EXECUTION COPY





               This MULTIPARTY AGREEMENT relating to Launch #1 (the "Agreement")
is entered into as of July 22, 1997, among ARIANESPACE S.A., a company organized
under the laws of France ("AE"), ARIANESPACE FINANCE S.A., a company organized
under the laws of Luxembourg ("AEF") and CD Radio Inc., a company organized
under the laws of Delaware (the "Customer" or the "LSA Party").

               WHEREAS, AE and the LSA Party have entered into the Launch
Services Agreement for the purpose of launching the Satellite into Earth orbit;

               WHEREAS, AEF and the Customer have entered into the Customer Loan
Agreement for the purpose of financing certain payments to be made by the LSA
Party to AE under the Launch Services Agreement; and

               WHEREAS, the parties hereto desire to set forth the
interrelationship of certain aspects of the agreements referred to above;

               NOW, THEREFORE, in consideration of the premises and the mutual
agreements, provisions and covenants contained herein, the parties hereto agree
as follows:

               SECTION 1. Defined Terms. Capitalized terms used and not defined
otherwise herein shall have the meanings specified in the Customer Loan
Agreement hereinafter defined. The capitalized terms set forth below shall have
the following meanings:

                       "AE" has the meaning specified in the introductory
        paragraph of this Agreement.

                       "AE Account" means the following bank account as such
        account may be renumbered from time to time or any successor account
        thereto:

                       Credit Lyonnais Luxembourg S.A.
                       Account Number:  036122-43

                       "AEF" has the meaning specified in the introductory
        paragraph of this Agreement.

                       "Customer Loan Agreement" means the Customer Loan
        Agreement dated as of July 22, 1997, between AEF and the Customer,
        relating to Launch # 1.


<PAGE>   2



                       "Financeable Payment" means a payment made or to be made
        under the Launch Services Agreement for any Launch Costs eligible for
        financing under the Customer Loan Agreement, as provided for therein.

                       "Launch Services Agreement" means the Launch Services
        Agreement dated July 22, 1997, between AE and the LSA Party for the
        launch of two satellites, including the Satellite, by Ariane Launch
        Vehicles.

                       "Right of First Refusal" has the meaning specified in
        Section 3(c) hereof.

               SECTION 2. Launch Services Agreement and Customer Loan Agreement
Payment Instructions. (a) AE, AEF and the Customer hereby acknowledge and agree
that (i) the LSA Party shall remain obligated to make all payments to AE at the
times and in the amounts provided pursuant to the Launch Services Agreement,
(ii) notwithstanding anything to the contrary contained in the Launch Services
Agreement, the terms of this Section 2 shall govern the payment of all
Financeable Payments thereunder, (iii) the proceeds of Loans made to the
Customer representing Financeable Payments shall be made directly to the AE
Account as payment under the Launch Services Agreement, as directed pursuant to
the Loan Proceeds Payment Instruction Letter referred to in Section 2(d) hereof,
(iv) disbursement of the proceeds of any Loan to the AE Account shall discharge
any obligation of AEF to disburse the proceeds of such Loan directly to the
Customer under the Customer Loan Agreement, (v) disbursement of the proceeds of
any Loan under the Customer Loan Agreement to the AE Account shall be deemed
payment in full of the corresponding amount of any Financeable Payments in
respect of which such Loan is made and discharge the LSA Party with respect to
its obligations under the Launch Services Agreement for such Financeable
Payments and (vi) if the proceeds of Loans disbursed to the AE Account shall be
less than the aggregate amount of Financeable Payments in respect of which such
Loan is made the LSA Party shall remain obligated to pay the aggregate amount of
Financeable Payments exceeding the amount of such proceeds to AE pursuant to the
Launch Services Agreement.

               (b) AE hereby agrees to invoice the LSA Party for Financeable
Payments pursuant to that section of the Launch Services Agreement governing the
invoicing of such payments, and, if the LSA Party is not the Customer, hereby
agrees to send a copy of each such invoice for Financeable Payments to the
Customer at the address therefor determined pursuant to Section 10 hereof.

               (c) AE hereby agrees, upon the payment of any amount to the AE
Account pursuant to Section 2(a) hereof, to promptly notify the LSA Party of the
date and amount of such payment.

               (d) The Customer hereby agrees to execute and deliver to AEF,
concurrently with the execution of this Agreement, a payment instruction letter
in the form of Exhibit A hereto (the "Loan Proceeds Payment Instruction
Letter").


                                      -2-
<PAGE>   3





               (e) The LSA Party hereby agrees to execute and deliver to AE,
concurrently with the execution of this Agreement, a payment instruction letter
in the form of Exhibit B hereto (the "Launch Services Agreement Payment
Instruction Letter").

               SECTION 3. Financial Termination by LSA Party of the Launch
Services Agreement. (a) Notwithstanding anything to the contrary in the Launch
Services Agreement, if the Customer is unable to procure and maintain sufficient
financing for the Project, and if the LSA Party shall terminate the Launch
Services Agreement in accordance with its terms with respect to the launch
service to which Financeable Payments relate, AE shall be entitled to a
termination fee, depending on the date of termination, as follows:


<TABLE>
<CAPTION>
=====================================================================================================
                                                      Amount to which AE is entitled (expressed
           Date of Termination                      as a percentage of the launch services price)
           -------------------                                         --------------------------
-----------------------------------------------------------------------------------------------------
<S>                                                                      <C>   
Any time prior to L minus (-) six (6) months                              5%
From L minus (-) six (6) months to but not
including L minus (-) three (3) months
                                                                         20%
Any time from and after L minus (-) three
(3) months                                                               40%
=====================================================================================================
</TABLE>

plus (i) any other amount(s) paid or due under the Launch Services Agreement
including, without limitation, postponement fees or late payment interest under
the Launch Services Agreement at the effective date of termination and (ii) the
price of those Associated Services (as defined in the Launch Services Agreement)
provided, at Customer's cost, which have actually been performed as of the
effective date of termination.

               AE shall refund to the LSA Party any amounts paid by the LSA
Party for Launch Costs in excess of the above termination fee, provided that the
right of the LSA Party to receive any such refund from AE shall be subject and
subordinate in right of payment to the prior payment in full of the Customer's
obligations to AEF under the Customer Loan Agreement.

               (b) If, under the terms of the Launch Services Agreement, AE
shall be obligated to pay to the LSA Party any amounts thereunder with respect
to the launch services to which Financeable Payments relate, including but not
limited to the portion thereof referred to in Section 3(a), the LSA Party hereby
irrevocably directs AE to pay such amount to AEF, pursuant to the Launch
Services Agreement Payment Instruction Letter referred to in Section 2(f)
hereof, as a prepayment of amounts outstanding under the Customer Loan
Agreement, to be applied first to interest and other amounts due and outstanding
under the Customer Loan Agreement and then to principal outstanding in inverse
order of maturity. Any remaining balance shall (after deducting therefrom any
costs borne by AEF and resulting from the



                                      -3-
<PAGE>   4


enforcement by AEF of its rights against the Customer under the Customer Loan
Agreement, together with any Break Funding Costs and other amounts due and
owing to AEF under the Customer Loan Agreement) be paid to the LSA Party.

               (c) The LSA Party hereby grants to AE upon the terms and
conditions contained herein, a right of first refusal (the "Right of First
Refusal") with respect to the provision of launch services for the Project in
the event that: (i) the LSA Party shall terminate the Launch Services Agreement
as described in Section 3(a) hereof and (ii) the LSA Party (or any Affiliate
thereof) solicits launch services with respect to the Project from any provider
of launch services other than AE, within two (2) years from such termination.
The LSA Party shall notify AE in writing of its intention to solicit or the
intention of any Affiliate thereof to solicit such launch services promptly
following its decision to do so. Within thirty (30) days of the receipt of such
notification, AE shall notify the Customer whether it wishes to provide launch
services for the Project, and if it offers to do so substantially in accordance
with the terms of the Launch Services Agreement, the Customer shall be obligated
to negotiate in good faith the conclusion of a launch services agreement with
AE.

               SECTION 4. Customer Loan Agreement Event of Default. In
consideration of the fact that AE is receiving funds disbursed by AEF as Loans
pursuant to the terms of the Customer Loan Agreement directly into the AE
Account, if an Event of Default shall occur thereunder, including but not
limited to a failure by the Customer to pay any amount payable by it to AEF
pursuant to Section 2.05(b) thereof on the date when due, AE shall be obligated
to repay to AEF such funds disbursed to it into the AE Account, upon the written
request of AEF. If AE shall become obligated to make any such repayment to AEF,
any Financeable Payments deemed made by such disbursement pursuant to Section
2(a) hereof thereupon shall be deemed not to have been made under the Launch
Services Agreement. In such case, AE shall have the right to immediate payment
of such amounts by the LSA Party and, if such amounts are not so paid, to
exercise any remedies available to it under the Launch Services Agreement
including the right to terminate the Launch Services Agreement with respect to
the launch services for which Financeable Payments relate and, in the event of
termination, shall be entitled to the amounts determined pursuant to that
section thereof governing termination payments with respect to such launch
services immediately upon the occurrence of such Event of Default, whether or
not the Customer is the LSA Party. AEF hereby agrees to promptly notify the LSA
Party (if not the Customer) of the occurrence of any Event of Default under the
Customer Loan Agreement, provided that in no event shall the failure to give
such notice affect any obligation of the LSA Party hereunder or under the Launch
Services Agreement.

               SECTION 5. Reflight. If the LSA Party shall be entitled to but
shall not request a Reflight, with respect to the Launch, within one hundred and
eighty (180) days following the original date of Launch, and a mandatory
prepayment shall become due and payable pursuant to Section 2.05(b) of the
Customer Loan Agreement, the LSA Party and AE hereby agree that the LSA Party
shall be deemed to have exercised its right to request such Reflight, the Launch
Services Agreement shall automatically terminate with respect thereto and AE
shall refund a portion of the Launch Costs to the LSA Party with respect
thereto, as set forth in that section of the Launch Services Agreement governing
termination payments,

                                      -4-
<PAGE>   5


subject to the application of the payment direction set forth in Section 3(b).
If the LSA Party shall be entitled to and shall have requested a Reflight with
respect to the Launch, but then terminate such Reflight, Section 3(a) shall
govern the refund of Launch Costs with respect thereto.

               SECTION 6. ECA Country Risk Coverage. In order to mitigate
certain political risks, AEF and the Lenders may require or the Customer may
request coverage for such risks by the appropriate ECAs. AE, the LSA Party and
the Customer hereby agree to cooperate reasonably to secure such coverage,
including but not limited to, duly completing and filing appropriate requests
and applications in a timely manner, providing any necessary financial,
contractual and other information and negotiating in good faith any amendments
to the Launch Services Agreement, the Customer Loan Agreement and any other
agreement, which may become necessary or desirable as a result of the conditions
for obtaining such coverage.

               SECTION 7. Third Party Liability Insurance. AE shall cause the
Customer, AEF, the Security Agent and the Lenders to be named as additional
insureds under the third party liability insurance procured and maintained by AE
in accordance with the Launch Services Agreement.

               SECTION 8. Delegation. (a) It is hereby agreed that any
undertaking assumed by AE hereunder to make any payment to AEF of sums which are
or shall become due by AE to the LSA Party under the Launch Services Agreement
relating to the Launch, including, without limitation, any such sums referred to
in Section 3(a), 3(b) or 4 hereof, is to be read and construed as an irrevocable
and unconditional "delegation" of AE (as "delegue") by the LSA Party (as
"delegant") for the benefit of AEF (as "delegataire") with the intent that such
"delegation" should take effect as provided in articles 1275 and 1276 of the
French civil code.

               (b) In furtherance of the "delegation" set forth in clause (a) of
this Section 8, AE shall make all payments referred to in such clause (a) in
accordance with the Launch Services Agreement Payment Instruction Letter
referred to in Section 2(e).

               (c) All amounts received by AEF from AE pursuant to the
"delegation" set forth in clause (a) of this Section 8 shall be applied against
any sums due and owing to AEF by the Customer (whether or not the LSA Party)
under the Customer Loan Agreement, and all amounts so paid by AE to AEF shall,
pro tanto, discharge the Customer (whether or not the LSA Party) from the
corresponding payment obligation under the Customer Loan Agreement, in each
case, if more specifically set forth in provisions elsewhere in this Agreement,
in accordance with such provisions. In no event shall AE be required by reason
of this "delegation" to pay at any time to AEF any amount in excess of the
aggregate amounts due and payable at such time by AE to the LSA Party under the
Launch Services Agreement, with respect to the Launch.


                                      -5-
<PAGE>   6


               (d) The "delegation" set forth in clause (a) of this Section 8
shall be deemed to be a "delegation imparfaite" and not a novation, guarantee or
security of the obligations of the LSA Party under the Launch Services Agreement
or the Customer under the Customer Loan Agreement, and each of the LSA Party and
the Customer expressly acknowledge that it shall remain bound to perform such
obligations and that such obligations shall not be modified or altered by reason
of its entering into this "delegation" arrangement.

               SECTION 9. Term. This Agreement shall remain in full force and
effect until the performance in full of the obligations of the parties under the
Launch Services Agreement with respect to the Launch, provided that outstanding
obligations of any party hereto to any other party hereto shall survive the
termination of this Agreement, and provided further that Section 3(c) hereof
shall remain in full force and effect until the expiration of the time periods
set forth therein.

               SECTION 10. Notices. All notices, demands, requests, waivers and
other communications delivered hereunder, whether or not specified to be in
writing, shall be in writing and mailed, delivered or telecopied to the
addresses and telecopier numbers (a) as determined pursuant to the Customer Loan
Agreement, (b) as indicated under the signatures below or (c) to such other
address or telecopier number as shall be designated by any party hereto in a
written notice to the other parties. All such communications shall be effective
when received by the recipient if mailed or delivered and when transmission is
confirmed if by telecopier, provided that any such communications delivered to
AEF by the Customer or the LSA Party (if not the Customer) hereunder or under
any other Loan Document shall be effective only if a copy thereof shall be
delivered to AE in accordance with this Section 10.

               SECTION 11. Entire Agreement; Amendment. This Agreement sets
forth the entire agreement of the parties with respect to the subject matter
hereof. No amendment or waiver of any provision of this Agreement, nor consent
to any departure therefrom by any party shall, in any event be effective unless
the same shall be in writing and signed by all parties, and then such waiver or
consent shall be effective only in the specific instance and for the specific
purpose for which given.

               SECTION 12. Amendment of Launch Services Agreement. In the event
of any inconsistencies between the terms of this Agreement and the Launch
Services Agreement or any supplement to the Launch Services Agreement with
respect to the Launch, the terms of this Agreement shall govern and amend the
Launch Services Agreement pursuant to the section of the Launch Services
Agreement governing amendments thereto.

               SECTION 13. Assignment. Neither this Agreement nor the Launch
Services Agreement may be assigned by any party hereto or thereto without the
prior written consent of the other parties hereto or party thereto, as the case
may be.

               SECTION 14.  Launch Services Agreement.  The LSA Party and the
Customer (if not the LSA Party) hereby consent to the disclosure by AE of the
Launch Services



                                      -6-
<PAGE>   7




Agreement in connection with the financing provided pursuant to the Customer
Loan Agreement.

               SECTION 15.  GOVERNING LAW.  THE RIGHTS AND DUTIES OF THE
PARTIES HERETO UNDER THIS AGREEMENT SHALL BE GOVERNED BY THE
LAW OF FRANCE.

               Each of the parties to this Agreement hereby irrevocably waives
any right to have any dispute arising out of or in connection with this
Agreement be brought in French courts and expressly waives any right to the
immunity of jurisdiction provided in article 15 of the French civil code.



                                      -7-
<PAGE>   8


               IN WITNESS WHEREOF, the parties hereto have caused this
Multiparty Agreement to be duly executed, which execution may be in separate
counterparts and taken together an original, and delivered by their proper and
duly authorized Responsible Officers as of the day and year first above written.


                                ARIANESPACE S.A.


                                By:
                                    ---------------------------------
                                    Name:
                                    Title:
                                    Address:   Boulevard De l'Europe
                                               B.P. 177
                                               91006 Evry Cedex-France
                                    Telecopier: 33(0) 1 6087 6488



                                ARIANESPACE FINANCE S.A.


                                 By: /s/ B. Vienne
                                    ---------------------------------
                                    Name:   Brigitte Vienne
                                    Title:  Le Directeur-General
                                    Address:  18, rue Dicks
                                              L-1016 Luxembourg
                                    Telecopier: 33(0) 1 6087 6488


                                CD RADIO INC.


                                By:      /s/ David Margolese
                                    ---------------------------------
                                    Name:  David Margolese
                                    Title: Chairman and CEO
                                    Address:  1002 22nd Street, N.W.
                                              Washington, DC 10037
                                    Telecopier: (202) 296-6265







                                     
<PAGE>   9



                                                                       EXHIBIT A
                                                         TO MULTIPARTY AGREEMENT


                                  July 22, 1997




Arianespace Finance S.A.
18 rue Dicks
L-1016 Luxembourg

Attention: Director General


               Re:     Loan Proceeds Payment Instruction


Ladies and Gentlemen:

               Reference is hereby made to the Arianespace Customer Loan
Agreement, relating to Launch #1, dated as of July 22, 1997, between CD Radio
Inc. (the "Customer") and Arianespace Finance S.A. (the "Customer Loan
Agreement"). Capitalized terms used and not defined otherwise herein shall have
the meanings specified in the Customer Loan Agreement.

               You are hereby irrevocably instructed to deposit the proceeds of
all Loans to be disbursed to the Customer pursuant to the Customer Loan
Agreement into the following account:

                              Credit Lyonnais Luxembourg S.A.
                              Account Number: 036122-43

               The rights and obligations of the parties hereto shall be
governed by the law of the State of New York.

               No amendment, waiver, revocation or termination of this payment
instruction letter or any term hereof shall be effective unless consented to in
writing by all parties hereto.




<PAGE>   10



               Please acknowledge receipt of this payment instruction letter by
executing a copy of this letter in the space provided and returning it to the
Customer at the address for notices in the Customer Loan Agreement, with a copy
to Mr. Gantois and Mr. de Toldi at Credit Lyonnais IFAP TEIC, 1 rue des
Italiens, 75009 Paris, France, telecopier number 33(0) 1 4295 0382.

                                Very truly yours,

                                CD RADIO INC.


                                By: /s David Margolese
                                    ---------------------------------
                                    Name:  David Margolese
                                    Title: Chairman & CEO


Receipt acknowledged:

ARIANESPACE FINANCE S.A.


By:   /s/ B. Vienne
   ------------------------------
   Name:  Brigitte Vienne
   Title: Le Directeur-General


Acknowledged and agreed to:

CREDIT LYONNAIS


By:
   -------------
   Name:
   Title:




                                       -2-

<PAGE>   11



                                                                      EXHIBIT B
                                                        TO MULTIPARTY AGREEMENT


                                  July 22, 1997




Arianespace S.A.
Boulevard de l'Europe
B.P. 177
91006 Evry Cedex
France

Attention: Director General


               Re:     Launch Services Agreement Payment Instruction


Ladies and Gentlemen:

               Reference is hereby made to the Launch Services Agreement dated
as of July 22, 1997, between CD Radio Inc. (the "LSA Party") and Arianespace
S.A., as amended by the Multiparty Agreement relating to Launch #1 dated as of
July 22, 1997, among Arianespace S.A., Arianespace Finance S.A. and CD Radio
Inc. (the "Multiparty Agreement") (as so amended, the "Launch Services
Agreement"). Capitalized terms used and not defined otherwise herein shall have
the meanings specified in the Multiparty Agreement.

               You are hereby irrevocably instructed to deposit any funds
payable to the LSA Party pursuant to the terms of the Launch Services Agreement
with respect to the Launch into the following account:

                              Credit Lyonnais New York
                              Account Number: 0-100-682-000-100
                              CLA Reference:      IFAP/TEIC/AEF/036123-44

               The rights and obligations of the parties hereto shall be
governed by the law of the State of New York.

               No amendment, waiver, revocation or termination of this payment
instruction letter or any term hereof shall be effective unless consented to in
writing by all parties hereto. This payment instruction letter shall not in any
way affect the terms or the validity of the delegation set forth in Section 8 of
the Multiparty Agreement.



<PAGE>   12


               Please acknowledge receipt of this payment instruction letter by
executing a copy of this letter in the space provided and returning it to the
LSA Party at the address for notices in the Multiparty Agreement, with a copy to
Mr. Gantois and Mr. de Toldi at Credit Lyonnais IFAP TEIC, 1 rue des Italiens,
75009 Paris, France, telecopier number 33(0) 1 4295 0382.

                                Very truly yours,

                                CD RADIO INC.


                                By:    /s/ David Margolese
                                   ----------------------------------
                                   Name:  David Margolese
                                   Title: Chairman & CEO

Receipt acknowledged:

ARIANESPACE S.A.


By:
   -------------------
   Name:
   Title:


Acknowledged and agreed to:

CREDIT LYONNAIS


By:
   -------------------
   Name:
   Title:


                                       -2-

Source: OneCLE Business Contracts.