggyback Registration Rights.

                  4(a) Requests for Piggyback Registration. If at any time
following the date of this Agreement, the Company proposes to effect a Piggyback
Registration, the Company will give written notice to all Holders of its
intention to effect such a registration and, subject to Section 4(b) and Section
4(c), will include in such registration all Registrable Securities with respect
to which the Company has received written requests for inclusion therein within
fifteen (15) days after the date the Company's notice is given.

                  4(b) Priority on Primary Registrations. If the proposed
Piggyback Registration is an underwritten primary registration on behalf of the
Company, and the Managing Underwriters advise the Company in writing that in
their opinion the number of securities requested to be included in such
registration exceeds the number which can be sold in such offering in an orderly
manner within a price range acceptable to the Company, the Company will include
in such registration (i) first, the securities the Company proposes to sell and
the High Priority Registrable Securities (as defined in the Recent PRRAA), pro
rata among the Company and the holders of such High Priority Registrable
Securities on the basis of the number of shares requested to be included by the
Company and each such holder, (ii) second, any Other Registrable Stock requested
to be included therein, pro rata among the holders of such Other Registrable
Stock on the basis of the number of shares requested to be included in such
registration by each such holder, and (iii) third, the Registrable Securities
requested to be included in such registration, pro rata among the Holders
thereof on the basis of the amount of Registrable Securities requested to be
included by each such Holder, in each case up to the

                                       -9-

<PAGE>



greatest number of shares of Common Stock which in the reasonable opinion of
such underwriters can be sold in an orderly manner in the price range of such
offering.

                  4(c) Priority on Secondary Registrations. If a Piggyback
Registration is an underwritten secondary registration on behalf of holders of
the Company's securities (other than the Registrable Securities), and the
Managing Underwriters advise the Company in writing that in their opinion the
number of securities requested to be included in such registration exceeds the
number which can be sold in such offering without adversely affecting the
marketability of the offering, the Company will include in such registration (A)
if such registration is on behalf of holders of the Eligible Series C
Securities, (i) first, the securities requested to be included in such

registration under the Series C Registration Rights Agreement, and (ii) second,
the Registrable Securities requested to be included in such registration and any
Other Registrable Stock (excluding Eligible Series C Securities) and any other
securities requested to be included therein (including by the Company, subject
to Section 3(e)), pro rata among such Holders and the holders of such Other
Registrable Stock and other securities on the basis of the number of shares
requested to be included in such registration by each such holder, in each case
up to the greatest number of shares of Common Stock which in the reasonable
opinion of such underwriters can be sold in an orderly manner in the price range
of such offering; or (B) if such registration is not on behalf of holders of the
Eligible Series C Securities (i) first, the securities requested to be included
therein by the holders requesting such registration, and (ii) second, the
greatest number of the Registrable Securities, Other Registrable Stock and any
other securities requested to be included therein (including by the Company,
subject to Section 3(e)), pro rata among such Holders and the holders of such
Other Registrable Stock and other securities on the basis of the number of
shares requested to be included in such registration by each such holder, in
each case up to the greatest number of shares of Common Stock which in the
reasonable opinion of such underwriters can be sold in an orderly manner in the
price range of such offering.

                  4(d) Participation in Piggyback Registrations. Notwithstanding
any other provision of this Section 4 to the contrary, no Person may participate
in any Piggyback Registrations hereunder unless such Person (i) agrees to sell
such Person's securities on the basis provided in the applicable underwriting
arrangements and (ii) completes and executes all questionnaires, powers of
attorney, indemnities, underwriting agreements and other documents required
under the terms of such underwriting arrangements; provided, however, that no
Holder of Registrable Securities included in any Piggyback Registration shall be
required to make any representations or warranties to the Company or the
underwriters other than representations and warranties regarding such Holder and
such Holder's intended method of distribution.

                  4(e) Expenses of Piggyback Registration. The Company shall pay
any and all Registration Expenses incident to the filing of each registration
statement or otherwise incident to the performance of or compliance by the
Company with this Section 4. Each Holder shall pay all underwriting discounts
and commissions and transfer taxes, if any, relating to the sale or disposition
of such Holder's Registrable Securities included in the Piggyback Registration.

                                      -10-

<PAGE>




         5.       Registration Procedures.

         In connection with the obligations of the Company with respect to a
registration statement pursuant to Section 2, Section 3 or Section 4 hereof, the
Company shall effect or cause to be effected the registration of the Registrable
Securities under the Securities Act to permit the sale of such Registrable
Securities by the Holders in accordance with their intended method or methods of

distribution, and the Company shall:

                  5(a) prepare and file with the Commission a registration
statement with respect to such Registrable Securities and use its best efforts
to cause such registration statement to become effective within the time period
required hereunder (provided that before filing a registration statement or
prospectus or any amendments or supplements thereto, the Company will furnish to
one counsel selected by the holders of 70% of the Registrable Securities
(together with any Other Registrable Stock) covered by such registration
statement copies of all such documents proposed to be filed, which documents
will be subject to the review of such counsel, and the Company will incorporate
in such registration statement the reasonable comments of such counsel not
inconsistent with the Company's disclosure obligations under applicable
securities laws;

                  5(b) prepare and file with the Commission such amendments and
supplements to such registration statement and the prospectus used in connection
therewith as may be necessary to keep such registration statement effective for
the period required hereunder (or if no period is so required, a period of not
less than one hundred eighty (180) days or such shorter period which is
sufficient to complete the distribution of the securities registered under the
registration statement) and comply with the provisions of the Securities Act
with respect to the disposition of all securities covered by such registration
statement during such period in accordance with the intended methods of
disposition by the sellers thereof set forth in such registration statement;

                  5(c) furnish to each seller of Registrable Securities, the
Managing Underwriters, if any, and their respective counsel, not less than five
(5) Business Days prior to the filing thereof with the Commission, such number
of copies of such registration statement, each amendment and supplement thereto,
the prospectus included in such registration statement (including each
preliminary prospectus) and such other documents as such seller may reasonably
request in order to facilitate the disposition of the Registrable Securities
owned by such seller and to use its best efforts to reflect in each such
document, when so filed with the Commission, such comments as the sellers of
Registrable Securities or their counsel shall reasonably propose;

                  5(d) use its best efforts to register or qualify such
Registrable Securities under such other securities or blue sky laws of such
jurisdictions as any seller reasonably requests and do any and all other acts
and things which may be reasonably necessary or advisable to enable such seller
to consummate the disposition in such jurisdictions of the Registrable
Securities owned by such seller (provided that the Company will not be required
to (i) qualify generally to do business in any jurisdiction where it would not
otherwise be required to qualify but for this

                                      -11-

<PAGE>



subparagraph, (ii) subject itself to taxation in any such jurisdiction or (iii)
consent to general service of process in any such jurisdiction);


                  5(e) notify each seller of such Registrable Securities as
promptly as practicable in any of the following circumstances: (i) at any time
when a prospectus relating thereto is required to be delivered under the
Securities Act, of the happening of any event as a result of which the
prospectus included in such registration statement contains an untrue statement
of a material fact or omits any fact necessary to make the statements therein
not misleading, and, at the request of any such seller, the Company will prepare
a supplement or amendment to such prospectus so that, as thereafter delivered to
the purchasers of such Registrable Securities, such prospectus will not contain
an untrue statement of a material fact or omit to state any fact necessary to
make the statements therein not misleading; (ii) when a registration statement
and any amendment thereto has been filed with the Commission and when the
registration statement or any post-effective amendment thereto has become
effective; (iii) of any request by the Commission for amendment or supplements
to the registration statement or the prospectus included therein or for
additional information; (iv) of the issuance by the Commission of any stop order
suspending the effectiveness of the registration statement or the initiation of
any proceedings for that purpose; and (v) the receipt by the Company of any
notification with respect to the suspension of the qualification of the
securities included therein for sale in any jurisdiction or the initiation of
any proceeding for such purpose;

                  5(f) cause all such Registrable Securities to be listed on
each securities exchange on which similar securities issued by the Company are
then listed and, if not so listed, to be listed on the NASD automated quotation
system and, if listed on the NASD automated quotation system, use its best
efforts to secure designation of all such Registrable Securities covered by such
registration statement as a Nasdaq "national market system security" within the
meaning of Rule 11Aa2-1 of the Exchange Act or, failing that, to secure Nasdaq
authorization for such Registrable Securities and without limiting the
generality of the foregoing, to arrange for at least two market makers to
register as such with respect to such Registrable Securities with the NASD;

                  5(g) provide a transfer agent and registrar for all such
Registrable Securities not later than the effective date of such registration
statement;

                  5(h) if requested, promptly incorporate in any registration
statement or prospectus, if necessary, pursuant to a supplement or
post-effective amendment to such registration statement, such information as the
Managing Underwriters, if any, or the holders of a majority of Registrable
Securities and Other Registrable Securities being registered reasonably request
to have included therein and shall make all required filings of such prospectus
supplement or post-effective amendment as soon as practicable after the Company
is notified of the matters to be incorporated in such prospectus supplement or
post-effective amendment;

                  5(i) enter into such agreements on terms reasonably acceptable
to the Company (including underwriting agreements) in form, scope and substance
as are customary in

                                      -12-


<PAGE>



underwritten offerings, and take all other reasonable actions necessary to
facilitate the registration or the disposition of the Registrable Securities
included in any registration statement;

                  5(j) (i) make reasonably available at reasonable times for
inspection by the Holders of Registrable Securities to be registered thereunder,
any underwriter participating in any disposition pursuant to such registration
statement, and any attorney, accountant or other agent retained by the Holders
or such underwriters, at the office where normally kept during normal business
hours, all financial and other records, pertinent corporation documents and
properties of the Company and its subsidiaries, and cause the Company's
officers, directors and employees to supply all relevant information reasonably
requested by the Holders, or any underwriters, attorney, accountant or other
agent in connection with the registration statement as is customary for similar
due diligence examinations, provided, however, that such persons shall first
agree in writing with the Company that any information that is reasonably and in
good faith designated by the Company in writing as confidential at the time of
delivery of such information shall be kept confidential by such persons; (ii)
obtain opinions of counsel to the Company and updates thereof (which counsel, if
different from counsel to the Company referred to in the Debenture Purchase
Agreement, shall be reasonably satisfactory to the Holders of a majority of the
Registrable Securities to be registered thereunder, the underwriters, if any,
and their respective counsel) addressed to each selling Holder covering such
matters in form, scope and substance as are customary in underwritten offerings;
(iii) obtain "cold comfort" letters (or, in the case of any person that does not
satisfy the conditions for receipt of a "cold comfort" letter specified in
Statement on Auditing Standards No. 72, an "agreed-upon procedures letter") and
updates thereof from the independent certified public accountants of the Company
(and, if necessary, any other independent certified public accountants of any
subsidiary of the Company or of any business acquired by the Company for which
financial statements and financial data are, or are required to be, included in
the registration statement), addressed where reasonably practicable to each
selling Holder of Registrable Securities registered thereunder, and the
underwriters, if any, in customary form and covering matters of the type
customarily covered in "cold comfort" letters in connection with primary
underwritten offerings; and (iv) deliver such documents and certificates as may
be reasonably requested by the holders of a majority of the Registrable
Securities and Other Registrable Securities to be registered and the Managing
Underwriters, if any, including those to evidence compliance with Section 5(e).
The foregoing actions set forth in clauses (ii), (iii) and (iv) of this Section
5(j) shall be performed at (A) the effectiveness of such registration statement
and each post-effective amendment thereto and (B) each closing under any
underwriting or similar agreement as and to the extent required thereunder;

                  5(k) otherwise use its best efforts to comply with all
applicable rules and regulations of the Commission;

                  5(l) use its best efforts to cause such Registrable Securities
covered by such registration statement to be registered with or approved by such
other governmental agencies or authorities as may be necessary to enable the

sellers thereof to consummate the disposition of such Registrable Securities;

                                     -13-

<PAGE>




                  5(m) take all such action as may be necessary so that (i) any
registration statement and any amendment thereto and any prospectus forming part
thereof and any amendment or supplement thereto (and each report or other
document incorporated therein by reference in each case) complies in all
material respects with the Securities Act and the Exchange Act and the
respective rules and regulations thereunder; (ii) any registration statement and
any amendment thereto does not, when it becomes effective, contain an untrue
statement of a material fact or omit to state a material fact required to be
stated therein or necessary to make the statements therein not misleading; and
(iii) any prospectus forming part of any registration statement, and any
amendment or supplement to such prospectus, does not include an untrue statement
of a material fact or omit to state a material fact necessary in order to make
the statements therein, in light of the circumstances under which they were
made, not misleading;

                  5(n) use its best efforts to prevent the issuance, and if
issued to obtain the withdrawal, of any order suspending the effectiveness of
any registration statement at the earliest possible time;

                  5(o) unless any Registrable Securities shall be in book-entry
form, cooperate with the Holders to facilitate the timely preparation and
delivery of certificates representing Registrable Securities to be sold pursuant
to any registration statement free of any restrictive legend and in such
permitted denominations and registered in such names as the Holders may request
in connection with the sale of Registrable Securities pursuant to such
registration statement; and

                  5(p) use its best efforts to comply with all applicable rules
and regulations of the Commission and make generally available to its security
holders in a regular filing on Form 10-Q or Form 10-K or otherwise provide in
accordance with Section 11(a) of the Securities Act within the period required
after the effective date of the applicable registration statement an earnings
statement satisfying the provisions of Section 11(a) of the Securities Act and
Rule 158 thereof.

         The Company may require each Holder of Registrable Securities (i) to
furnish to the Company such information regarding the proposed distribution by
such Holder of such Registrable Securities as the Company may from time to time
reasonably request in writing, and (ii) to enter into an underwriting agreement
and securities sales agreement in the form contemplated by Section 5(i).

         Each Holder agrees that, upon receipt of any notice from the Company of
the happening of any event of the kind described in Section 5(e) hereof, such
Holder will immediately discontinue disposition of Registrable Securities
pursuant to a registration statement until such Holder's receipt of the copies

of the supplemented or amended prospectus contemplated by Section 5(e) hereof,
and, if so directed by the Company, such Holder will deliver to the Company (at
the expense of the Company) all copies in its possession, other than permanent
file copies then in such Holder's possession, of the prospectus covering such
Registrable Securities current at the time of receipt of such notice. If the
Company shall give any such notice to

                                      -14-

<PAGE>



suspend the disposition of Registrable Securities pursuant to a registration
statement, the Company shall extend the period during which the registration
statement shall be maintained effective pursuant to this Agreement by the number
of days during the period from and including the date of the giving of such
notice to and including the date when the Holders shall have received copies of
the supplemented or amended prospectus necessary to resume such dispositions.

         6.       Hold-Back Agreements.

                  6(a) Restrictions on Public Sale by Holders. By electing to
include Registrable Securities in a registration statement filed pursuant to
Section 3 or Section 4 hereof, each such Holder of Registrable Securities shall
be deemed to have agreed not to effect any public sale or public distribution of
securities of the Company of the same or similar class or classes of the
securities included in the registration statement or any securities convertible
into or exchangeable or exercisable for such securities, including a sale
pursuant to Rule 144 or Rule 144A under the Securities Act, during the 15-day
period prior to, and during such period of time as may be required by the
Underwriters, but not to exceed a 180-day period beginning on, the effective
date of the registration statement (except pursuant to the registration
statement), except to the extent otherwise agreed in writing by the Managing
Underwriter.

                  6(b) Restrictions on Public Sale by the Company. The Company
shall not effect any public sale or public distribution of any securities which
are the same as or substantially similar to the Registrable Securities being
registered pursuant to a registration statement filed pursuant to Section 3 or
Section 4 hereof, or any securities convertible into or exchangeable or
exercisable for such securities during the 15-day period prior to, and during
the 180-day period beginning on, the effective date of a registration statement
(except pursuant to the registration statement).

         7.       Black-Out Periods for Shelf Registration Statements.

                  Notwithstanding anything to the contrary in this Agreement,
(A) commencing ninety (90) days after the effectiveness of a Shelf Registration
Statement, the Company may, not more than once in any 12-month period, and one
additional time during the term of this Agreement (but not during any other
Suspension Event or within ninety (90) days after termination of any other
Suspension Event), direct the Holders to suspend sales of Registrable Securities
registered thereunder, as provided herein, if one or more of the following

events (a "Suspension Event") occurs: (i) an underwritten primary offering by
the Company where the Company is advised by the Managing Underwriter(s) for such
offering that sale of Registrable Securities under the Shelf Registration
Statement would have a material adverse effect on the primary offering, or (ii)
pending negotiations relating to, or consummation of, a material corporate
transaction (x) that would require additional disclosure of material information
by the Company in the Shelf Registration Statement (or such filings), (y) as to
which the Company has a bona fide business purpose for preserving
confidentiality and (z) which renders the Company unable to comply with SEC
requirements, in each case under circumstances that would make it

                                      -15-

<PAGE>



impractical or inadvisable to cause the Shelf Registration Statement (or such
filings) to become effective or to promptly amend or supplement the Shelf
Registration Statement on a post-effective basis, as applicable; and (B) the
Company may, not more than once during the term of this Agreement, direct the
Holders to suspend sales of Registrable Securities registered thereunder, as
provided herein, upon the commencement (or such earlier date as may be required
by law) of an underwritten secondary offering covering not less than 5,250,000
Series C Securities, with an aggregate minimum Market Value of $75,000,000 (a
"Series C Offering Event").

                  In the case of a Suspension Event, the Company may give notice
(a "Suspension Notice") to the Holders to suspend sales of the Registrable
Securities so that the Company may correct or update the Shelf Registration
Statement (or such filings). Each such suspension shall continue only for so
long as the Suspension Event or its effect is continuing, and in no event will
any such suspension exceed ninety (90) days. In the case of a Series C Offering
Event, the Company may give notice (also a "Suspension Notice") to the Holders
to suspend sales of Registrable Securities for so long as the Company reasonably
determines is necessary and in no event shall such suspension exceed the date
one hundred and eighty (180) days after the close of the Series C Offering
Event. The Holders agree that they will not effect any sales of the Registrable
Securities pursuant to such Shelf Registration Statement (or such filings) at
any time after they have received a Suspension Notice from the Company. If so
directed by the Company, the Holders will deliver to the Company all copies of
the prospectus covering the Registrable Securities held by them at the time of
receipt of the Suspension Notice. The Holders may recommence effecting sales of
the Registrable Securities pursuant to the Shelf Registration Statement (or such
filings) following further notice to such effect (an "End of Suspension Notice")
from the Company, which End of Suspension Notice shall, in the case of a
Suspension Event, be given by the Company not later than five (5) days after the
conclusion of any Suspension Event and shall be accompanied by copies of the
supplemented or amended prospectus necessary to resume such sales. In the case
of a Series C Offering Event, the Holders may recommence effecting sales
immediately following the conclusion of the one hundred and eighty (180) day
period.

                  Notwithstanding Section 2, if the Company shall give a

Suspension Notice pursuant to this Section 7, the Company shall extend the
period during which the Shelf Registration Statement shall be maintained
effective pursuant to this Agreement by the number of days during the period
from the date of the giving of the Suspension Notice to and including the date
when the Holders shall have received the End of Suspension Notice and copies of
the supplemented or amended prospectus necessary to resume sales.

         8.       Indemnification.

                  8(a) Indemnification by the Company. The Company shall
indemnify, to the extent permitted by law, each Holder of Registrable
Securities, each Person who controls such Holder (within the meaning of Section
15 of the Securities Act or Section 20 of the Exchange Act) and their respective
officers, directors, partners, employees, agents and representatives,

                                      -16-

<PAGE>



against all Losses caused by any untrue or alleged untrue statement of material
fact contained in any registration statement, prospectus or preliminary
prospectus or any amendment thereof or supplement thereto or any omission or
alleged omission of a material fact required to be stated therein or necessary
to make the statements therein, in light of the circumstances under which made,
not misleading, except insofar as the same are caused by or contained in any
information furnished in writing to the Company by such Holder expressly for use
therein or by such Holder's failure to deliver a copy of the registration
statement or prospectus or any amendments or supplements thereto after the
Company has furnished such Holder with a sufficient number of copies of the same
and except insofar as the same are caused by or contained in any prospectus if
such Holder failed to send or deliver a copy of any subsequent prospectus or
prospectus supplement which would have corrected such untrue or alleged untrue
statement of material fact or such omission or alleged omission of a material
fact with or prior to the delivery of written confirmation of the sale by such
Holder after the Company has furnished such Holder with a sufficient number of
copies of the same. In connection with an Underwritten Offering, the Company
will indemnify such Underwriters, each Person who controls such Underwriters
(within the meaning of Section 15 of the Securities Act or Section 20 of the
Securities Exchange Act) and their respective officers, directors, partners,
employees, agents and representatives to the same extent as provided above with
respect to the indemnification of the Holders of Registrable Securities.

                  8(b) Indemnification by Holders. In connection with any
registration statement in which Holders of Registrable Securities are
participating, each such Holder will furnish to the Company in writing such
information as the Company reasonably requests for use in connection with any
such registration statement or prospectus and, to the extent permitted by law,
will indemnify the Company, each Person who controls the Company (within the
meaning of Section 15 of the Securities Act or Section 20 of the Exchange Act)
and their respective officers, directors, partners, employees, agents and
representatives against any Losses arising out of or based upon any untrue or
alleged untrue statement of a material fact contained in any registration

statement, prospectus, or form of prospectus, or arising out of or based upon
any omission or alleged omission of a material fact required to be stated
therein or necessary to make the statements therein, in light of the
circumstances under which made, not misleading, to the extent, but only to the
extent, that such untrue or alleged untrue statement is contained in, or such
omission or alleged omission is required to be contained in, any information so
furnished in writing by such Holder to the Company expressly for use in such
registration statement or prospectus and that such statement or omission was
relied upon by the Company in preparation of such registration statement,
prospectus or form of prospectus; provided, however, that such Holder of
Registrable Securities shall not be liable in any such case to the extent that
the Holder has furnished in writing to the Company prior to the filing of any
such registration statement or prospectus or amendment or supplement thereto
information expressly for use in such registration statement or prospectus or
any amendment or supplement thereto which corrected or made not misleading,
information previously furnished to the Company, and the Company failed to
include such information therein. In no event shall the liability of any selling
Holder of Registrable Securities hereunder be greater in amount than the dollar
amount of the proceeds (net of payment of all expenses) received by such Holder
upon the sale of the Registrable

                                      -17-

<PAGE>



Securities giving rise to such indemnification obligation. Such indemnity shall
remain in full force and effect regardless of any investigation made by or on
behalf of such indemnified party.

                  8(c) Conduct of Indemnification Proceedings. If any Person
shall be entitled to indemnity hereunder such indemnified party shall give
prompt notice to the party or parties from which such indemnity is sought of the
commencement of any Proceeding with respect to which such indemnified party
seeks indemnification or contribution pursuant hereto; provided, however, that
the failure to so notify the indemnifying parties shall not relieve the
indemnifying parties from any obligation or liability except to the extent that
the indemnifying parties have been prejudiced by such failure. The indemnifying
parties shall have the right, exercisable by giving written notice to an
indemnified party promptly after the receipt of written notice from such
indemnified party of such Proceeding, to assume, at the indemnifying parties'
expense, the defense of any such Proceeding, with counsel reasonably
satisfactory to such indemnified party; provided, however, that an indemnified
party or parties (if more than one such indemnified party is named in any
Proceeding) shall have the right to employ separate counsel in any such
Proceeding and to participate in the defense thereof, but the fees and expenses
of such counsel shall be at the expense of such indemnified party or parties
unless the parties to such Proceeding include both the indemnified party or
parties and the indemnifying party or parties, and there exists, in the opinion
of the parties' counsel, a conflict between one or more indemnifying parties and
one or more indemnified parties, in which case the indemnifying parties shall,
in connection with any one such Proceeding or separate but substantially similar
or related Proceedings in the same jurisdiction, arising out of the same general

allegations or circumstances, be liable for the fees and expenses of not more
than one separate firm of attorneys (together with appropriate local counsel) at
any time for such indemnified party or parties. If an indemnifying party assumes
the defense of such Proceeding, the indemnifying, parties will not be subject to
any liability for any settlement made by the indemnified party without its or
their consent (such consent not to be unreasonably withheld).

                  8(d) Contribution. If the indemnification provided for in this
Section 8 is unavailable to an indemnified party or is insufficient to hold such
indemnified party harmless for any Losses in respect of which this Section 8
would otherwise apply by its terms, then each applicable indemnifying party, in
lieu of indemnifying such indemnified party, shall have an obligation to
contribute to the amount paid or payable by such indemnified party as a result
of such Losses, in such proportion as is appropriate to reflect the relative
fault of the indemnifying party, on the one hand, and such indemnified party, on
the other hand, in connection with the actions, statements or omissions that
resulted in such Losses as well as any other relevant equitable considerations.
The relative fault of such indemnifying party, on the one hand, and indemnified
party, on the other hand, shall be determined by reference to, among other
things, whether any action in question, including any untrue or alleged untrue
statement of a material fact or omission or alleged omission to state a material
fact, has been taken by, or relates to information supplied by, such
indemnifying party or indemnified party, and the parties' relative intent,
knowledge, access to information and opportunity to correct or prevent any such
action, statement or omission. The amount paid or payable by a party as a result
of any Losses shall be deemed to include any legal or other fees or expenses
incurred by such party in connection

                                      -18-

<PAGE>



with any Proceeding, to the extent such party would have been indemnified for
such expenses under Section 8(c), if the indemnification provided for in Section
8(a) or Section 8(b) was available to such party. The parties hereto agree that
it would not be just and equitable if contribution pursuant to this Section 8(d)
were determined by pro rata allocation or by any other method of allocation that
does not take account of the equitable considerations referred to in the
immediately preceding paragraph. Notwithstanding the provisions of this Section
8(d), an indemnifying party that is a selling Holder of Registrable Securities
shall not be required to contribute any amount in excess of the amount by which
the net proceeds received by such indemnifying party exceeds the amount of any
damages that such indemnifying party has otherwise been required to pay by
reason of such untrue or alleged untrue statement or omission or alleged
omission. No person adjudged guilty of fraudulent misrepresentation (within the
meaning of Section 11(f) of the Securities Act) shall be entitled to
contribution from any Person who was not guilty of such fraudulent
misrepresentation.

         9.       Miscellaneous.

                  9(a) Amendments and Waivers. The provisions of this Agreement,

including the provisions of this sentence, may not be amended, modified or
supplemented, and waivers or consents to departures from the provisions hereof
may not be given unless the Company has obtained the written consent of the
Holders of a majority of the Registrable Securities; provided, however, that no
amendment, modification or supplement or waiver or consent to the departure with
respect to the provisions of Section 2, Section 3, Section 4, Section 7, or
Section 8 hereof shall be effective as against any Holder of Registrable
Securities unless consented to in writing by such Holder of Registrable
Securities.

                  9(b) Notices. All notices and other communications provided
for or permitted hereunder shall be made in writing by hand-delivery, registered
first-class mail, telex, telecopier, or any courier guaranteeing overnight
delivery (i) if to a Holder, at the most current address given by such Holder to
the Company by means of a notice given in accordance with the provisions of this
Section 9(b) (ii) if to the Company, at 2440 Research Boulevard, Suite 400,
Rockville, MD 20850, Attention: General Counsel, and thereafter at such other
address, notice of which is given in accordance with the provisions of this
Section 9(b).

         All such notices and communications shall be deemed to have been duly
given: at the time delivered by hand, if personally delivered; five business
days after being deposited in the mail, postage prepaid, if mailed; when
answered back, if telexed; when receipt is acknowledged, if telecopied; and on
the next business day if timely delivered to an air courier guaranteeing
overnight delivery.

                  9(c) Successors and Assigns. This Agreement shall inure to the
benefit of and be binding upon the successors, assigns and transferees of each
of the parties, including, without limitation and without the need for an
express assignment, subsequent Holders. If any successor, assignee or transferee
of any Holder shall acquire Registrable Securities, in any manner, whether by
operation of law or otherwise, such Registrable Securities shall be held

                                      -19-

<PAGE>



subject to the terms of this Agreement, and by taking and holding such
Registrable Securities such Person shall be entitled to receive the benefits
hereof and shall be conclusively deemed to have agreed to be bound by all of the
terms and provisions hereof. Notwithstanding the foregoing, only Matra, as a
Holder of Registrable Securities, may request an Underwritten Offering pursuant
to Section 3(a) with respect to Registrable Securities with a Market Value, as
of the date of such request, of less than $20 million.

                  9(d) Counterparts. This Agreement may be executed in any
number of counterparts and by the parties hereto in, separate counterparts, each
of which when so executed shall be deemed to be an original and all of which
taken together shall constitute one and the same agreement.

                  9(e) Headings. The headings in this Agreement are for

convenience of reference only and shall not limit or otherwise affect the
meaning hereof.

                  9(f) Governing Law; Consent to Jurisdiction. THIS AGREEMENT
AND THE DUTIES AND OBLIGATIONS OF THE PARTIES HERETO SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE INTERNAL LAWS OF THE STATE OF NEW YORK, WITHOUT
GIVING EFFECT TO THE CONFLICTS OF LAW PROVISIONS THEREOF. EACH OF THE PARTIES
HERETO AGREES TO SUBMIT TO THE NON-EXCLUSIVE JURISDICTION OF THE COURTS OF THE
STATE OF NEW YORK IN ANY ACTION OR PROCEEDING ARISING OUT OF OR RELATING TO THIS
AGREEMENT.

                  9(g) Severability. In the event that any one or more of the
provisions contained herein, or the application thereof in any circumstance, is
held invalid, illegal or unenforceable, the validity, legality and
enforceability of any such provision in every other respect and of the remaining
provisions contained herein shall not be affected or impaired thereby.

                  9(h) Specific Performance. The parties hereto acknowledge that
there would be no adequate remedy at law if any party fails to perform any of
its obligations hereunder, and accordingly agree that each party, in addition to
any other remedy to which it may be entitled at law or in equity, shall be
entitled to compel specific performance of the obligations of any other party
under this Agreement in accordance with the terms and conditions of this
Agreement in any court of the United States of America or any State thereof
having jurisdiction.

                  9(i) Entire Agreement. This Agreement is intended by the
parties as a final expression of their agreement and intended to be a complete
and exclusive statement of the agreement and understanding of the parties hereto
in respect of the subject matter contained herein. This Agreement supersedes an
prior oral or written agreements, commitments or understandings between the
parties with respect to the matters provided for herein.


                                      -20-

<PAGE>


         IN WITNESS WHEREOF, the parties have executed this Agreement as of the
date first written above.

                                    ORION NETWORK SYSTEMS, INC.


                                    By: /s/ Richard H. Shay
                                        -----------------------------
                                        Name: Richard H. Shay
                                        Title: Vice President / Secretary


                                    BRITISH AEROSPACE HOLDINGS, INC.


                                    By: /s/ Charles E. Gaba
                                        -------------------------------
                                        Name: Charles E. Gaba
                                        Title: Vice President


                                    MATRA MARCONI SPACE UK LIMITED


                                    By: /s/ J. Gail Bancroft
                                        -------------------------------
                                        Name: J. Gail Bancroft
                                        Title: Attorney-in-fact



                                      -21-


<PAGE>

                                                                      EXHIBIT 4

                               EXCHANGE AGREEMENT


                  THIS EXCHANGE AGREEMENT (this "Agreement") is entered into as
of January 8, 1997, between and among Orion Network Systems, Inc., a Delaware
corporation ("ONS"), and British Aerospace Satellite Investments, Inc., a
Delaware corporation ("BASpace").

                  WHEREAS, ONS wishes to acquire, in exchange for shares of
common stock, par value $.01 per share, of ONS ("ONS Common Stock"), the
remaining shares of common stock ("APSC Common Stock"), par value $.01 per
share, of Asia Pacific Space and Communications, Ltd., a Delaware corporation
("APSC"), not presently owned by ONS, all of which shares of APSC Common Stock
are held by BASpace;

                  WHEREAS, BASpace wishes to transfer its shares of APSC Common
Stock to ONS in exchange for shares of ONS Common Stock; and

                  WHEREAS, the exchange is intended to qualify as a tax free
reorganization pursuant to Section 368(a)(1)(B) of the Internal Revenue Code of
1986, as amended (the "Code");

                  NOW, THEREFORE, in consideration of the foregoing and of the
mutual covenants and agreements hereinafter set forth, the parties hereto hereby
agree as follows:


1.                EXCHANGE OF SHARES

                  On the basis of the representations, warranties and agreements
contained herein, and subject to the terms and conditions hereof, BASpace hereby
agrees to transfer to ONS at the Closing (as defined below) the 422,347 shares
of APSC Common Stock held by it (the "BASpace APSC Shares") in exchange for
85,715 shares of ONS Common Stock (the "ONS New Shares").


2.                REPRESENTATIONS AND WARRANTIES OF BASPACE

                  BASpace hereby represents and warrants to ONS as follows:

                  2.1. Title to APSC Common Stock. BASpace is, and on the
Closing Date (as defined below) will be, the lawful owner of the BASpace APSC
Shares. BASpace has, and on the Closing Date BASpace will have, good, valid and
marketable title, free and clear of any mortgage, lien, pledge, encumbrance,
security interest, deed of trust, option, encroachment, reservation, order,
decree, judgment, condition, restriction, charge, agreement, claim or equity of
any kind ("Encumbrances"), to the BASpace APSC Shares, with full right and
lawful authority to transfer the BASpace APSC Shares to ONS pursuant to this
Agreement.



<PAGE>



                  2.2. Organization and Standing; Capacity. BASpace is a
corporation duly organized, validly existing and in good standing under the laws
of its jurisdiction, and has the full corporate power and authority to carry on
its business as currently conducted. BASpace has full legal right, capacity,
power and authority (corporate or otherwise) to execute and deliver this
Agreement and to consummate the transactions contemplated hereby.

                  2.3. Authorization. The execution, delivery and performance by
BASpace of this Agreement and all other documents contemplated hereby, the
fulfillment of and the compliance with the respective terms and provisions
hereof and thereof, and the consummation of the transactions contemplated hereby
and thereby have been duly authorized by all necessary corporate action of
BASpace (which authorization has not been modified or rescinded and is in full
force and effect), and will not: (a) conflict with, or materially violate any
provision of, any law having applicability to BASpace or any person or entity
under common control (an "Affiliate") with BASpace which is a party to any
agreement with or relating to ONS or any term or provision of the articles of
incorporation or organization, or bylaws or operating agreement of BASpace or
any of such Affiliates, as applicable; or (b) conflict with, or result in any
material breach of, or constitute a material default under, any agreement to
which BASpace or any of such Affiliates is a party or by which BASpace or any of
such Affiliates may be bound.

                  2.4. Restrictions and Consents. There are no agreements, laws
or other restrictions of any kind to which BASpace is party or subject that
would prevent or restrict the execution, delivery or performance of this
Agreement.

                  2.5. Binding Obligation. This Agreement constitutes a valid
and binding obligation of BASpace, enforceable in accordance with its terms.
Each document to be executed by BASpace pursuant hereto, when executed and
delivered in accordance with the provisions hereof, will be a valid and binding
obligation of BASpace, enforceable in accordance with its terms.

                  2.6. Transfer of Title. At the Closing, ONS will acquire good,
valid and marketable title to the BASpace APSC Shares, free and clear of all
Encumbrances, other than restrictions on resale contained in federal and state
securities laws.

                  2.7. Accredited Investors. BASpace is an "accredited investor"
as such term is defined in Rule 501 of the Securities Act of 1933, as amended,
and all laws promulgated pursuant thereto or in connection therewith (the
"Securities Act").


3.                REPRESENTATIONS AND WARRANTIES OF ONS

                  ONS hereby represents and warrants to BASpace as follows:


                  3.1. Organization and Standing. ONS is a corporation duly
organized, validly existing and in good standing under the laws of the State of
Delaware, and has


<PAGE>


the full corporate power and authority to carry on its business as currently
conducted. ONS has the full legal right, capacity, power and authority
(corporate or otherwise) to execute and deliver this Agreement and the other
documents called for herein and to consummate the transactions contemplated
hereby. ONS is qualified as a foreign corporation in the State of Maryland, and
in every other jurisdiction in which the failure to so qualify would have a
material adverse effect on the business, results of operations, liabilities,
properties, assets or financial condition of ONS and its subsidiaries, taken as
a whole, or a material adverse effect on the transactions contemplated by this
Agreement.

                  3.2. Authorization. The execution, delivery and performance by
ONS of this Agreement and the other documents contemplated hereby, the
fulfillment of and the compliance with the respective terms and provisions
hereof and thereof, and the consummation of the transactions contemplated hereby
and thereby have been duly authorized by all necessary corporate action of ONS
(which authorization has not been modified or rescinded and is in full force and
effect), and will not: (a) conflict with, or materially violate any provision
of, any law having applicability to ONS or any of its Affiliates or any term or
provision of the articles of incorporation or organization, or bylaws or
operating agreement of ONS, as applicable; or (b) conflict with, or result in
any material breach of, or constitute a material default under, any agreement to
which ONS or any of its Affiliates is a party or by which ONS or any of its
Affiliates may be bound.

                  3.3. Restrictions and Consents. There are no agreements, laws
or other restrictions of any kind to which ONS is a party or subject that would
prevent or restrict the execution, delivery or performance of this Agreement.

                  3.4. Binding Obligation. This Agreement constitutes a valid
and binding obligation of ONS, enforceable in accordance with its terms. Each
document to be executed by ONS pursuant hereto, when executed and delivered in
accordance with the provisions hereof, will be a valid and binding obligation of
ONS, enforceable in accordance with its terms.

                  3.5. Issuance of Shares. Upon consummation of the transactions
contemplated by this Agreement at Closing, the ONS New Shares will be duly and
validly issued, fully paid and nonassessable and no personal liability attaches
to the ownership thereof, and BASpace will acquire the legal, valid and
marketable title to the ONS New Shares, free and clear of all Encumbrances.

                  3.6. Capitalization. As of the date hereof, the authorized
capital stock of ONS consists of 40,000,000 shares of ONS Common Stock and
1,000,000 shares of preferred stock, par value $.01 per share, of which
10,974,121 shares of ONS Common Stock, 13,871 shares of ONS Series A Preferred
Stock and 4,298 shares of ONS Series B Preferred Stock are duly authorized and

validly issued and outstanding, fully paid and nonassessable. ONS has no other
class of stock authorized or outstanding. Options and warrants to purchase
948,074 shares of ONS Common Stock are outstanding on the date hereof, and when
such options are exercised and the prescribed exercise price paid, the shares of
ONS Common Stock issued with respect to such options will be duly


<PAGE>

authorized, validly issued, fully paid and nonassessable. Options to purchase
351 shares of ONS preferred stock are outstanding on the date hereof, the terms
of which are to be substantially identical to the ONS Series A Preferred Stock
and the ONS Series B Preferred Stock other than the conversion price. The ONS
New Shares to be issued to BASpace hereunder will not be issued in violation of
any preemptive or other rights of any person, whether arising by statute, under
the Certificate of Incorporation or By-Laws of ONS or in any other manner.


4.                RESTRICTED SECURITIES

                  BASpace hereby severally represents, warrants and covenants to
ONS as follows:

                  4.1. No Registration Under the Securities Act. BASpace
understands that the ONS New Shares to be acquired by it under this Agreement
have not been registered under the Securities Act, in reliance upon exemptions
contained in the Securities Act or interpretations thereof, and cannot be
offered for sale, sold or otherwise transferred unless subsequently so
registered or qualify for exemption from registration under the Securities Act.
The ONS New Shares will not be offered for sale, sold or otherwise transferred
by BASpace without either registration or exemption from registration under the
Securities Act.

                  4.2. Acquisition for Investment. The ONS New Shares being
acquired under this Agreement by BASpace are being acquired in good faith solely
for BASpace's own account, for investment and not with a view toward
distribution within the meaning of the Securities Act. BASpace has, and at the
time of Closing BASpace will have, no present plan or intention to sell or
otherwise dispose of the ONS New Shares being acquired under this Agreement
provided, however, that BASpace may decide, from time to time, to sell some or
all of such stock based upon a change in the investment policy of BASpace.

                  4.3. Evaluation of Merits and Risks of Investment. BASpace has
such knowledge and experience in financial and business matters that BASpace is
capable of evaluating the merits and risks of its investment in the ONS New
Shares being acquired hereunder. BASpace understands and is able to bear any
economic risks associated with such investment (including, without limitation,
the necessity of holding the ONS New Shares for an indefinite period of time,
inasmuch as the ONS New Shares have not been registered under the Securities
Act).

                  4.4. Review of Documents. BASpace and its advisers, if any,
have received, and have had a reasonable opportunity to review, the following
documents (collectively, the "Disclosure Materials"): (i) Annual Report on Form

10-K for ONS for the fiscal year ended December 31, 1995; (ii) Quarterly Reports
on Form 10-Q for ONS for the fiscal quarters ended March 31, June 30, and
September 30, 1996; and (iii) Proxy Statement of ONS relating to the Annual
Meeting of Stockholders held on May 23, 1996.


<PAGE>


                  4.5. Opportunity to Request Information. BASpace and its
advisers, if any, have had a reasonable opportunity to ask questions of and
receive information and answers from a person or persons acting on behalf of ONS
concerning the transactions contemplated by this Agreement and all such
questions have been answered and all such information has been provided to their
full satisfaction. In making their investment, BASpace will be relying solely on
their review of the Disclosure Materials (other than any projections included
therein, which are not being relied upon), the representations and warranties
set forth herein, and the documents made available for inspection and the
answers to questions referred to in this Section.


5.                CONDITIONS PRECEDENT TO OBLIGATIONS OF BASPACE

                  The obligations of BASpace under this Agreement are subject to
the fulfillment, at or prior to the Closing, of each of the following
conditions, and failure to satisfy any such condition shall excuse and discharge
all obligations of BASpace to carry out the provisions of this Agreement, unless
such failure is agreed to in writing by BASpace:

                  5.1. Representations and Warranties. The representations and
warranties made by ONS in this Agreement shall be true and complete in all
material respects when made, and on and as of the Closing Date as though such
representations and warranties were made on and as of such date.

                  5.2. Performance. ONS shall have performed and complied in all
material respects with all agreements and covenants required by this Agreement
to be performed or complied with by ONS and prior to the Closing Date.

                  5.3. Documents at Closing. All documents required to be
furnished by ONS to BASpace prior to or at the Closing shall have been so
furnished.

                  5.4. Consents. ONS shall have received all material consents,
authorizations and approvals of governmental, supragovernmental and private
parties which are required to be obtained in order to consummate the
transactions contemplated hereby.


6.                CONDITIONS PRECEDENT TO OBLIGATIONS OF ONS

                  The obligations of ONS under this Agreement are subject to the
fulfillment, at or prior to the Closing, of each of the following conditions,
and failure to satisfy any such condition shall excuse and discharge all
obligations of ONS to carry out the provisions of this Agreement, unless such

failure is agreed to in writing by ONS :

                  6.1. Representations and Warranties. The representations and
warranties made by BASpace in this Agreement shall be true and complete in all
material respects


<PAGE>


when made, and on and as of the Closing Date as though such representations and
warranties were made on and as of such date, except for any changes expressly
permitted by this Agreement.

                  6.2. Performance. BASpace shall have performed and complied
with all material agreements and covenants required by this Agreement to be
performed or complied with prior to the Closing Date.

                  6.3. Documents at Closing. All documents required to be
furnished by BASpace to ONS prior to or at the Closing shall have been so
furnished.

                  6.4. Consents. BASpace shall have received all material
consents, authorizations and approvals of governmental, supragovernmental and
private parties which are required to be obtained in order to consummate the
transactions contemplated hereby.


7.                CLOSING

                  7.1. Closing. Subject to the terms and conditions of this
Agreement, the closing of the exchange of interests (the "Closing") shall take
place at the offices of Hogan & Hartson L.L.P., 555 Thirteenth Street, N.W.,
Washington, D.C. 20004 on such time and date as shall be as proposed by ONS not
more than ten days after satisfaction or waiver of all the conditions specified
in Sections 5 and 6 (the "Closing Date").

                  7.2. Deliveries by BASpace. At the Closing, BASpace shall
deliver to ONS certificates representing the BASpace APSC Shares being issued to
ONS pursuant to Section 1 and such other documents as ONS may reasonably
request.

                  7.3. Deliveries by ONS. At or prior to the Closing, ONS shall
deliver to BASpace certificates representing the ONS New Shares being issued to
BASpace pursuant to Section 1 and such other documents as BASpace may reasonably
request.


8.                SURVIVAL OF REPRESENTATIONS; REMEDIES; RELEASE

                  8.1. Survival of Representations. All representations,
warranties, covenants, indemnities and other agreements made by any party to
this Agreement herein or pursuant hereto shall also be deemed made on and as of
the Closing Date as though such representations, warranties, covenants,

indemnities and other agreements were made on and as of such date, and all such
representations, warranties, covenants, indemnities and other agreements shall
survive the Closing and any investigation, audit or inspection at any time made
by or on behalf of any party hereto, including the review of the Disclosure
Materials.

                  8.2. Specific Performance; No Consequential Damages. In
addition to any other remedies which the parties hereto may have at law or in
equity, the parties


<PAGE>

hereto hereby acknowledge that the APSC Common Stock and the ONS New Shares are
unique, and that the harm to ONS and BASpace resulting from breaches by the
other party of their respective obligations cannot be adequately compensated by
damages. Accordingly, the parties hereto agree that each party shall have the
right to have all obligations, undertakings, agreements, covenants and other
provisions of this Agreement specifically performed by the other parties, and
that the parties hereto shall have the right to obtain an order or decree of
such specific performance in any of the courts of the United States or of any
state or other political subdivision thereof. Notwithstanding any other
provision of this Agreement to the contrary, in no event shall remedies for
breach of this Agreement include a party's incidental or consequential damages.

                  8.3. Release of Claims. Concurrently with the Closing, each of
ONS and BASpace agrees to release and forever discharge the other party and each
of its Affiliates, from and after the Closing, from and against any and all
rights, causes of action, claims, suits, obligations, liabilities, and demands
whatsoever (other than those arising from fraud or misrepresentation), in law or
in equity, whether presently known or unknown, to the fullest extent permitted
by law by reason of, related to, or arising out of any one or more of the
agreements or arrangements that either party may have with APSC (other than this
Agreement).


9.                TERMINATION

                  9.1. Termination. This Agreement may be terminated at any time
before the Closing Date under any one or more of the following circumstances:

                  (a) by the mutual written consent of the parties hereto; or

                  (b) by ONS or BASpace by written notice of termination to the
other parties hereto, if the Closing has not occurred by April 30, 1997;
provided, however, that the terminating party is not in breach of any
obligations or agreements hereunder that are causing any of the conditions
precedent to Closing not to be satisfied.

                  9.2. Effect of Termination. In the event this Agreement is
terminated as provided herein, this Agreement shall forthwith become wholly void
and of no effect, and the parties shall be released from all future obligations
hereunder; provided, however, that the provisions of Section 10.3 relating to
the payment of expenses, shall not be extinguished but shall survive such

termination; provided, further, however, that no party shall be relieved from
its liabilities for breach of representations, warranties, obligations or
agreements prior to termination of this Agreement. The parties hereto shall have
any and all remedies to enforce such obligations provided at law or in equity
(including, without limitation, specific performance).

<PAGE>


10.               MISCELLANEOUS

                  10.1. Additional Actions and Documents. Each of the parties
hereto hereby agrees to take or cause to be taken such further actions, to
execute, deliver and file or cause to be executed, delivered and filed such
further documents, and will obtain such consents, as may be necessary or as may
be reasonably requested in order to fully effectuate the purposes, terms and
conditions of this Agreement.

                  10.2. Broker's Fees and Liabilities. Each party agrees to
indemnify, defend and hold harmless each of the other parties from and against
any and all claims asserted against such parties for any unpaid liability to any
broker, finder or agent for any brokerage fees, finders' fees or commissions,
with respect to the transactions contemplated by this Agreement.

                  10.3. Expenses. Subject to the provisions of Section 10.2,
each party hereto shall pay its own expenses incident to this Agreement and the
transactions contemplated hereunder.

                  10.4. Assignment. BASpace shall have the right to assign its
rights under the Agreement, in whole or in part, to any of its Affiliates or to
designate any of its Affiliates to receive directly the ONS New Shares to be
acquired hereunder (in each case, to the extent permitted by applicable law).
ONS shall have the right to assign its rights under the Agreement, in whole or
in part, to any of its respective Affiliates (to the extent permitted by
applicable law). In no event shall the assignment by ONS or BASpace of its
respective rights under this Agreement, whether before or after the Closing,
release ONS or BASpace from its respective liabilities and obligations
hereunder.

                  10.5. Notices. All notices, demands, requests, or other
communications which may be or are required to be given, served, or sent by any
party to any other party pursuant to this Agreement shall be in writing and
shall be hand delivered, sent by overnight courier or mailed by first-class,
registered or certified mail, return receipt requested, postage prepaid, or
transmitted by telegram, telecopy or telex, addressed as follows:


<PAGE>

                  (i)      If to ONS :

                           2440 Research Boulevard
                           Suite 400
                           Rockville, Maryland  20850

                           Attn:  Richard H. Shay, Esq.

                  (ii)     If to BASpace:

                           British Aerospace
                              Holding, Inc.
                           Washinton Technology Park
                           15000 Conference Center Drive, suite 200
                           Chantilly, Virginia 20151-3819
                           Attn: Charles Gaba, Esq.


Each party may designate by notice in writing a new address to which any notice,
demand, request or communication may thereafter be so given, served or sent.
Each notice, demand, request, or communication which shall be hand delivered,
sent, mailed, telecopied or telexed in the manner described above, or which
shall be delivered to a telegraph company, shall be deemed sufficiently given,
served, sent, received or delivered for all purposes at such time as it is
delivered to the addressee (with the return receipt, the delivery receipt, or
(with respect to a telecopy or telex) the answerback being deemed conclusive,
but not exclusive, evidence of such delivery) or at such time as delivery is
refused by the addressee upon presentation.

                  10.6. Miscellaneous. This Agreement, including the other
documents referred to herein or furnished pursuant hereto constitute the entire
agreement among the parties hereto with respect to the transactions contemplated
herein and therein, and supersede all prior oral or written agreements,
commitments or understandings with respect to the matters provided for herein
and therein. No amendment or modification of this Agreement shall be valid or
binding unless set forth in writing and duly executed and delivered by the party
against whom enforcement is sought. No delay or failure on the part of any party
hereto in exercising any right under this Agreement shall impair any such right
or be construed as a waiver of any default or any acquiescence therein. No
single or partial exercise of any such right shall preclude the further exercise
of such right. No waiver shall be valid against any party hereto unless made in
writing and signed by the party against whom enforcement of such waiver is
sought and then only to the extent expressly specified therein. This Agreement
and the duties and obligations of ONS and BASpace hereunder and under each of
the documents referred to herein shall be enforceable against ONS or BASpace, as
the case may be, in the courts of the United States and of the State of
Delaware. For such purpose, ONS and BASpace hereby irrevocably submit to the
non-exclusive jurisdiction of such courts, and agrees that all claims in respect
of this Agreement and such other documents may be heard and determined in any of
such courts. If any part of any provision of this Agreement or any

<PAGE>

other agreement or document given pursuant to or in connection with this
Agreement shall be invalid or unenforceable in any respect, such part shall be
ineffective to the extent of such invalidity or unenforceability only, without
in any way affecting the remaining parts of such provision or the remaining
provisions of this Agreement. The covenants, undertakings and agreements set
forth in this Agreement shall be solely for the benefit of, and shall be
enforceable only by, the parties hereto and their respective successors, heirs,

executors, administrators, legal representatives and permitted assigns. Subject
to any provisions hereof restricting assignment, this Agreement shall be binding
upon and shall inure to the benefit of the parties hereto and their respective
successors, heirs, executors, administrators, legal representatives and assigns.

                  10.7. Governing Law. This Agreement, the rights and
obligations of the parties hereto, and any claims or disputes relating thereto,
shall be governed by and construed in accordance with the laws of the State of
Delaware (excluding the choice of law rules thereof).

                  10.8. Execution in Counterparts. To facilitate execution, this
Agreement may be executed in as many counterparts as may be required. It shall
not be necessary that the signatures of, or on behalf of, each party, or that
the signatures of all persons required to bind any party, appear on each
counterpart; but it shall be sufficient that the signature of, or on behalf of,
each party, or that the signatures of the persons required to bind any party,
appear on one or more of the counterparts. All counterparts shall collectively
constitute a single agreement. It shall not be necessary in making proof of this
Agreement to produce or account for more than a number of counterparts
containing the respective signatures of, or on behalf of, all of the parties
hereto.

<PAGE>


                  IN WITNESS WHEREOF, the parties hereto have duly executed this
Agreement, or have caused this Agreement to be duly executed on their behalf, as
of the day and year first above written.

                                      ORION NETWORK SYSTEMS, INC.

                                      By: Richard H. Shay
                                          ____________________________

                                          Title: Vice President/Secretary
                                          _______________________________



                                      BRITISH AEROSPACE SATELLITE
                                      INVESTMENTS, INC.


                                      By: Charles E. Gaba
                                          ____________________________

                                      Title: Vice President/Assistant Secretary
                                             __________________________________
                                                


<PAGE>

                                                                      EXHIBIT 8

                                    AGREEMENT


This Contingent Transponder Agreement, dated January 26, 1995, among British
Aerospace Plc, a United Kingdom corporation ("BAe"), Matra Hachette S.A., a
French societe anonyme, and MCN Sat U.S., Inc., a Delaware, U.S.A., corporation
("MCN Sat").


                                   WITNESSETH


WHEREAS, as inducement for Matra S.A., the predecessor of Matra Hachette ("Matra
S.A.") to invest as a limited partner in International Private Satellite
Partners, LP., a Delaware limited partnership, ("IPSP"), BAe agreed to assume
certain contingent transponder liabilities of Matra under a certain IPSP-related
document;

WHEREAS, the basic terms of BAe's agreement were set forth in a letter
agreement, dated 8 October 1990, between British Aerospace Systems, acting on
behalf of BAe, and Matra (the "Letter Agreement");

WHEREAS, as a consequence of, and in reliance upon, BAe's agreement to assume
such contingent transponder obligations, Matra caused its affiliate, MMB, to
commit to invest as a limited partner in IPSP and to execute and deliver certain
IPSP-related documents, including the Amended and Restated Agreement of Limited
Partnership of International Private Satellite Partners, dated as of 25 October
1990, which agreement was subsequently restated and amended (as amended, the
"Partnership Agreement") and Matra executed and delivered to IPSP the Contingent
Communication Satellite Capacity Agreement, dated as of 24 October 1990, which
agreement was subsequently amended (as amended, the "Contingent Agreement");

WHEREAS, pursuant to an Agreement, dated as of 2 April 1992, among IPSP, Matra,
MMB, MCN Sat Services S.A. and MCN Sat, MMB and Matra transferred their
interests in the Partnership Agreement and the Contingent Agreement to MCN Sat
and MCN Sat assumed the obligations of the assignors under said agreements;

WHEREAS, Matra has transferred its rights in and to the Letter Agreement to MCN
Sat; and

WHEREAS, the parties hereto desire to further define the terms of the Letter
Agreement, as is contemplated by Paragraph 5 of said Letter Agreement;

NOW, THEREFORE, in the consideration of MCN's investment in, and continued
support of, IPSP, and for other good and valuable consideration, the receipt of
which is hereby acknowledged, the parties, intending to be legally bound, agree
as follows:




<PAGE>

SECTION 1: PAYMENTS

1.1. Basic Payments. If MCN Sat is required to make a Contingent Payment under
Article II of the Contingent Agreement, BAe shall pay to MCN Sat an amount equal
to 75/175 of the actual amount of such Contingent Payment paid by MCN Sat to
IPSP (the "BAe Portion"), provided that in no month shall the BAe Portion exceed
$153,750, except as provided in Section 1.2 of this Agreement.

1.2. Payment Increases. If the amount of the Contingent Payment MCN Sat is
required to make increases as a result of the completion of phase II financing
(as defined in IPSP Revised Confidential Private Offering Memorandum, dated 17
September 1990), then BAe also shall pay to MCN Sat 75/175 of the amount of such
increase and the term BAe Portion shall be deemed to include the Basic Payment
payable under Section 1.1 hereof and the amount of such increase.

1.3. Timing of Payment. BAe shall remit the BAe Portion to MCN Sat within five
days of its receipt of a notice from MCN. BAe shall make such remission by check
or by wire transfer, as specified in MCN Sat's notice to BAe.

1.4. Late Payments. If BAe fails to pay the BAe Portion to MCN Sat when due,
then BAe shall pay to MCN Sat interest at the rate of 1% per month, compounded
monthly, on the unpaid BAe Portion from the date the BAe Portion is required to
be paid to the date of payment.

1.5. Reimbursement. Within five days of MCN Sat's receipt from IPSP of any
distribution pursuant to Sections 6.04(a)(i) or 6.05(a)(A) of the Partnership
Agreement (each a "Contingent Payment Distribution"), MCN Sat shall pay to BAe
75/175 of such Contingent Payment Distribution, provided that the sum of all
such payments to BAe shall not exceed in the aggregate the sum of all BAe
Portions paid by BAe to MCN Sat pursuant to Sections 1.1 and 1.2 of this
Agreement.


SECTION 2: PURCHASE OF COMMUNICATIONS SATELLITE SERVICES

2.1. Right to Purchase. At any time that BAe is required to make a BAe Portion
payment to MCN Sat, BAe may elect to satisfy its payment obligation through the
purchase of Communications Satellite Services pursuant to Article IV of the
Contingent Agreement.

2.2. Service Election Notice. Within five days of MCN Sat's receipt of a notice
from BAe stating its desire to purchase Communications Satellite Services in
lieu of making payments of the BAe Portion to MCN Sat, which notice shall
contain such information as Section 4.01 of the Contingent Agreement requires to
be contained in a Service Election Notice, MCN Sat shall deliver to IPSP a
Service Election Notice pursuant to Section 4.01.

2.3. IPSP Communications. MCN Sat shall notify BAe promptly upon its receipt
from IPSP of any Service Provision Notice (as defined in the Contingent
Agreement) or of any other

                                        2


<PAGE>



communication received from IPSP with respect to the Communications Satellite
Services purchased or to be purchased by BAe.

2.4. Limitation of MCN Sat's Obligation to Provide Services. Notwithstanding
Sections 2.1., 2.2., and 2.3. MCN Sat shall be obligated to provide
Communications Satellite Services to BAe only to the extent that IPSP provides
the same to MCN Sat and MCN Sat shall have no liability whatsoever to BAe if
IPSP fails to deliver Communications Satellite Services to MCN Sat (or directly
to BAe at MCN Sat's request) or reduces the scope of level of such Services.

2.5. Compliance with Contingent Agreement. BAe shall comply with, shall not take
any action that would cause MCN Sat to violate, and shall not fail to take any
action required to be taken by a user of Communications Satellite Services under
Sections 7.03(a), 7.03(b), 7.03(c), and 10.1 of the Contingent Agreement. If, as
a result of BAe's actions or use of Communications Satellite Services, IPSP
alleges that MCN Sat is in default under the Contingent Agreement, then BAe, at
its own cost, shall participate in MCN Sat's defense. If MCN Sat is determined
to be in default under the Contingent Agreement due to a violation of Section
7.03(a), 7.03(b), 7.03(c) or 10.1 with respect to the Communications Satellite
Services sold to BAe, then BAe shall reimburse MCN Sat for all damages resulting
from such violation and all costs and expenses incurred by MCN Sat in defending
against any action on the default.

2.6. Timing of Payments. Within five days of BAe's receipt from MCN Sat of an
invoice, BAe shall remit to MCN Sat the amount specified on such invoice (the
"Purchase Price"). BAe shall make such remission by check or wire transfer as
specified in MCN Sat's invoice to BAe.

2.7. Late Payments. If BAe fails to pay the Purchase Price when due, then BAe
shall pay to MCN Sat interest at the rate of 1% per month, compounded monthly,
on the unpaid Purchase Price from the date the Purchase Price is required to be
paid to the date of payment.


SECTION 3: OPTION AGREEMENT

3.1. Expiration of Option. The time for MCN Sat's right to exercise its option
under the Option Agreement, dated as of 24 December 1991, between MCN Sat and
IPSP (the "Option Agreement"), having expired, BAe hereby acknowledges that it
has waived all rights to direct MCN Sat to exercise such option. If, however,
the Option Agreement is reinstated, then BAe shall have the right to direct MCN
Sat to exercise its rights to receive capacity under the Option Agreement on any
satellite for which funds may be drawn under the Contingent Agreement.

3.2. Payment for Option Capacity. Within five days of BAe's receipt from MCN Sat
of an invoice in the form attached as Exhibit 3.2. BAe shall remit to MCN Sat
the amount specified on such invoice (the "Option Capacity Price"). BAe shall
make such remission by check or wire transfer, as specified in MCN Sat's invoice
to BAe.



                                        3

<PAGE>



3.3. Late Payments. If BAe fails to pay the Option Capacity Price when due, then
BAe shall pay to MCN Sat interest at the rate of 1% per month, compounded
monthly on the unpaid Option Capacity Price from the date the Option Capacity
Price is required to be made to the date of payment.


SECTION 4: MATRA HACHETTE GUARANTEE

Matra Hachette hereby guarantees the payment and performance obligations of MCN
Sat hereunder.


SECTION 5: MISCELLANEOUS

5.1.     Entire Agreement

5.1.1. This instrument contains all of the understanding and agreements of every
kind and nature existing between the parties hereto with respect to the subject
matter of this Agreement.

5.1.2. All exhibits that are referred to herein and attached hereto shall be
considered a part of this agreement.

5.1.3. Numbered or lettered articles, sections, and subsections herein contained
refer to articles, sections, and subsections of this Agreement unless otherwise
expressly stated.

5.1.4. All headings herein are inserted only for convenience and ease of
reference and are not to be considered in the construction or interpretation of
any provision of this Agreement.

5.2. Severability. If any provision of this Agreement or the application of such
provision to any person or circumstance is held to be invalid or unenforceable,
the remainder of this Agreement and the application of such provision to the
person or circumstance, other than those in respect of which it is invalid or
unenforceable, shall not be affected thereby except those provisions that are
made subject to or conditioned upon such invalid or unenforceable provisions.

5.3. Language. The language used in this Agreement shall be deemed to be the
language chosen by the parties to express their mutual intent, and no rule of
strict construction shall be applied against any party.

5.4. Waiver. No party's consent to, or express or implied waiver of, any breach
or default by the other party in the performance by such other party of its
obligations hereunder shall be deemed or construed to be a consent to or waiver
of any other breach of default in the performance by such other party of the

same or any other obligations of such party hereunder. A party's failure to
complain of any act or failure to act of any of the other party or to declare

                                        4

<PAGE>



the other party in default, irrespective of how long such failure continues,
shall not constitute a waiver by such party or its rights hereunder.

5.5.   Benefits.

5.5.1. Subject to the restrictions on transfers and encumbrances set forth
herein, this Agreement shall inure to the benefit of and be binding upon the
undersigned parties and their respective successors and assigns. Whenever a
reference to any party is made in this Agreement, such reference shall be deemed
to include a reference to the successors and assigns of such party.

5.5.2. The provisions of this Agreement are not intended to be for the benefit
of any third party on whom benefits are not specifically conferred by this
Agreement.

5.6.   Amendments; Assignments

5.6.1. This Agreement may not be amended, altered, or modified except by a
written instrument signed by the parties.

5.6.2. This Agreement shall not be assigned by either party without the prior
written consent of the other, except that BAe may assign its rights and
obligations hereunder to any entity then constituting a corporate member of the
BAe Group ("a BAe Group member") provided that BAe either remains liable
hereunder or guarantees, as a primary obligor, the payment and performance
obligations of such BAe Group Member hereunder.

5.7. Counterparts. This Agreement may be executed in a number of counterparts,
each of which shall be deemed an original and all of which shall constitute one
and the same instrument.

5.8. Jurisdiction; Service of Process

5.8.1. Any action or proceeding seeking to enforce any provisions of, or based
on any right arising out of, this Agreement may be brought against the parties
only in the courts of the State of New York or, if jurisdiction may be acquired,
in the federal courts of New York and each of the parties hereby consents to the
jurisdiction of such courts (and of the appropriate appellate courts) in any
such action or proceeding and waives any obligation to venue laid therein.

5.8.2. Process in any action or proceeding referred to in Section 5.8.1. may be
served on any party anywhere in the world, whether within or without the State
of New York, without regard to any geographical limits on service of process
that may be imposed by the courts referred to in Section 5.8.1.


5.9. Payments. All payments required to be made hereunder shall be made in legal
tender of the United States of America.


                                        5

<PAGE>



5.10. Notices: Demands: Requests: Payments

5.10.1. All notices, demands, or requests required or permitted to be given
pursuant to this Agreement must be in writing.

5.10.2. All notices, demands, and requests required or permitted to be given
hereunder shall be deemed to have been properly given if served personally or if
sent by telecopy, by registered or certified airmail, postage prepaid, or by
overnight courier, addressed as follows:

To MCN Sat:                MCN Sat U.S. Inc.
                           4, rue de Presbourg
                           75116 Paris
                           France

                           Attention:       George PAYET
                           Telephone:       (33.1) 34.88.41.05
                           Telefax:         (33.1) 34.88.48.88

To BAe:                    British Aerospace Plc
                           Warwick House
                           P.O. Box 87
                           Farnborough Aerospace Center
                           Farnborough
                           Hants GU14 6YU

                           Attention:        M. Walker
                           Telephone:       (44) 252.38.3879
                           Telefax:         (44) 252.38.3421

or such other addresses as shall be furnished by like notice by such party. Any
notice or communication given by mail shall be deemed to have been received
seven days after deposit in the mails; any notice or communication given by
overnight courier shall be deemed to have been received two days after delivery
of the notice to such courier; and any notice or communication given by telecopy
shall be deemed to have been received when sent by telecopy and mechanical
acknowledgement of receipt or oral acknowledgment by the addressee is received.

5.10.3. The time period in which a response to any such notice, demand, or
request must be given shall comment to run from the date of delivery if served
or delivered in person, the date of receipt on the return receipt of the notice,
demand, or request by the addressee thereof in the case of the mails and
overnight courier, and from the date receipt is mechanically or orally
acknowledged in the case of a telecopy.



                                        6

<PAGE>


5.11. Governing Law. This Agreement and the obligations of the parties hereunder
shall be interpreted, construed and enforced in accordance with the laws of the
State of New York.

IN WITNESS WHEREOF, the parties hereto have executed this Agreement, as of the
day and year first above written.



For an on behalf of:                       For and on behalf of:
Matra Hachette                             MCN Sat U.S., Inc.


/s/ illegible                              /s/ Claude Goumy
By:[Illegible]                             By:  Claude Goumy   CEO



For  and on behalf of:
British Aerospace Plc


/s/ D. Parkes
By: D. Parkes


                                        7


<PAGE>


[Letterhead of British Aerospace]



23rd December 1996


Mr. C. Goumy,
MCN Sat US Inc. and Lagardere Groupe SA
37 avenue Louis Breguet - BPI,
78146 Velizy-Villacoublay Cedex,
FRANCE


Dear Sir:

We refer to the Contingent Transponder Agreement dated 26th January 1995, among
British Aerospace Plc ("BAe"), MCN Sat US, Inc. ("MCN"), and Lagardere Groupe,
being the successor to Matra Hachette SA (the "Indemnity Agreement") pursuant to
which BAe agreed to indemnify MCN for 75/175 of the actual amount paid by MCN to
International Private Satellite Partners, LP ("IPSP") under that certain
Contingent Communications Satellite Capacity Agreement, dated as of 24th October
1990, between MCN and IPSP (the "Contingent Capacity Agreement"). Each of the
payments made by BAe to MCN under the Indemnity Agreement is herein called a
"BAe Portion". As of the date hereof BAe has paid $2,252,143 to MCN pursuant to
the Indemnity Agreement. Capitalized words used herein and not defined shall
have the meanings attributed to them in the Indemnity Agreement.

Under Section 1.5 of the Indemnity Agreement, within five days of each date upon
which MCN receives a Contingent Payment Distribution from IPSP, MCN is required
to pay to BAe 75/175 of such Contingent Payment Distribution until the sum of
all such payments made by MCN to BAe equals the sum of all BAe Portions paid by
BAe to MCN under Sections 1.1 and 1.2 of the Indemnity Agreement.

Pursuant to the Section 351 Exchange Agreement and Plan of Conversion dated June
1996 as amended by the First Amendment thereto among IPSP, Orion Network
Systems, Inc. ("ONS"), Orion Satellite Corporation, British Aerospace
Communications Inc. ("BAeComs"), Com Dev Satellite Communications Limited,
Kingston Communications International Limited, Lockheed Martin Commercial Launch
Services Inc., Trans-Atlantic Satellite, Inc. and MCN (the "Exchange
Agreement"), an affiliate of ONS ("Orion") is proposing to issue shares of its
Series C 6% Cumulative Redeemable Convertible Preferred Stock (the "Preferred
Stock") to each of the IPSP limited partners (other than ONS) and to release
each of the limited partners from such limited partner's obligations under its
Contingent Capacity Agreement, among others, in exchange for such limited
partner's limited partnership shares in IPSP (the "Exchange Transaction"). A
portion of the number of shares of Preferred Stock to be delivered to each of


<PAGE>



                                        2

the limited partners in the Exchange Transaction represents repayment by ONS, on
behalf of IPSP, of the amounts paid by the limited partners to IPSP under their
Contingent Capacity Agreements.

In the consideration of the premises set forth herein and for other good and
valuable consideration, the receipt of which is acknowledged, the parties,
intending to be legally bound, agree as follows:

1.       (i) In respect of BAe Portions paid on or before 29th January, 1997,
         within five days of the date upon which MCN receives from Orion one or
         more certificates evidencing the shares of Preferred Stock that Orion
         is required to deliver to MCN in the Exchange Transaction (the "Closing
         Date"), MCN shall irrevocably assign to BAeComs, free of all
         encumbrances, (a) 1,914 shares of Preferred Stock in respect of BAe
         Portions prior to 24th December, 1996 plus (b) in respect of all BAe
         Portions made between 24th December, 1996 and 29th January, 1997 a
         number of shares of Preferred Stock equal to the quotient obtained by
         dividing (i) 85% of the aggregate of such BAe Portions by (ii) 1,000 or
         such other number as is used to compute the number of shares MCN will
         be entitled to receive in the Exchange Transaction.

         (ii) In respect of BAe Portions paid in the period from 30th January,
         1997 until Closing, to the extent that MCN receives cash refunds for
         Contingent Capacity Payments under Section 3.2(c)(x) of the Exchange
         Agreement as amended, it will within five days of the receipt pay
         75/175 of that amount to BAe Coms in immediately available funds in US
         dollars. To the extent that MCN receives shares of Preferred Stock, MCN
         shall within five days irrevocably assign to BAeComs, free of all
         encumbrances, 75/175 of the number of shares received. If MCN receives
         a mixture of cash and Preferred Stock, MCN will pay to BAe 75/175 of
         the cash received and irrevocably assign 75/175 of the shares of
         Preferred Stock received.

2.       The Indemnity Agreement shall terminate only upon the date upon which
         MCN's obligations under the Contingent Capacity Agreement terminate.

3.       This Letter Agreement shall be governed by the laws of the State of New
         York without regard to its conflicts of laws principles.

4.       The provisions of this Letter Agreement are not intended to be for the
         benefit of any third party upon whom benefits are not specifically
         conferred by this Agreement.

5.       This Letter Agreement may not be amended, altered or modified except by
         a written instrument signed by the parties.

6.       This Letter Agreement may be executed in a number of counterparts, each
         of which shall be deemed an original and all of which shall constitute
         one and the same instrument.




<PAGE>


                                        3

7.       BAe may terminate this Letter Agreement on 1st May, 1997 if the Closing
         Date has not occurred by such date and BAeComs has served notice of
         termination under Section 13.1(b) of the Exchange Agreement as amended.

8.       MCN may terminate this Letter Agreement on 1st May, 1997 if the Closing
         Date has not occurred by such date and it has served notice of
         termination under Section 13.1(b) of the Exchange Agreement as amended.

9.       This Letter Agreement and the Indemnity Agreement contain all of the
         understanding and agreements of every kind and nature existing between
         BAe and MCN with respect to the subject matter of this Agreement. In
         particular this Letter Agreement supersedes the Letter Agreement
         between us dated 1st July 1996 which shall cease to have effect as from
         signature of this Letter Agreement by all parties to it.

If the terms of this Letter Agreement are satisfactory to you, please so
indicate by signing in the space provided below.

Sincerely                              Accepted and Agreed:



British Aerospace Plc.                 For and on behalf of Lagardere Groupe SA

By  /s/ W.A. Rice                      By /s/ illegible
    -------------                         -------------

Name     W.A. Rice
Title    Director
         BAe Communications

                                       For and on behalf of MCN Sat. US, Inc.

                                       By /s/ Claude Goumy
                                         --------------------

                                       Claude Goumy, President



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