Document:

EXHIBIT 10.42
--------------------------------------------------------------------------------

                              ASSET SALE AGREEMENT

                                     BETWEEN

                         MOTIENT SATELLITE VENTURES LLC

                                       AND

                              MOTIENT SERVICES INC.

                                   DATED AS OF

                                 June 29, 2000

--------------------------------------------------------------------------------
<PAGE>

                                TABLE OF CONTENTS

                                                                            Page

1.    DEFINITIONS..............................................................1
2.    CLOSING OF ASSET SALE....................................................1
      2.1.     Sale of Assets..................................................1
      2.2.     Purchase Price; Deposit.........................................1
      2.3.     Description of Subject Assets...................................2
      2.4.     Excluded Assets.................................................4
      2.5.     Assumption of Specified Liabilities.............................5
      2.6.     Closing; Closing Date...........................................6
      2.7.     Agreement on Disposition of Purchase Price......................6
3.    ADDITIONAL UNDERTAKINGS AND COVENANTS....................................6
      3.1.     Consents and Approvals..........................................6
      3.2.     Operation of Business of Motient Services.......................7
      3.3.     Disclosure......................................................8
      3.4.     News Releases...................................................9
      3.5.     General.........................................................9
      3.6.     Bulk Sales Laws.................................................9
      3.7.     Access to Motient Services Information; Business Review Period..9
               3.7.1.  Business Review.........................................9
               3.7.2.  Confidentiality........................................10
               3.7.3.  Basic Financial Information............................10
               3.7.4.  Newco Information Rights; Confidentiality..............11
      3.8.     Revision of Disclosure Schedules...............................11
4.    REPRESENTATIONS AND WARRANTIES OF MOTIENT SERVICES......................12
      4.1.     Organization and Standing......................................12
      4.2.     Subsidiaries...................................................12
      4.3.     Noncontravention...............................................12
      4.4.     Real Property..................................................13
      4.5.     Assets.........................................................13
      4.6.     Insurance......................................................13
      4.7.     Intellectual Property..........................................13
      4.8.     Debt Instruments...............................................14
      4.9.     Leases.........................................................14
      4.10.    Other Agreements...............................................14
      4.11.    Litigation; Disputes...........................................15
      4.12.    Labor Relations; Employees.....................................15
      4.13.    Taxes..........................................................16
      4.14.    Restrictions and Consents......................................16
      4.15.    Authorization..................................................17
      4.16.    Absence of Violation...........................................17
      4.17.    Binding Obligation.............................................17
      4.18.    Financial Statement............................................17
      4.19.    Absence of Undisclosed Liabilities.............................18
      4.20.    Material Adverse Change........................................18
      4.21.    Assets Used in Satellite Communications Business...............18
      4.22.    Licenses.......................................................18
      4.23.    Transactions with Affiliates...................................18
      4.24.    Employee Benefit Plans.........................................18
      4.25.    Environmental Matters..........................................19

                                      -i-

<PAGE>

5.    REPRESENTATIONS AND WARRANTIES OF NEWCO.................................19
      5.1.     Organization and Standing......................................19
      5.2.     Authorization..................................................20
      5.3.     Binding Obligation.............................................20
6.    CONDITIONS PRECEDENT TO OBLIGATIONS OF MOTIENT SERVICES.................20
      6.1.     Representations and Warranties.................................20
      6.2.     Performance....................................................20
      6.3.     Legal Proceedings..............................................21
      6.4.     Hart-Scott-Rodino..............................................21
      6.5.     Newco's Certificate............................................21
      6.6.     Federal Communications Commission Consent......................21
7.    CONDITIONS PRECEDENT TO OBLIGATIONS OF NEWCO............................21
      7.1.     Representations and Warranties.................................21
      7.2.     Performance....................................................22
      7.3.     Legal Proceedings..............................................22
      7.4.     Hart-Scott-Rodino..............................................22
      7.5.     Officer's Certificate..........................................22
      7.6.     Federal Communications Commission Consent......................22
      7.7.     Financing......................................................22
      7.8.     No Material Adverse Effect.....................................23
8.    Closing.................................................................23
      8.1.     Deliveries by Motient Services.................................23
      8.2.     Deliveries by Newco............................................23
      8.3.     Transferred Employees..........................................24
      8.4.     Transitional Matters...........................................25
      8.5.     Shared Assets; Parent Guaranties...............................26
      8.6.     Motient Resale Of Newco Products And Services..................27
      8.7.     Use of Proceeds................................................27
      8.8.     Insurance Proceeds from Satellite Failure......................27
      8.9.     Sale of Motient Services or the Satellite
               Communications Business........................................28

                                      -ii-

<PAGE>

9.    SURVIVAL OF REPRESENTATIONS; INDEMNIFICATION; REMEDIES..................30
      9.1.     Survival of Representations....................................30
      9.2.     Agreement of Motient Services to Indemnify.....................30
      9.3.     No Duplication of Remedies.....................................31
      9.4.     Agreement of Newco to Indemnify................................31
      9.5.     Notice of Claims...............................................31
      9.6.     Limitations on Amounts.........................................32
      9.7.     Force Majeure..................................................33
      9.8.     Subrogation....................................................33
10.   TERMINATION.............................................................33
      10.1.    Termination....................................................33
      10.2.    Effect of Termination..........................................34
11.   MISCELLANEOUS...........................................................34
      11.1.    Additional Actions and Documents...............................34
      11.2.    No Brokers.....................................................34
      11.3.    Expenses.......................................................34
      11.4.    Assignment.....................................................35
      11.5.    Entire Agreement; Amendment....................................35
      11.6.    Waiver.........................................................35
      11.7.    Severability...................................................35
      11.8.    Governing Law..................................................36
      11.9.    Notices........................................................36
      11.10.   Headings.......................................................37
      11.11.   Interpretation; Absence of Presumption.........................37
      11.12.   Execution in Counterparts......................................38
      11.13.   Limitation on Benefits.........................................38
      11.14.   Binding Effect.................................................38

                                     -iii-

<PAGE>

                              ASSET SALE AGREEMENT

     ASSET SALE AGREEMENT (this "Sale Agreement") is entered into as of June 29,
2000 by and between Motient Satellite Ventures LLC, a Delaware limited liability
company ("Newco"),  and Motient Services Inc., a Delaware corporation  ("Motient
Services").

     WHEREAS, Motient Services is engaged in the business of providing satellite
communications  services  (including though a dual-mode  communications  product
offering)  in the United  States and  surrounding  waters  and  airspace  in the
1530-1559  Mhz  and  1631.5-1660.5  Mhz  band  (the  "Satellite   Communications
Business");

     WHEREAS,  Motient  Services  desires to sell and Newco  desires to purchase
certain of the assets and assume  certain of the  liabilities  of the  Satellite
Communications Business, as more fully described herein.

     NOW,  THEREFORE,  in  consideration  of the  foregoing  and  of the  mutual
covenants and agreements set forth herein, the parties,  intending to be legally
bound, hereby agree as follows:

1.       DEFINITIONS

     For all  purposes of this Sale  Agreement,  certain  capitalized  terms not
otherwise defined herein shall have the meanings set forth on Exhibit A.

2.       CLOSING OF ASSET SALE

2.1.     Sale of Assets.

     On the basis of the  representations,  warranties and agreements  contained
herein, and subject to the terms and conditions hereof,  Motient Services agrees
to sell,  assign,  transfer,  convey and deliver to Newco,  and Newco  agrees to
purchase from Motient Services, the Subject Assets at the Closing free and clear
of all Claims or Encumbrances other than the Assumed Liabilities.

2.2.     Purchase Price; Deposit.

     (a) For and in consideration  of the conveyances and assignments  described
herein and in addition to the  assumption of liabilities as set forth in Section
2.5, Newco agrees to pay to Motient  Services,  and Motient  Services  agrees to
accept from Newco, the Purchase Price which shall be payable as follows:

          (i) For and in  consideration  of the  execution  and delivery of this
Agreement,  simultaneously  with the execution  and delivery of this  Agreement,
Newco is delivering the amount of Twenty Four Million Dollars  ($24,000,000)  in
cash to Motient  Services as an earnest money deposit (the  "Deposit")  which is
non-refundable  except  in  connection  with  (and  to the  extent  of)  Motient
Services'  obligation to indemnify  hereunder and except as otherwise  expressly
set forth in this Sale Agreement; and

<PAGE>

          (ii) At the Closing,  Newco shall  deliver the balance of the Purchase
Price to Motient  Services by wire transfer of  immediately  available  funds in
accordance with Motient Services' wiring instructions.

     (b) Motient  Services shall have no obligation to hold or otherwise  retain
the Deposit in escrow and Motient Services shall have the right to use and apply
the Deposit in its sole  discretion,  subject to the  restrictions  set forth in
Section 8.8 hereof.

2.3.     Description of Subject Assets

     All of the assets  that  relate to the  Satellite  Communications  Business
shall be the "Subject Assets",  excluding in all events, the Excluded Assets (as
hereinafter defined). The Subject Assets include, but are not limited to:

     (a) the satellite  described on Schedule 2.2(a) and any replacement thereof
(the "Satellite");

     (b) subject to regulatory approval,  all of Motient Services' rights in any
licenses  issued  by  the  Federal  Communications  Commission,  and  all  other
licenses,  permits,  franchises  and  similar  authorizations  held  by  Motient
Services,  in  connection  with  the  Satellite   Communications  Business  (the
"Licenses");

     (c) all of Motient Services' rights in customer  contracts  relating to (i)
voice  services,  including but not limited to nationwide  dispatch  service and
satellite telephone service,  (ii) data services,  including  satellite-only and
multi-mode  messaging  services and (iii) private network  customers  purchasing
bulk satellite capacity (the "Customer Contracts");

     (d) all of Motient Services' rights in the dealer contracts relating to the
Satellite Communications Business (the "Dealer Contracts");

     (e) all of Motient  Services'  rights in the  distributor,  sale, agent and
reseller  contracts  with  Stratos  relating  to  the  Satellite  Communications
Business (the "Stratos Contracts");

     (f) all of Motient  Services' rights and obligations under (i) the contract
to purchase a certain number of MobileMAX2  units, and (ii) all other agreements
related thereto (the "MobileMAX2 Agreements");

     (g)  subject to  Section  8.4 hereof  and the  Landlord's  consent,  all of
Motient  Services' rights and obligations under the Deed of Lease (the "Lease"),
dated February 4, 1993, as amended,  between Motient  Services and Trust Company
of the West  (the  "Landlord")  for the  premises  located  at  10802  Parkridge
Boulevard, Reston, Virginia (the "Reston Facility");

                                      -2-

<PAGE>
     (h)  all  of  Motient  Services'  rights  in  the  other  leases,   license
agreements,  contracts, agreements, sales orders, purchase orders, open bids and
other commitments primarily relating to the Satellite  Communications  Business,
including but not limited to (i) agreements relating to telemetry,  tracking and
control  services,  (ii) agreements  relating to back-up antenna support,  (iii)
supply,  distribution and software maintenance  agreements,  (iv) administrative
services   agreements,    (v)   cross-licensing    agreements   (including   the
Cross-Licensing  Agreement),  (vi) reciprocal business  arrangements,  and (vii)
leases  relating to real property (the "Other  Contracts"  and together with the
Customer Contracts,  the Dealer Contracts, the Stratos Contracts, the MobileMAX2
Agreements and the Lease, the "Contracts");

     (i) all  machinery,  fixtures,  equipment,  supplies,  computers,  computer
systems  and  computer  support  equipment,  and  all  other  tangible  personal
property,  relating to the Satellite  Communications Business including, but not
limited  to, all of the  equipment  and  personal  property  comprising  Motient
Services' land earth stations;

     (j) all of Motient  Services'  rights under the  contracts,  agreements and
arrangements   with   employees  of  Motient   Services   whose   employment  is
substantially related to the Satellite Communications Business;

     (k) all of the  machinery,  equipment,  furniture,  furnishings  and  other
tangible personal property of Motient Services used primarily in connection with
the Satellite Communications Business (collectively, the "Personal Property");

     (l) all of Motient Services' rights in the patents, trademarks, copyrights,
licenses to use patents,  trademarks or copyrights of third  parties,  patent or
trademark or  copyright  applications  or  registrations,  trade names,  service
marks, applications,  logos, slogans, computer code and software, trade secrets,
know how, customer lists and proprietary  information  relating to the Satellite
Communications Business (the "Intellectual Property");

     (m) all stock and other  outstanding  equity  securities  owned by  Motient
Services;

     (n) all inventory,  work-in-progress,  raw materials,  parts, stores, spare
parts, repair parts, test units, samples,  components,  accessories and supplies
related to the Satellite Communications Business;

     (o) the prepaid  expenses,  deposits  and  retentions  of Motient  Services
related to the Satellite Communications Business;

     (p) all goodwill and going concern  value of the  Satellite  Communications
Business;

     (q) all rights or Claims of Motient  Services  arising out of the breach of
any  express  or implied  warranties  by third  parties of any of the  foregoing
assets or any component part thereof;

                                      -3-

<PAGE>

     (r) all  security  deposits  and  letters  of credit  provided  to  Motient
Services from certain customers of the Satellite Communications Business;

     (s)  all  rights  of  Motient  Services  as a  creditor  in the  bankruptcy
proceedings  listed in  Schedule  2.2(r) to the extent  such rights are still in
existence at the Closing;

     (t)  the  satellite  in-orbit  insurance  policy  and all  other  insurance
policies substantially related to the Satellite Communications Business;

     (u) all rights of Motient  Services  to any  Claims,  ongoing or  potential
against  any  third  parties   arising  out  of  or  related  to  the  Satellite
Communications Business;

     (v) except as provided in Section 2.4(v) below, all accounts  receivable of
the  Satellite  Communication  Business,  whether  such  rights  are  matured or
unmatured, fixed or contingent, as of the Closing Date;

     (w) the cash or cash  equivalents  held by or deposited  with any financial
institution in connection with the letters of credit issued on behalf of Motient
Services; and

     (x) all assets  reflected  on the  Financial  Statement,  other than assets
disposed of in compliance  with this Sale Agreement and the Shared Assets listed
on Schedule 2.3(x) of the Disclosure Schedule.

2.4.     Excluded Assets; Unassignable Contracts

     (a) "Excluded Assets" consist of (i) Motient Services'  corporate  charter,
qualifications to conduct business as a foreign  corporation,  arrangements with
registered  agents  relating  to  foreign  qualifications,  taxpayer  and  other
identification  numbers,  seals, minute books, stock transfer books, blank stock
certificates,   and  other  documents   relating  solely  to  the  organization,
maintenance  or existence  of Motient  Services as a  corporation,  (ii) Motient
Services'  rights with respect to Intercompany  Agreements (as defined  herein),
(iii)  except as  provided  in  Sections  2.3(v) and (w)  hereof,  cash and cash
equivalents  (including without limitation the Purchase Price),  (iv) the Shared
Assets,  (v) that portion of the accounts  receivable  of Motient  Services that
relate to state and local  excise,  sales and use taxes  required  to be paid by
Motient  Services  under  Section  2.5(z)  hereof and, (vi) the assets listed on
Schedule 2.4.

     (b)  Notwithstanding  anything else in this Sale Agreement to the contrary,
this Sale Agreement  shall not constitute an agreement to assign or transfer any
Subject  Asset or part thereof or any rights or benefit  arising  thereunder  or
resulting therefrom if an attempted assignment or transfer thereof,  without the
consent of a third party thereto,  would  constitute a breach  thereof,  or make
Newco, Motient Services or any of their respective Affiliates liable for damages
or other  penalties  thereunder  (although the  obligations of Motient  Services
thereunder  shall  remain  Assumed  Liabilities  for all  purposes  of this Sale
Agreement).  If such  consent is not  obtained,  or if an  attempted  assignment

                                      -4-

<PAGE>

thereof  would be  ineffective  or would  affect  the rights of Newco or Motient
Services  so that  Newco  would not in fact  receive  all such  rights,  Motient
Services (i) shall cooperate with Newco, at Newco's  request,  in endeavoring to
obtain  such  consent  and  (ii) if any  such  consent  is  unobtainable,  shall
cooperate with Newco in an arrangement  designed to provide to Newco, at Newco's
expense, the benefits and liabilities following Closing with respect to any such
Subject  Asset or part  thereof or any right or benefit  arising  thereunder  or
resulting therefrom,  including  enforcement for the benefit of Newco of any and
all rights of Motient  Services  against a third party arising out of the breach
or cancellation by such third party or otherwise;  provided,  however, that such
arrangement  shall  provide for  indemnification  by Newco of Motient  Services,
reasonably acceptable to Motient Services,  against any liability arising out of
such arrangement.

2.5.     Assumption of Specified Liabilities

     At the  Closing,  Newco shall  assume only the  following  liabilities  and
obligations   of   the   Satellite   Communications   Business   (the   "Assumed
Liabilities"):  all liabilities and indebtedness  relating to the Subject Assets
(other  than  those  incurred  in  violation  of this Sale  Agreement  and those
excluded by the second paragraph of this Section 2.5), including but not limited
to (i) equipment and insurance  financing,  (ii) performance  payments to Hughes
relating to satellite manufacture,  (iii) the SPAR litigation,  (iv) obligations
under the Asset Sale  Agreement,  dated as of November  22,  1996 with  Rockwell
Collins,  (v) warranty obligations to customers under customer service contracts
assumed  by  Newco,  (vi)  accounts  payable  of  the  Satellite  Communications
Business,   whether  such  obligations  are  matured  or  unmatured,   fixed  or
contingent,  as of the Closing  Date,  (vii) all Claims by  customers,  vendors,
suppliers,  Transferred  Employees  and similar  Claims,  relating to any of the
Subject Assets or the Satellite  Communications Business, and (viii) any and all
termination  penalties under any contracts  assigned to Newco that Newco chooses
to terminate.

     The Assumed Liabilities shall not include, and Newco shall not assume or be
deemed to assume, and Motient Services shall remain responsible for, any and all
debts, liabilities or obligations of Motient Services (or any officer, director,
employee or  shareholder of any of the  foregoing) of the following  types:  (p)
liabilities  that were required to be disclosed on the  Disclosure  Schedule (or
the updated  Disclosure  Schedule)  which were not so  disclosed,  (q) all taxes
Motient  Services is responsible for under the last sentence of Article V of the
R&D agreement,  (r) liabilities and obligations to Motient Corporation or any of
its direct or indirect  Subsidiaries  (except those obligations set forth in the
Cross-Licensing  Agreement),  (s)  indebtedness  incurred  under and  guaranties
related  to any  bank or  credit  facilities  of  Motient  Corporation,  Motient
Holdings Inc. or any other entity other than Motient  Services,  (t) liabilities
and  obligations  arising  out  of or  relating  to  (including  guaranties  of)
indebtedness  for borrowed  money (except for  indebtedness  for borrowed  money
permitted to be incurred  under Section  3.2(c)(ii)  hereof),  (u) any liability
arising  out of a  breach  of this  Sale  Agreement,  the R&D  Agreement  or any
Agreement or document  delivered in connection  herewith or  therewith,  (v) any
costs directly  associated with the Closing,  including but not limited to legal
and  accounting  fees,  (w) any  liability  to  those  former  employees  of the
Satellite  Communication  Business whose  employment was terminated prior to the

                                      -5-

<PAGE>

Closing Date and who are eligible to receive COBRA  benefits under Section 4980B
of the Code,  (x) any  liabilities  under any  contract of Motient  Services not
included  in the Subject  Assets or any  termination  payments or other  damages
payable with respect to an unassigned  contract not disclosed to Newco,  (y) any
Liability of Motient  Services  for the unpaid  Taxes of any Person  (other than
Motient  Services) under Treas.  Reg. Section 1.1502-6 (or any similar provision
of state,  local or foreign law),  as a transferee or successor by contract,  or
otherwise,  and (z) any  Liability  of Motient  Services  for unpaid  Taxes with
respect to any Tax year or portion thereof ending on or before the Closing Date;
including  for  state and local  excise,  sales and use taxes  paid on a monthly
basis,  with respect to which  Motient  Services  shall be liable for such Taxes
with respect to sales made prior to the Closing Date.

2.6.     Closing; Closing Date.

     The closing of the sale of the Subject  Assets to Newco and the  assumption
of the Assumed  Liabilities  by Newco (the  "Closing" and the date thereof being
sometimes  hereinafter  referred to as the  "Closing  Date") shall be as soon as
reasonably  practicable  after the satisfaction of the conditions  precedent set
forth in Sections 6 and 7. The  Closing  shall be held at the offices of Hogan &
Hartson L.L.P., 8300 Greensboro Drive, Suite 1200, McLean, Virginia 22102, or at
such other location as the parties may mutually agree upon.

2.7.     Agreement on Disposition of Purchase Price

     Motient  Services  hereby  agrees  that the amount of the  Purchase  Price,
together with the assumption of the Assumed  Liabilities,  constitutes  adequate
and sufficient  consideration for the transfer to Newco of all interests held by
Motient Services in and to the Subject Assets and for the performance by Motient
Services of all of its covenants and  agreements  hereunder.  Within ninety (90)
days after the Closing  Date,  the parties will come to a  mutually-agreed  upon
allocation of the consideration for tax and accounting purposes.

3.       ADDITIONAL UNDERTAKINGS AND COVENANTS

     Newco,  on the one hand, and Motient  Services,  on the other hand,  hereby
covenant and agree with each other as follows:

3.1.     Consents and Approvals

     (a) Upon  written  notice from Newco (the  "Notice")  delivered  to Motient
Services  on or prior to the  Outside  Date  (the  date of  receipt  of which is
referred  to  herein  as the  "Notice  Date")  stating  that  Newco  desires  to
consummate the purchase of the Subject Assets,  Newco and Motient Services shall
use all commercially reasonable efforts to secure such consents,  authorizations
and approvals of governmental and  supragovernmental  authorities  including but
not limited to the Federal Communications  Commission and of private individuals
or  entities  with  respect  to  the  transactions  contemplated  by  this  Sale
Agreement,  and to the  performance  of all other  obligations  of such  parties
hereunder,  as may be required by any  applicable  statute or  regulation of the
United States or any country, state or other jurisdiction or by any Agreement of

                                   -6-

<PAGE>

any kind  whatsoever  to which Newco or Motient  Services is a party or by which
Newco or Motient Services is bound.  Subject to Section 3.1(c), each party shall
be responsible  for any expenses  incurred  relating to obtaining such consents,
authorizations  and approvals for which such party bears the  responsibility  of
obtaining.

     (b) After the Notice Date,  Newco and Motient  Services shall (i) cooperate
in the filing of all forms,  notifications,  reports  and  information,  if any,
required or reasonably deemed advisable pursuant to applicable statutes,  rules,
regulations  or orders of any  governmental  or  supragovernmental  authority in
connection  with the  transactions  contemplated by this Sale Agreement and (ii)
use all commercially  reasonable efforts to cause any applicable waiting periods
thereunder to expire and any objections to the transactions  contemplated hereby
to be withdrawn before the Closing.

     (c) In addition to the obligations set forth in Section 3.1(b), as promptly
as practicable,  and in any event no later than ten (10) business days after the
Notice Date,  Motient  Services and Newco shall  complete any filing that may be
required  pursuant to  Hart-Scott-Rodino,  or shall  mutually agree that no such
filing is required.  Motient  Services and Newco shall diligently take (or fully
cooperate in the taking of) all actions, and provide any additional information,
required or  reasonably  requested in order to comply with the  requirements  of
Hart-Scott-Rodino.  Each  party  shall  pay any  Hart-Scott-Rodino  filing  fees
payable in connection with any  Hart-Scott-Rodino  filing required to be made by
such party.

3.2.     Operation of Business of Motient Services

     (a) Motient  Services  shall,  through the Closing Date, (i)  substantially
preserve its business organization,  including, without limitation all licenses,
permits or other  governmental  authorizations  to conduct  its  business,  (ii)
operate the Satellite Communications Business in the ordinary course of business
consistent  with  past  practice,   (iii)  substantially  maintain  its  present
relationships with customers,  suppliers,  consultants,  employees and any other
persons having business  relations with it (subject to Motient Services' ability
to  terminate  arrangements  that  are  detrimental  to  the  well-being  of the
Satellite  Communications  Business),  (iv) collect accounts  receivable and pay
expenses and accounts payable in the ordinary course of business consistent with
past  practice,  and (v)  maintain the Subject  Assets in  customary  repair and
condition, provided, that a non-ordinary course change in the business condition
occurs beyond the control of Motient Services (excluding,  however, such changes
which any company  controlling  Motient  Services  causes or  instructs  Motient
Services to make) shall not be deemed in breach of this Section 3.2.

     (b) Prior to the Closing Date,  Motient  Services will maintain the Subject
Assets in accordance with Section 4.5.

     (c) Prior to the Closing Date,  Motient  Services shall not take any of the
following  actions  without the  consent of Newco,  which  consent  shall not be
unreasonably withheld:

                                      -7-

<PAGE>

          (i) enter into or amend any  employment  agreements  or  arrangements,
except in the ordinary course of business;

          (ii) incur any  indebtedness  for borrowed money, or guaranty any such
indebtedness  of another person,  in excess of $2,000,000,  except in connection
with  (1)  financing  up to  $6,000,000  in the  aggregate  in  connection  with
satellite  insurance   policies,   (2)  equipment  or  vendor  financing  up  to
$15,000,000  in the  aggregate  related  to the  MobileMAX2  Agreements  (or any
extensions or renewals thereof),  and (3) other equipment or vendor financing up
to $5,000,000 in the aggregate.

          (iii)  enter  into  any  transactions  with an  Affiliate  of  Motient
Services,  unless  such  transaction  is either  (i) in the  ordinary  course of
business  consistent  with  Motient  Services'  past  practice  in dealing  with
Affiliates,  or (ii) negotiated at arms length between the parties,  on terms at
least as  favorable  as those that could be  obtained  by an  independent  third
party,  and is  determined  to be fair by the  board  of  directors  of  Motient
Services;

          (iv) acquire or agree to acquire, by merging or consolidating with, by
purchasing an equity  interest in or a portion of the assets of, or by any other
manner, any business or corporation,  partnership, association or other business
organization or division thereof;

          (v) fail to maintain  satellite and ground station insurance  coverage
(to the  extent  available  on  commercially  reasonable  terms),  on its own or
through Motient  Corporation's  policies,  that is consistent with past practice
and  reasonably  consistent  with the  coverage of Motient  Corporation's  other
subsidiaries;

          (vi)  enter into any  Agreements  that  require  Motient  Services  to
repurchase  products  upon a  transfer  of such  Agreement  or upon a change  in
control of the Satellite Communication Business;

          (vii) hypothecate, mortgage, pledge, charge or encumber, or permit any
mortgage,  pledge or  encumbrance  to exist  on,  any of its  Assets,  except in
connection with indebtedness  permitted to be incurred under Section  3.2(c)(ii)
above; or

          (viii) sell,  lease,  transfer or  otherwise  dispose of, or purchase,
lease or  otherwise  acquire,  any  Assets,  except  in the  ordinary  course of
business.

3.3.     Disclosure

     If, at any time prior to Closing,  Motient  Services  becomes  aware of any
information which would cause any condition set forth in Sections 7.1 or 7.2 not
to be satisfied,  Motient Services  covenants that it will promptly inform Newco
thereof.

                                      -8-

<PAGE>

3.4.     News Releases

     Neither  party  shall  issue or approve  any news  release or other  public
announcement (including,  but not limited to, any public announcement to clients
and/or vendors) concerning the transactions  contemplated by this Sale Agreement
without  the prior  approval  of the other party  (which  approval  shall not be
unreasonably withheld),  except as may be otherwise necessary or appropriate for
compliance with federal or state  securities laws or applicable  requirements of
any securities exchange,  automated quotation system or over-the-counter  market
as long as such disclosing  party uses  reasonable  efforts to consult the other
prior to such disclosure or filing.

3.5.     General

     Each of the parties hereto will use all commercially  reasonable efforts to
take all action and to do all things necessary, proper, or advisable in order to
consummate  and  make  effective  the  transactions  contemplated  by this  Sale
Agreement (including  satisfaction,  but not waiver, of the conditions set forth
in Sections 6 and 7).  Notwithstanding  the foregoing,  nothing contained herein
shall  require  Motient  Corporation,  Motient  Holdings  Inc.  or any of  their
respective  Affiliates  to (i) enter into new  guaranties or incur new secondary
liabilities   of  any  kind  to  any  customers  or  vendors  of  the  Satellite
Communications  Business, or (ii) except as expressly set forth herein, make any
payments  or incur any  liability  to any  third  party in  connection  with the
assignment and transfer of the Contracts or any other  Agreement that is part of
the Subject Assets to Newco.

3.6.     Bulk Sales Laws.

     Newco hereby waives compliance by Motient Services,  in connection with the
transactions  contemplated  hereby,  with the provisions of any applicable  bulk
transfer laws; provided, however, that Motient Services shall indemnify and hold
harmless  Newco from and against any losses  attributable  to Motient  Services'
non-compliance  with any applicable  bulk transfer  laws,  without regard to the
provisions of Article 9.

3.7.     Access to Motient Services Information; Business Review Period

3.7.1.   Business Review.

     After the Notice Date,  Motient Services shall,  upon the request of Newco,
provide  to  Newco  and  its  representatives   full  access  to  all  premises,
properties,  officers,  directors,  consultants,   contractors,  books,  records
(including, without limitation, tax returns, tax records and correspondence with
accountants), contracts and documents pertaining to the Satellite Communications
Business as Newco deems  necessary  (the "Business  Review"),  and Newco and its
representatives shall have the right to copy such books, records,  contracts and
documents at Newco's expense.  Motient Services shall cooperate fully with Newco
and  its  representatives  in  permitting  reasonable  access  to the  Satellite
Communications  Business  to conduct  the  Business  Review.  Such access may be
either during normal  business  hours or after normal  business  hours after the

                                      -9-

<PAGE>

giving of reasonably advance notice to Motient Services.  Newco shall reasonably
restore any  property of Motient  Services  damaged as a result of the  Business
Review to its condition  prior to any such Business  Review and shall  indemnify
and defend  Motient  Services  from any and all  liability  which may arise as a
result of the  performance of Business  Review by Newco.  Motient  Services will
furnish to Newco and its  representatives  such financial and operating data and
other information with respect to the Satellite Communications Business as Newco
may reasonably request,  including,  without limitation,  financial  statements,
books and records and  Agreements  with clients,  customers,  vendors,  lessors,
licensors and suppliers of the Satellite Communications Business.

3.7.2.   Confidentiality.

     Prior to commencing the Business Review, each of Newco and Motient Services
shall enter into a  confidentiality  agreement  with respect to all  information
provided  to it  pursuant  to this Sale  Agreement  (or in  connection  with the
transactions contemplated hereby).

3.7.3.   Basic Financial Information.

     Until the Closing Date,  Motient  Services  hereby  covenants and agrees to
furnish the following reports to Newco:

     (a) Within 105 days after the end of each fiscal year of Motient  Services,
a consolidated  balance sheet of Motient Services and its subsidiaries,  if any,
as of the end of such  fiscal  year,  which  balance  sheet  shall  be  prepared
consistently with the Financial Statement (unless otherwise indicated therein).

     (b) Within 75 days  after the end of each  quarterly  accounting  period in
each  fiscal  year of Motient  Services,  (i) a  consolidated  balance  sheet of
Motient  Services  and  its  subsidiaries,  if any,  as of the end of each  such
quarterly  period,  which balance sheet shall be prepared  consistently with the
Financial Statement (unless otherwise  indicated therein),  and (ii) a pro forma
presentation  of the operating  results of Motient  Services for such  quarterly
period based upon reasonable  assumptions to be agreed upon by Motient  Services
and Newco.

     (c) Within 45 days after the end of each month, such monthly operating data
and other  financial  information  in form and substance as the parties agree is
reasonable;  provided that no such information  shall be required to be prepared
in accordance with generally accepted accounting principles.

     (d)  Along  with  the  statements  required  to be  delivered  to  Newco in
connection  with  Sections  3.7.3(a)  and (b),  management's  discussion  of any
material  changes in any such  statement  compared to the  previously  delivered
statement.

     (e) As soon as practicable following their release,  copies of all material
press  releases  issued by Motient  Services  or its  Affiliates  related to the
Satellite  Communications  Business or other material reports or  communications
delivered by Motient Services or its Affiliates to the financial  community with
respect to the Satellite Communications Business.

                                      -10-

<PAGE>

     Any  balance  sheet,  report  or other  information  delivered  by  Motient
Services to Newco  pursuant to this Section 3.7.3 shall be deemed to satisfy the
obligations  of Motient  Services  under the this Section  3.7.3 so long as such
balance sheet, report or other information was prepared in good faith.

3.7.4.   Newco Information Rights; Confidentiality.

     At  the  request  of  Newco,  Motient  Services  will  provide  Newco  with
reasonable  access during its normal business hours to (i) any of the properties
of Motient  Services,  including  its books of account and other records (and to
make  copies  thereof  and take  extracts  therefrom),  (ii)  Motient  Services'
officers and independent public accountants to discuss its affairs, finances and
accounts; provided that such access shall be conducted in a manner that does not
unreasonably  interfere  with the business or  operations  of Motient  Services.
Newco  hereby  agrees to hold in  confidence  and trust and not to  disclose  or
misuse any  confidential  information  provided to it  pursuant to this  Section
3.7.4 and to instruct any parties to whom it may transmit  such  information  as
provided  below  of the  confidential  nature  of  such  information;  provided,
however,  that the  foregoing  shall not  prohibit  Newco from  disclosing  such
information  (i) to its  board of  directors,  investment  advisers,  attorneys,
accountants,  consultants  and other  professionals  to the extent  necessary to
obtain their  services in  connection  with the possible  exercise of its rights
under this Sale Agreement, (ii) to Newco's stockholders and Affiliates, or (iii)
as required by applicable law or regulation,  regulatory  body,  stock exchange,
court or  administrative  order, or any listing  agreement  concerning  Newco or
Motient Services. 3.8. Revision of Disclosure Schedules

     Within ten (10) business days following the Notice Date,  Motient  Services
shall provide to Newco an update of the Financial Statement as of the end of the
most  recently  completed  month (or, in the event that fewer than  fifteen (15)
days have elapsed since the end of the most recently  completed fiscal month, as
of the end of the  month  immediately  preceding  the  most  recently  completed
month),  and shall provide to Newco a certificate of a senior executive  officer
of  Motient  Services,   making  on  behalf  of  Motient  Services  the  various
representations   and   warranties  set  forth  in  Article  4  and  such  other
representations  and  warranties as Newco may  reasonably  request  (except that
Motient   Services   shall  not  be  required   to  make  any  such   additional
representations  and  warranties  as to any  matters  as to which the  pertinent
information  is not  reasonably  available  to  it),  together  with  disclosure
schedules  updating  the  information  in  the  Disclosure  Schedules  delivered
herewith  and  taking  any  necessary  exceptions  to  the  representations  and
warranties not being made as of the date hereof, all as of the date delivered to
Newco (the "Update  Date").  As to  representations  and warranties  made on the
Update Date which are parallel to  representations  and  warranties  made on the
date hereof  pursuant to Section 4, the  Disclosure  Schedules  delivered on the
Update Date shall be updates of the  Disclosure  Schedules  delivered  herewith,
adding  relevant  information as to any pertinent  developments or changes since
the date hereof. As to other  representations  and warranties made on the Update
Date, the  Disclosure  Schedules  shall be prepared by Motient  Services in good
faith to reflect as fairly as possible the nature and scope of  exceptions  that
the parties hereto have agreed upon in connection with the Disclosure  Schedules
delivered herewith.

                                      -11-

<PAGE>

4.       REPRESENTATIONS AND WARRANTIES OF MOTIENT SERVICES

     Except as set forth in the Disclosure  Schedule,  Motient  Services  hereby
represents and warrants to Newco as follows:

4.1.     Organization and Standing

     Motient Services is a corporation  duly organized,  validly existing and in
good  standing  under  the laws of the State of  Delaware,  and has the full and
unrestricted corporate power and authority to own, operate and lease its Assets,
to carry on its  business as  currently  conducted,  to execute and deliver this
Sale Agreement and to carry out the transactions  contemplated  hereby.  Motient
Services is qualified to transact  business as a foreign  corporation in, and is
in good standing under the laws of, the jurisdictions  listed on Schedule 4.1 to
the Disclosure Schedule.

4.2.     Subsidiaries

     Motient  Services has no  subsidiaries  and no equity  investment  or other
interest  in  any  corporation,   association,  partnership,  limited  liability
company,  joint venture or other entity,  except as set forth on Schedule 4.2 to
the Disclosure  Schedule.  Motient Services has made no advances or loans to any
corporation,  association, partnership, limited liability company, joint venture
or other  entity  or  individual,  except as set  forth on  Schedule  4.2 to the
Disclosure  Schedule.  Motient  Services  Inc.  of  Virginia  is a  wholly-owned
subsidiary of Motient Services with no assets,  liabilities or commitments other
than as described on Schedule 4.2 of the Disclosure Schedule

4.3.     Noncontravention

     Except as disclosed on Schedule 4.3 to the Disclosure Schedule, neither the
execution and the delivery of this Sale Agreement,  nor the  consummation of the
transactions  contemplated hereby, will, (A) violate any constitution,  statute,
regulation, rule, injunction,  judgment, order, decree, ruling, charge, or other
restriction of any government,  governmental  agency,  or court to which Motient
Services  is subject  which  could  reasonably  be  expected  to have a Material
Adverse  Effect or, (B)  conflict  with,  result in a breach  of,  constitute  a
default  (or an event  which,  with  notice  or lapse  of time,  or both,  would
constitute a default) under,  result in the acceleration of, create in any party
the right to accelerate,  terminate,  modify,  or cancel,  or require any notice
under any agreement, contract, lease, license, instrument, note, bond, mortgage,
deed of trust,  or other  arrangement  existing to which  Motient  Services is a
party or by which  any of its  Assets  is  subject  which  would  reasonably  be
expected  to have a  Material  Adverse  Effect,  (c) result in the  creation  or
imposition  of any  Encumbrance  upon  any of the  Subject  Assets  which  could
reasonably be expected to have a Material Adverse Effect, or (d) violate Motient
Services' organizational documents.

                                      -12-

<PAGE>

4.4.     Real Property

     Motient Services does not own and has never owned any Real Property.

4.5.     Assets

     Motient Services has good, valid and marketable title to the Subject Assets
owned by it, free and clear of all  Encumbrances  (other than  Encumbrances  set
forth on Schedule 4.5) except where the failure to have such title or to be free
and  clear of such  Encumbrances  would not  reasonably  be  expected  to have a
Material Adverse Effect.

4.6.     Insurance

     Schedule 4.6 to the Disclosure Schedule lists all policies of title, asset,
fire, hazard, casualty,  liability,  life, worker's compensation and other forms
of  insurance of any kind owned or held by Motient  Services and such  insurance
coverage is reasonably  consistent with industry standards.  Motient Services is
in compliance  in all material  respects  with its  obligations  to pay premiums
under all such  insurance  policies.  Motient  Services has not received  notice
from,  and has no knowledge  of any threat by, any insurer  (that has issued any
insurance policy to Motient Services) that such insurer intends to deny coverage
under or cancel,  discontinue or not renew any insurance policy covering Motient
Services presently in force.

4.7.     Intellectual Property

     Schedule 4.7 to the  Disclosure  Schedule lists all  franchises,  licenses,
trademarks,  service marks,  trade names,  copyrights,  patents and applications
therefor  used,  owned or  licensed  by or  registered  in the  name of  Motient
Services and used in the Satellite  Communications  Business.  Motient  Services
owns all of the  Intellectual  Property listed on Schedule 4.7 to the Disclosure
Schedule  except  as  otherwise  indicated  on  Schedule  4.7 to the  Disclosure
Schedule,  pays no royalty to anyone with respect to any  Intellectual  Property
other than as described on Schedule 4.7 to the  Disclosure  Schedule and has the
right to bring action for the infringement of such Intellectual Property, except
where the  failure so to own or to bring such  action  would not  reasonably  be
expected  to result in a  Material  Adverse  Effect.  Motient  Services  owns or
possesses  adequate  rights to use all  Intellectual  Property  necessary to the
conduct of the Satellite  Communications Business except where failure to own or
possess  such rights  would not  reasonably  be expected to result in a Material
Adverse  Effect.  Motient  Services has no  knowledge,  and has not received any
notice to the  effect,  that the  Satellite  Communications  Business  may or is
claimed to infringe any Intellectual  Property or legally  protectable  right of
another.

                                      -13-

<PAGE>

4.8.     Debt Instruments

     Schedule 4.8 to the Disclosure  Schedule  lists all mortgages,  indentures,
notes,  guaranties  and other  Agreements  for or  relating  to  borrowed  money
(including, without limitation, conditional sales agreements and capital leases)
to which  Motient  Services  is a party,  or which have been  assumed by Motient
Services  or to which the  Subject  Assets are  subject.  Motient  Services  has
performed all the obligations  required to be performed by it to date and is not
in default in any respect under any of the foregoing, and there has not occurred
any event which (whether with or without notice,  lapse of time or the happening
or occurrence of any other event) would constitute such a default.

4.9.     Leases

     Schedule  4.9 to the  Disclosure  Schedule  lists  all  leases  used in the
Satellite  Communications  Business  under which  Motient  Services is lessee or
lessor of any asset  (including,  but not limited  to, any lease  which  Motient
Services subleases to or from another party), or holds,  manages or operates any
asset  owned by any third  party,  or under  which any  asset  owned by  Motient
Services is held, operated or managed by a third party.  Motient Services is the
owner and holder of all the leasehold  estates  purported to be granted to it by
the Documents  described on Schedule 4.9 to the  Disclosure  Schedule and is the
owner or lessee of all  equipment,  machinery  and other  Assets  thereon  or in
buildings  and  structures   thereon,  in  each  case  free  and  clear  of  all
Encumbrances  (other  than  Encumbrances  on a  third-party  landlord's  fee  or
leasehold ownership of leased or subleased property,  Encumbrances in connection
with Personal Property subject to financing leases described on Schedule 4.9 and
Encumbrances  described on Schedule 4.9). Each such lease and other Agreement is
in full force and effect and constitutes a legal,  valid and binding  obligation
of, and is legally  enforceable  against,  Motient Services,  and to the best of
Motient Services' knowledge, the respective third parties thereto and grants the
leasehold estate it purports to grant free and clear of all Encumbrances  (other
than  Encumbrances  on a third-party  landlord's  fee or leasehold  ownership of
leased or subleased property,  Encumbrances in connection with Personal Property
subject to financing leases described on Schedule 4.9 and Encumbrances described
on Schedule 4.9). Motient Services has in all respects performed all obligations
thereunder  required  to be  performed  by it to date  where the  failure  to so
perform would reasonably be expected to have a Material Adverse Effect.  Neither
Motient  Services  nor, to the best of Motient  Services'  knowledge,  any third
party is in default in any respect under any of the foregoing, and there has not
occurred any event which (whether with or without  notice,  lapse of time or the
happening or occurrence of any other event) would constitute such a default.

4.10.    Other Agreements

     Schedule  4.10 to the  Disclosure  Schedule  lists all material  Agreements
(other than those  described in Section  4.9) of Motient  Services or any of its
Affiliates connected to the operation of the Satellite  Communications  Business
(other than the Excluded Assets). Except as otherwise described on Schedule 4.10
to the Disclosure Schedule,  each such Agreement is in full force and effect and

                                      -14-

<PAGE>

constitutes a legal, valid and binding obligation of, and is legally enforceable
against,  Motient Services and, to the best of Motient Services' knowledge,  the
respective third parties thereto. Motient Services has in all respects performed
all the obligations  thereunder required to be performed by it, except where the
failure to so perform would  reasonably  be expected to have a Material  Adverse
Effect.  Neither  Motient  Services  nor,  to  the  best  of  Motient  Services'
knowledge,  any  third  party is in  default  in any  respect  under  any of the
foregoing,  and there has not occurred any event which  (whether with or without
notice,  lapse of time or the  happening or occurrence of any other event) would
constitute such a default.  Schedule 4.10 to the Disclosure  Schedule identifies
all material  Agreements (other than those described in Section 4.9) used in the
Satellite  Communications  Business to which  Motient  Services is a party or by
which Motient Services is bound that contains provisions that are triggered upon
a change of control of the Satellite Communication Business.

4.11.    Litigation; Disputes

     (a) There are no  actions,  suits,  Claims,  arbitrations,  proceedings  or
investigations pending,  threatened or reasonably anticipated against, affecting
or involving  Motient  Services,  the Satellite  Communications  Business or the
Subject Assets, or the transactions  contemplated by this Sale Agreement, at law
or in equity or admiralty, or before or by any court, arbitrator or governmental
authority,  domestic or foreign, other than as set forth on Schedule 4.11 to the
Disclosure  Schedule.  None  of  such  actions,  suits,  Claims,   arbitrations,
proceedings  or  investigations  set forth on  Schedule  4.11 to the  Disclosure
Schedule would, individually or in the aggregate, reasonably be expected to have
a Material Adverse Effect.  Motient Services is not operating under,  subject to
or in default  with respect to any order,  award,  writ,  injunction,  decree or
judgment of any court, arbitrator or governmental authority.

     (b) Except for  matters  governed by Section  4.25,  Motient  Services  has
complied  with  all  applicable  Laws of  federal,  state,  local,  and  foreign
governments   (and  all  agencies   thereof)   with  respect  to  the  Satellite
Communications  Business  and  has  complied  with  all  licenses,  permits  and
authorizations  with respect to the  Satellite  Communications  Business,  where
Motient  Services'  failure  to  comply  would be  reasonably  likely  to have a
Material  Adverse Effect.  Motient  Services has all federal,  state,  local and
foreign  governmental  licenses,  permits,   qualifications  and  authorizations
("Permits") materially necessary in the conduct of the Satellite  Communications
Business as currently conducted.  All such Permits are in full force and effect,
and no material violations have been recorded in respect of any such Permits; no
material  proceeding  is  pending  or, to the  knowledge  of  Motient  Services,
threatened  to revoke  or limit  any such  Permit;  and no such  Permit  will be
suspended,  cancelled or adversely  modified in any material respect as a result
of the execution and delivery of this Sale Agreement or the Ancillary Agreements
and the consummation of the transactions contemplated hereby or thereby.

4.12.    Labor Relations; Employees

     There  are  no  strikes,  work  stoppages,   grievance  proceedings,  union
organization  efforts or other  controversies  pending,  or, to the knowledge of
Motient  Services,  threatened  or reasonably  anticipated,  with respect to the
Satellite  Communications  Business between Motient Services and (i) any current

                                      -15-

<PAGE>

or former  employees of Motient  Services or (ii) any union or other  collective
bargaining unit representing  such employees.  Motient Services has complied and
is in  compliance  with  all  Laws  relating  to  employment  or the  workplace,
including,  without limitation,  provisions relating to wages, hours, collective
bargaining, safety and health, work authorization, equal employment opportunity,
immigration,  withholding,  unemployment  compensation,  worker's  compensation,
employee  privacy and right to know,  except  where  failure to comply with such
Laws would not, individually or in the aggregate, reasonably be expected to have
a  Material  Adverse  Effect.  There are no  collective  bargaining  agreements,
employment  agreements  between  Motient  Services and any of its employees,  or
professional  service  agreements  not  terminable  at will with  respect to the
Satellite Communications Business.

4.13.    Taxes

     (a)  Motient  Services  has timely  filed (or has had  timely  filed on its
behalf) all material Tax Returns  required by  applicable  law to be filed by it
prior to the date hereof,  and all such material Tax Returns were true,  correct
and complete in all material respects.

     (b)  Motient  Services  has paid (or has had paid on its  behalf) all Taxes
shown due with respect to Tax Returns filed prior to the date hereof;

     (c) There are no material  Encumbrances  for Taxes on any assets of Motient
Services (other than for current Taxes not yet due and payable);

     (d)  Motient  Services  has  complied  in all  material  respects  with all
applicable laws,  rules and regulations  relating to the payment and withholding
of Taxes;

     (e) Motient Services is not a party to any tax allocation, tax sharing, tax
indemnity  or similar  agreement  (whether or not in  writing),  arrangement  or
practice with respect to Taxes (including any adverse pricing agreement, closing
agreement or other agreement relating to Taxes with any authority),  except with
Motient Corporation;

     (f)  No  federal,   state,   local  or  foreign  audits  or  administrative
proceedings  are  presently  ongoing  with regard to any  material  Taxes or Tax
Returns of Motient  Services  and Motient  Services  has not  received a written
notice of any  proposed  audit or  proceeding  regarding  any  pending  audit or
proceeding.

4.14.    Restrictions and Consents

     Except as set forth on Schedule 4.14 to the Disclosure Schedule,  there are
no Agreements,  Laws or other restrictions of any kind to which Motient Services
(or any  Subject  Asset) is party or subject  that would (a) prevent or restrict
the execution,  delivery or performance of this Sale Agreement, or (b) result in
any penalty,  forfeiture,  Agreement  termination,  or  restriction  on business
operations of Newco as a result of the  execution,  delivery or  performance  of
this Sale Agreement, which would be reasonably likely to have a Material Adverse
Effect.

                                      -16-

<PAGE>

4.15.    Authorization

     The execution,  delivery and  performance by Motient  Services of this Sale
Agreement and all other Documents  contemplated  hereby,  the fulfillment of and
compliance with the respective terms and provisions hereof and thereof,  and the
consummation by Motient  Services of the  transactions  contemplated  hereby and
thereby,  (a) have been duly authorized by all necessary corporate action on the
part of  Motient  Services,  (b)  except  as set forth on  Schedule  4.15 to the
Disclosure  Schedule,  do not and will not  require  any  consent or approval of
Motient Services, any of its Affiliates or any third party which has not already
been  obtained,  (c) do not and will not conflict with, or violate any provision
of, any Law having  applicability  to Motient  Services or the  Subject  Assets,
except for such  conflicts or violations  which would not reasonably be expected
to have a Material  Adverse  Effect,  or any  provision  of the  certificate  or
articles of incorporation or bylaws of Motient Services, (d) except as set forth
on Schedule 4.15 to the Disclosure Schedule,  do not and will not conflict with,
or result in any breach of, or  constitute  a default  under (i) the  Indenture,
dated March 31, 1998,  among Motient  Holdings Inc., State Street Bank and Trust
Company and the Guarantor  named therein (the  "Indenture")  with respect to the
Series A and Series B 12 1/4% Senior  Notes Due 2008 (the "Senior  Notes"),  and
(ii) any other Agreement to which Motient  Services is a party or by which it or
any of the Subject Assets may be bound which would be reasonably  likely to have
a Material  Adverse Effect,  or (e) do not and will not result in or require the
creation or imposition of or result in the acceleration of any indebtedness,  or
of any  Encumbrance of any nature upon, or with respect to, Motient  Services or
any of the Subject  Assets now owned or hereafter  acquired by Motient  Services
which would be reasonably likely to have a Material Adverse Effect.

4.16.    Absence of Violation

     Motient  Services  has  complied  and is in full  compliance  with all Laws
applicable to the Satellite  Communications  Business, the Subject Assets or the
Assumed  Liabilities  except where  failure to so comply would not be reasonably
likely to have a Material Adverse Effect.

4.17.    Binding Obligation

     This Sale Agreement  constitutes a legal,  valid and binding  obligation of
Motient Services, enforceable in accordance with its terms; and each Document to
be executed by Motient Services pursuant hereto,  when executed and delivered in
accordance with the provisions  hereof,  shall be a valid and binding obligation
of Motient Services, enforceable in accordance with its terms.

4.18.    Financial Statement

     Motient  Services has previously  furnished to Newco the unaudited  balance
sheet  of  Motient   Services  dated  as  of  March  31,  2000  (the  "Financial
Statement"). The Financial Statement is in accordance with the books and records
of Motient  Services  and  presents  fairly the  financial  position  of Motient
Services at March 31, 2000 in all material  respects,  subject to the absence of
footnotes and to normal and customary year-end adjustments.

                                      -17-

<PAGE>

4.19.    Absence of Undisclosed Liabilities

     Except as described in the Financial Statement, there are no liabilities or
obligations  (whether  absolute or  contingent,  matured or unmatured,  known or
unknown)  of Motient  Services  which would be  required  to be  disclosed  on a
financial  statement prepared in accordance with generally  accepted  accounting
principles,  except  for those  liabilities  or  obligations  (i)  reflected  or
reserved against in the Financial Statement,  (ii) that have been incurred after
March 31, 2000 in the ordinary course of business consistent with past practice,
or (iii) that are not reasonably likely to have a Material Adverse Effect.

4.20.    Material Adverse Change

     Except as set  forth in  Section  4.20 of the  Disclosure  Schedule,  since
December  31,  1999 there has been no change,  circumstance  or event that could
reasonably be expected to result in a Material Adverse Effect or have a material
adverse effect on the transactions contemplated by this Sale Agreement.

4.21.    Assets Used in Satellite Communications Business

     The Subject  Assets  constitute  all of the Assets (other than the Excluded
Assets) used by Motient Services in the Satellite Communications Business.

4.22.    Licenses

     Motient   Services   possesses   all   licenses   issued  by  the   Federal
Communications  Commission,  and all other  licenses,  permits,  franchisers and
similar  authorizations,  that are required for the  operation of the  Satellite
Communications  Business as presently  conducted and the  ownership,  operation,
lease and  holding by Motient  Services  of the  Subject  Assets  (the  "Company
Permits").  Motient  Services  is in  compliance  with the terms of the  Company
Permits.

4.23.    Transactions with Affiliates.

     Except as set forth on Schedule 4.23 of the Disclosure Schedule,  there are
no material Agreements or transactions with any Affiliate of Motient Services.

4.24.    Employee Benefit Plans.

     Schedule  4.24 of the  Disclosure  Schedule  contains  a list of all of the
employee  benefit plans  covering the employees of the Satellite  Communications
Business.

                                      -18-

<PAGE>

4.25.    Environmental Matters.

     Except as set forth on Schedule 4.25 of the Disclosure Schedule, there are,
with respect to Motient Services, no past or present violations of Environmental
Law (as defined below), nor any actions, activities, circumstances,  conditions,
events,  incidents,  or contractual  obligations  which are reasonably likely to
give rise to any liability  which would have a Material  Adverse Effect pursuant
to any  Environmental  Law,  and Motient  Services  has not received any written
notice with respect to any of the foregoing nor is any Litigation pending or, to
the knowledge of Motient  Services,  threatened  in  connection  with any of the
foregoing.

     For purposes of this Section 4.25, capitalized terms used herein shall have
the following meanings:

     "Environmental  Laws"  shall mean all  applicable  provisions  of  federal,
state, local or foreign law (including applicable principles of common and civil
law),  statutes,   ordinances,  rules,  regulations,   published  standards  and
directives that have the force and effect of law, permits, licenses,  judgments,
writs,  injunctions,  decrees and orders  enacted,  promulgated or issued by any
Public   Authority,   and  all  indemnity   agreements  and  other   contractual
obligations,  as in effect at such date,  relating to (i) the  protection of the
environment,  including the air, surface and subsurface  soils,  surface waters,
groundwaters and natural resources,  and (ii) occupational health and safety and
exposure of persons to Hazardous Materials. Environmental Laws shall include the
Comprehensive Environmental Response,  Compensation and Liability Act, 42 U.S.C.
Sect.  9601  et seq.,  and any other laws  imposing or creating  liability  with
respect to Hazardous Materials.

     "Hazardous   Material"   shall  mean  any   substance   regulated   by  any
Environmental Law.

     "Public Authority" shall mean any supranational,  national, regional, state
or local  government  court,  governmental  agency,  authority,  board,  bureau,
instrumentality or regulatory body.

5.       REPRESENTATIONS AND WARRANTIES OF NEWCO

     Newco hereby represents and warrants to Motient Services as follows:

5.1.     Organization and Standing

     Newco is a limited liability  company duly organized,  validly existing and
in good standing  under the laws of the State of Delaware,  and has the full and
unrestricted  limited  liability company power and authority to own, operate and
lease its Assets,  to carry on its business as currently  conducted,  to execute
and deliver this Sale Agreement and to carry out the  transactions  contemplated
hereby,  except where the failure to have such limited  liability  company power
and authority would not reasonably be expected to have a material adverse effect
on the business operations,  financial condition, assets or liabilities of Newco
(a "Newco Material Adverse Effect").

                                      -19-

<PAGE>

5.2.     Authorization

     The execution, delivery and performance by Newco of this Sale Agreement and
all other Documents  contemplated hereby, the fulfillment of and compliance with
the respective terms and provisions hereof and thereof,  and the consummation by
Newco of the transactions  contemplated  hereby and thereby,  (a) have been duly
authorized by all necessary action on the part of Newco, (b) do not and will not
conflict  with,  or violate any provision  of, any Law having  applicability  to
Newco or any of its Assets,  except for such conflicts or violations which would
not, individually or in the aggregate, reasonably be expected to have a material
adverse effect on the ability of the parties to this Sale Agreement to close the
transactions  contemplated  hereby,  or  any  provision  of the  certificate  of
formation  or  operating  agreement  of Newco,  (c) do not and will not conflict
with,  or result in any breach of, or  constitute  a default  under any material
Agreement  to which  Newco is a party or by which it or any of its assets may be
bound which would be reasonably  likely to have a Newco Material Adverse Effect,
or (d) do not and will not result in or require the creation or imposition of or
result in the acceleration of any indebtedness,  or of any material  Encumbrance
upon,  or with  respect  to,  Newco or any of the assets now owned or  hereafter
acquired  by Newco  which would be  reasonably  likely to have a Newco  Material
Adverse Effect.

5.3.     Binding Obligation

     This Sale  Agreement  constitutes a valid and binding  obligation of Newco,
enforceable in accordance with its terms.  Each Document to be executed by Newco
pursuant  hereto,  when executed and delivered in accordance with the provisions
hereof,  shall be a valid  and  binding  obligation  of  Newco,  enforceable  in
accordance with its terms.

6.       CONDITIONS PRECEDENT TO OBLIGATIONS OF MOTIENT SERVICES

     The  obligations  of Motient  Services to effect the Closing 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 Motient  Services to effect the Closing,  unless such failure
was caused by, or is waived in writing by, Motient Services:

6.1.     Representations and Warranties

     The  representations  and  warranties  made by Newco in this Sale Agreement
shall be true and  complete  in all  respects  as of the date made and as of the
Closing Date.

6.2.     Performance

     Newco shall have  performed and complied in all material  respects with all
Agreements  and  conditions  required by this Sale  Agreement to be performed or
complied with by Newco prior to the Closing Date.

                                      -20-

<PAGE>

6.3.     Legal Proceedings

     No action or proceeding by or before any governmental  authority shall have
been  instituted  (and  not   subsequently   dismissed,   settled  or  otherwise
terminated) which is reasonably expected to restrain, prohibit or invalidate the
transactions  contemplated  by this Sale  Agreement,  other  than any  action or
proceeding  instituted  by or on  behalf  of  Motient  Services  or  any  of its
Affiliates.

6.4.     Hart-Scott-Rodino

     All applicable waiting periods under Hart-Scott-Rodino shall have expired.

6.5.     Newco's Certificate

     Newco shall have delivered to Motient  Services a certificate,  dated as of
the Closing Date and executed by a senior  officer of Newco,  certifying  to the
fulfillment of the conditions set forth in Sections 6.1 and 6.3.

6.6.     Federal Communications Commission Consent

     All  applicable  consents  and  approvals  from the Federal  Communications
Commission  (the  "FCC")  necessary  for the  consummation  of the  transactions
described hereunder shall have been obtained, including the receipt of the Final
FCC Order.

6.7.     Other Consents

     Newco and Motient  Services shall have received all  governmental  consents
and  approvals,  in each case,  necessary in  connection  with the  transactions
contemplated hereby.

7.       CONDITIONS PRECEDENT TO OBLIGATIONS OF NEWCO

     The  obligations  of  Newco  to  effect  the  Closing  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 Newco to effect the Closing,  unless such failure was caused by,
or is agreed to in writing, by Newco:

7.1.     Representations and Warranties

     The  representations  and warranties made by Motient  Services in this Sale
Agreement and the statements  contained in the Disclosure Schedule shall be true
and complete in all respects when made.

     Each of the  representations and warranties made pursuant to Section 3.8 as
of the Update Date shall be true and correct as of the Closing as though made at
the  Closing,  except for  changes  permitted  by or  consistent  with this Sale
Agreement.  Newco  shall have  received  a  certificate  of the chief  executive
officer or chief financial officer of Motient Services to the foregoing effect.

                                      -21-

<PAGE>

7.2.     Performance

     Motient Services shall have performed and complied in all material respects
with all  Agreements  and  conditions  required  by this  Sale  Agreement  to be
performed or complied with by Motient Services prior to the Closing Date.

7.3.     Legal Proceedings

     No action or proceeding by or before any governmental  authority shall have
been  instituted  (and  not   subsequently   settled,   dismissed  or  otherwise
terminated) which is reasonably expected to restrain, prohibit or invalidate the
transactions  contemplated  by this  Sale  Agreement  other  than an  action  or
proceeding instituted by Newco.

7.4.     Hart-Scott-Rodino

     All applicable waiting periods under Hart-Scott-Rodino shall have expired.

7.5.     Officer's Certificate

     Motient  Services shall have delivered to Newco a certificate,  dated as of
the  Closing  Date  and  executed  by a  senior  officer  of  Motient  Services,
certifying  to the  fulfillment  of the  conditions  specified  in Sections  7.1
through 7.3 and 7.8.

7.6.     Federal Communications Commission Consent

     All  applicable  consents  and  approvals  from the FCC  necessary  for the
consummation of the transactions  described  hereunder shall have been obtained,
including the receipt of the Final FCC Order.

7.7.     Financing

     Newco shall have completed financing  arrangements on terms satisfactory to
it in its sole  discretion  providing it with access to funds  sufficient to pay
the balance of the Purchase Price.

7.8.     Other Consents

     Motient   Services  and  Newco  shall  have   received  all   governmental,
shareholder  and third party  consents and approvals  (including the consents of
lenders),  in each case,  necessary  or, in the  reasonable  judgment  of Newco,
desirable in connection with the transactions contemplated hereby.

                                      -22-

<PAGE>

7.9.     No Material Adverse Effect

     No Material  Adverse  Effect  shall have  occurred,  nor shall any event or
events have occurred which would be reasonably likely to have a Material Adverse
Effect,  with  respect  to  Motient  Services  or the  Satellite  Communications
Business.

7.10.    Revocation of Notice

     If the  Closing  shall not occur due to a failure of any of the  conditions
listed in this Section 7, then the Notice shall be deemed revoked and the Notice
can be given again at any time prior to the Outside Date.

8.       Closing

8.1.     Deliveries by Motient Services

     At the Closing, Motient Services shall deliver to Newco the following:

     (a) a certified copy of the  resolutions  adopted by the Board of Directors
of Motient Services on or prior to the date hereof authorizing the Closing;

     (b)  certificates  of incumbency  and specimen  signatures of the signatory
officers of Motient Services;

     (c) the certificate required pursuant to Section 7.5 hereof;

     (d) a  bill  of  sale  and  limited  assignment  and  assumption  agreement
substantially  in the form attached as Exhibit B, and such other  instruments of
transfer  as Newco  shall  reasonably  require to transfer to Newco title to the
Subject  Assets  free and clear of all  Claims and  Encumbrances  other than the
Assumed  Liabilities and to cause Newco to assume the Assumed  Liabilities  (the
"Transfer Instruments");

     (e) the certificate required pursuant to Section 7.1 hereof;

     (f) an opinion  of Hogan & Hartson  L.L.P.,  counsel  to Motient  Services,
dated as of the Closing Date, reasonably acceptable to Newco; and

     (g) such other Documents as Newco may reasonably request.

8.2.     Deliveries by Newco

     At the Closing, Newco shall deliver the following:

     (a) a wire  transfer  of the  balance  of the  Purchase  Price  payable  in
accordance with Section 2.2;

                                      -23-

<PAGE>

     (b) a certified copy of the  resolutions  adopted by the Board of Directors
of Newco authorizing the Closing;

     (c) the certificate required by Section 6.5;

     (d) the  Transfer  Instruments  (to the extent  required  to be executed by
Newco); and

     (e) such other Documents as Motient Services may reasonably request.

8.3.     Transferred Employees

     (a) As used in this Agreement,  "Transferred Employees" means the employees
of the  Satellite  Communications  Business  which  shall  be  identified  on an
"Employee  Schedule" to be delivered by Motient  Services to Newco on the Update
Date.

     (b) Newco shall offer employment to all the Transferred Employees effective
as of the day  following  the Closing Date at the same salary or hourly wage set
forth in the Employee  Schedule,  subject to Newco's right to terminate any such
Transferred  Employee,  in accordance with applicable  Laws, at any time with or
without cause, for any reason or no reason at all.

     (c) During the period  commencing  as of the Closing Date and ending on the
first (1st) anniversary thereof, Newco shall cause the Transferred Employees who
accept such  employment  offer (the  "Accepting  Employees") to be provided with
compensation  and employee  benefit plans (excluding stock option or other plans
involving the potential issuance of securities of Motient  Corporation) which in
the aggregate are not  materially  less  favorable  than those  provided to such
employees  by  Motient  Services  and its  Affiliates  immediately  prior to the
Closing Date, to the extent  permitted under  applicable Laws. The provisions of
this  Section  8.3 shall not  create in any  Transferred  Employee  or any other
current or former  employee  of Motient  Services or any of its  Affiliates  any
rights to employment or continued employment with Newco, Motient Services or any
of their  respective  Affiliates or any right to specific terms or conditions of
employment. Promptly following the Closing Date, Motient Services shall transfer
to Newco all personnel files pertaining to the Accepting Employees.

     (d) Newco  shall  provide  each  Accepting  Employee  full  credit for such
Accepting  Employee's  service  with  Motient  Services  or  its  Affiliates  or
predecessors  for purposes of  eligibility,  vesting and benefit accrual (except
for benefit  accruals under any defined benefit pension plan) under the employee
benefit  plans  or  arrangements  of Newco in  which  such  Accepting  Employees
participate for such Accepting  Employee's  service with Motient Services or its
Affiliates, to the same extent recognized under similar plans or arrangements of
Motient Services or its Affiliates immediately prior to the Closing.

     (e) Newco shall (i) waive all  limitations  as to  preexisting  conditions,
exclusions  and waiting  periods  with  respect to  participation  and  coverage
requirements  applicable to any  Accepting  Employee  under any welfare  benefit
plans in which such Accepting Employees may be eligible to participate after the

                                      -24-

<PAGE>

Closing,  other than  limitations or waiting  periods that are already in effect
with respect to such  Accepting  Employee and that have not been satisfied as of
the Closing  under any  welfare  plan  maintained  for such  Accepting  Employee
immediately prior to the Closing,  and (ii) provide each Accepting Employee with
credit for any  co-payments  and  deductibles  paid prior to the  Closing  under
welfare plans of Motient  Services or any of its Affiliates for the plan year in
which  the  Closing   occurs  in  satisfying   any   applicable   deductible  or
out-of-pocket  requirements  under any welfare plans that such Accepted Employee
is eligible to participate in after the Closing.

     (f) Following the Closing,  Newco shall honor and maintain all vacation and
other  leave  earned  or  accrued  by,  but not  taken by or paid  to,  Accepted
Employees  through the Closing (as  calculated or determined  under  policies or
plans in effect immediately prior to the Closing). The preceding sentence to the
contrary  notwithstanding,  nothing set forth  herein  shall impair or otherwise
affect the rights of Newco or its Affiliates to amend,  suspend or terminate any
such  agreement,  policy or plan in accordance  with its terms as in effect from
time to time.

     (g) Each of Motient  Services and Newco shall provide any  notifications to
its  respective  employees  (including,  in the  case of  Newco,  the  Accepting
Employees and, in the case of Motient Services, Transferred Employees who do not
become Accepting Employees) required under the Workers Adjustment and Retraining
Notification  Act (the "WARN Act") and shall bear any liabilities  arising under
the WARN Act with respect to such employees.

     (h) With respect to each  Accepting  Employee,  Newco hereby agrees to give
Motient  Services  notice  of  the  termination  of  such  Accepting  Employee's
employment  with Newco within 30 days of the date thereof,  and provide  Motient
Services with such  information  with respect thereto as Motient  Services shall
reasonably  request to enable it to determine if such event would give rise to a
right of distribution to such Accepting  Employee under Motient Services' 401(k)
plan.

8.4.     Transitional Matters

     (a) The parties  acknowledge that a transition period from the Closing Date
until the date 12 months immediately following the Closing Date (the "Transition
Period") is required in order to allow  Motient  Services and its  Affiliates to
relocate to another  facility  and to provide  Newco with  certain  transitional
services as described in Section 8.5 below.

     (b)  Motient  Services  and  Newco  hereby  agree  to use all  commercially
reasonable  efforts to obtain the Landlord's  consent to the transfer of Motient
Services'  rights and obligations  under the Lease to Newco on the Closing Date.
Newco and Motient Services shall negotiate in good faith the terms of a sublease
or other  arrangement to provide  Motient  Services and its Affiliates  with the
right to use and  occupy,  during the  Transition  Period,  that  portion of the
Reston Facility used by Motient Services and its Affiliates for their respective
businesses (other than the Satellite  Communications Business) immediately prior

                                      -25-

<PAGE>

to the  Closing.  In the event that  Motient  Services  is unable to transfer or
otherwise assign its rights and obligations under the Lease to Newco,  Newco and
Motient  Services shall negotiate in good faith the terms of a sublease or other
arrangement  to provide  Newco with the right to use and occupy that  portion of
the Reston  Facility  during the Transition  Period used by Motient  Services to
conduct the Satellite  Communications Business immediately prior to the Closing.
The parties  agree that in either case the rent and other  actual  out-of-pocket
costs  associated  with the Lease shall be shared pro rata based on the parties'
actual usage of the Reston Facility measured in square feet.

8.5.     Shared Assets; Parent Guaranties

     (a) The  parties  acknowledge  that as of the  date  hereof  (and as of the
Closing  Date)  that  there  are  certain   Assets  and  Agreements  of  Motient
Corporation  and its  Subsidiaries,  which  are  listed on  Schedule  8.5 to the
Disclosure  Schedule,  that are used by Motient  Services in connection with its
Satellite  Communications  Business that will not be part of the Subject Assets,
but will remain with  Motient  Corporation  and its  Subsidiaries  (the  "Shared
Assets").  The  parties  agree to  cooperate  in good faith so that such  Shared
Assets can reasonably be divided or, if such a division is not possible,  shared
in a way so that such Shared Assets can  reasonably be used by both (i) Newco in
connection  with  the  Satellite   Communications  Business,  and  (ii)  Motient
Corporation and its subsidiaries in connection with their respective  businesses
(excluding  the  Satellite  Communications   Business).   Without  limiting  the
generality of the foregoing, on the Closing Date, Motient Services shall provide
Newco with  access to, and use of (A) the  telephones,  facsimile  machines  and
computers at the Reston Facility then used by the Accepting  Employees for their
intended and usual  purpose in  connection  with the  operation of the Satellite
Communications  Business  until the last day of the  Transition  Period  and (B)
Motient  Services'  computer  network and programs for  accounting  applications
until the earlier of (i) Newco's  installation of an autonomous computer network
for accounting purposes and (ii) the last day of the Transition Period.  Motient
Services  and Newco shall  negotiate in good faith to  equitably  apportion  the
costs and liabilities  associated  with the shared use or division,  as the case
may be, of such Assets or Agreements, and, if appropriate, enter into transition
services  agreement  which  shall  provide  for the  foregoing  and  such  other
transition services as the parties shall in good faith agree.

     (b) The  parties  agree to use all  commercially  reasonable  efforts  (but
without any obligation to expend funds) so that the  guaranties  made by Motient
Corporation and its Affiliates for the benefit of Motient  Services  relating to
the Subject Assets and the Assumed Liabilities (the "Parent Guaranties") will be
terminated or otherwise released on or prior to the Closing, or if not possible,
as soon as practicable  thereafter.  In the event that the Parent Guaranties are
not terminated by the Closing,  Newco shall indemnify,  defend and hold harmless
Motient  Services  from and  against  all  Losses of  Motient  Services  and its
Affiliates which (i) arise under any unreleased Parent Guaranty,  (ii) relate to
any Assumed Liability,  and (iii) arise out of the ownership or operation of the
Satellite  Communication  Business following the Closing;  without regard to the
provisions of Article 9.

                                      -26-

<PAGE>

8.6.     Motient Resale Of Newco Products And Services

     Following  the Closing,  to the extent the  ordinary  course of business of
Newco  includes  marketing  its products or services  through  resellers,  Newco
shall,  at the  request  of  Motient  Corporation  or  any  of its  wholly-owned
subsidiaries  (including  Motient  Communications,  Inc.), offer to enter into a
Newco Standard  Reseller  Arrangement with such requesting  party, on terms that
are, on the whole,  at least as  favorable  as the terms Newco then offers under
any Newco  Standard  Reseller  Arrangement to any reseller that has purchased or
committed  to purchase a similar  volume of  products  or  services  from Newco,
provided  that this  Section  8.7 shall not require  Newco to offer  products or
services to such requesting  party that it does not offer for resale or to enter
into any  arrangement  if Newco  determines in good faith that such  arrangement
would prevent or significantly  hinder its ability to capitalize upon a material
business  opportunity.  As  used  herein,  the  term  "Newco  Standard  Reseller
Arrangement"  shall mean an  agreement in the form used by Newco in the ordinary
course  of  its  business  with  third  parties  whose  only  material  business
relationship  with Newco  involves  reselling  Newco products or services in the
ordinary  course of  business.  Unless  otherwise  agreed  by  Newco,  the Newco
Standard  Reseller  Arrangement  offered by Newco  pursuant  hereto shall not be
required  to have a term  that  extends  beyond  the  third  anniversary  of the
Closing.

8.7.     Use of Proceeds

     Motient  Services  covenants and agrees to use and apply the Purchase Price
consistent  with  any  restrictions  set  forth  in  any  loan  documents,  bank
agreements, indenture or similar documents applicable to Motient Services or its
Affiliates.

8.8.     Insurance Proceeds from Satellite Failure

     (a) In the event that prior to Closing, an event occurs causing the full or
partial  failure  of the  Satellite  (a  "Satellite  Casualty  Event"),  Motient
Services  shall  send  written  notice to Newco  within ten (10)  business  days
describing  the  Satellite  Casualty  Event  in  reasonable  detail,   including
information  as to whether the casualty is or may be covered by  insurance  (the
"Casualty  Notice").  As soon as possible after  ascertaining  whether or not it
will be  required to apply any  insurance  proceeds  relating  to the  Satellite
Casualty  Event (the  "Insurance  Proceeds") to the  reduction of  indebtedness,
Motient  Services  shall  notify  Newco  as to  such  requirement  (the  "Lender
Notice").  The Outside Date shall be automatically extended to the date which is
60 days after the date of receipt by Newco of the Lender  Notice.  If the Lender
Notice  shall state that the  Insurance  Proceeds are not required to be paid in
accordance  with Motient  Corporation's  or any of its  subsidiaries'  financing
agreements and, therefore,  Motient Services is entitled to retain the Insurance
Proceeds, then the parties hereto shall proceed on the same terms and conditions
as  otherwise  provided in this Sale  Agreement  (including  with respect to the
Purchase  Price)(without  application  of clause (b) of this Section 8.8) except
that the Insurance Proceeds shall be deemed to be part of the Subject Assets and
in the event of a total  failure  where  Motient  Services  no  longer  owns the
Satellite,  the Satellite shall not be part of the Subject Assets. If the Lender
Notice  shall  state that the  Insurance  Proceeds  are  required  to be paid in
accordance  with Motient  Corporation's  or any of its  subsidiaries'  financing
agreements,  then the Outside Date shall be  automatically  extended to the date
which is 60 days after the date on which Motient  Services  notifies  Newco (the
"Insurance Notice") that it and the insurance carrier finally resolve the amount
of the Insurance Proceeds.

                                      -27-

<PAGE>

     (b) The Insurance Notice shall contain Motient Services' election to either
(i) reduce the Purchase Price by an amount equal to the Insurance  Proceeds,  or
(ii) proceed on the same terms and conditions as otherwise provided in this Sale
Agreement  (including  with  respect to the Purchase  Price) with the  Insurance
Proceeds (and in the event of a total  failure where Motient  Services no longer
owns the Satellite,  the  Satellite) to be deemed  Excluded  Assets.  If Motient
Services  selects  option (i), then this  Agreement  shall  continue on the same
terms and conditions except for the reduction in the Purchase Price as set forth
in clause (i). If Motient  Services selects option (ii), then Newco can elect to
either (y) proceed on the same terms and  conditions  as  otherwise  provided in
this Sale  Agreement  (including  with respect to the  Purchase  Price) with the
Insurance  Proceeds (and in the event of a total failure where Motient  Services
no longer owns the Satellite,  the Satellite) to be deemed Excluded  Assets,  or
(z)  terminate  this Sale  Agreement  and receive an  irrevocable  refund in the
amount  equal to the  Deposit  and the R&D Fee  (i.e.,  a total of $44  million)
subject to  reduction  pursuant to 8.11 hereof  (the  "Refund"),  in which case,
Motient  Services  shall be  obligated  to pay such amount to Newco within sixty
(60) days of Newco's election.

     (c) Notwithstanding the foregoing,  at any time prior to earlier of (i) the
Outside  Date (as it may be  extended  pursuant  to this  Section  8.8) and (ii)
payment of the Refund pursuant to Section 8.8(b)(z),  Newco may elect to proceed
on the terms otherwise specified in this Sale Agreement  (including with respect
to the Purchase Price) with the Insurance  Proceeds (and in the event of a total
failure where Motient  Services no longer owns the Satellite,  the Satellite) to
be deemed Excluded Assets.

     (d) So long as Motient  Services  complies with clauses (a) ,(b) and (c) of
this  Section 8.8,  including  refunding  any amount due to Newco under  section
8.8(b)(z),   Motient  Corporation  and  its  direct  and  indirect  subsidiaries
(including Motient Services) shall have no further liability with respect to the
failure of the  Satellite  under this Sale  Agreement,  the R&D Agreement or any
other  Agreement,  and Newco shall have be deemed to have waived its rights,  if
any, with respect to any indemnity or other remedy from Motient Services related
to the failure of the Satellite.

8.9.     Sale of Motient Services or the Satellite Communications Business

     (a) In the event that  following the first  anniversary  of the date hereof
and prior to  earlier  of (i) the  termination  of this Sale  Agreement  and the
Closing, Motient Corporation or Motient Services shall receive a bona fide offer
that Motient Services reasonably believes is capable of being consummated on the
terms proposed,  and that Motient  Corporation or Motient  Services  proposes to
accept (an "Offer") from any unaffiliated third party (the "Offeror") to acquire
all or substantially  all of the assets of, or otherwise a substantial  interest
(by means of a stock purchase,  merger,  business  combination or otherwise) in,
Motient  Services  or  the  Satellite  Communications  Business,  other  than  a
transaction  of the  type  contemplated  by  Section  7.4(b)  of the  Investment
Agreement,  Motient  Services shall give written notice (the "Offer Notice," the

                                      -28-

<PAGE>

date of receipt of which is referred to as the "Offer  Notice Date") to Newco of
such Offer, which notice shall contain a reasonably detailed  description of the
proposed transaction, including the identity of the Offeror (including any known
affiliates),  a  description  of the  consideration  to be  received  in respect
thereof and a description of all the material terms of the Offer. Until the 60th
day after the Offer Notice Date, no action shall be taken by Motient Corporation
or Motient  Services or any of their Affiliates to accept the Offer or to create
any  obligation to the Offeror in respect of the Offer.  If, on or prior to such
60th day, Newco delivers the Notice (as defined in Section 3.1 hereof),  Motient
Corporation  and Motient  Services  shall  continue to refrain from pursuing the
Offer and shall proceed in accordance with the terms of this Sale Agreement.

     (b) In the event that Newco shall not have  delivered  the Notice  prior to
the 60th day after the Offer Notice Date,  Motient Services may accept the Offer
and consummate  the  transactions  contemplated  thereby on terms not materially
less favorable to Motient  Services than the terms contained in the Offer Notice
and this Sale  Agreement  shall be deemed to be  terminated  pursuant to Section
10.1 hereof as of the  closing of the  transactions  contemplated  by the Offer;
provided that Motient  Services shall give Newco not more than ten nor less than
five business days notice of the closing of the transactions contemplated by the
Offer (the "Offer Closing  Notice Date"),  and within three business days of the
Offer Closing Notice Date, Newco may notify Motient Services as to whether Newco
will be  liquidated  in  accordance  with Section  13.1(c) of the LLC  Operating
Agreement,  in which case Motient  Services may not consummate the  transactions
contemplated  by the Offer  unless  prior  thereto or  simultaneously  therewith
Motient  Services  shall  irrevocably  refund  to Newco an  amount  equal to the
Refund.

8.10.    Loss of FCC Licenses

     In the event that prior to Closing,  any of the Licenses in effect with the
Federal Communications Commission lapse, terminate or are not renewed so that it
is  commercially  unreasonable  to continue the business of Motient  Services as
currently conducted, then Motient Services shall send written notice to Newco no
later than ten (10) business days  following the date Motient  Services  becomes
aware of any such lapse,  termination  or  non-renewal.  Newco at its option can
elect to (i) proceed on the same terms and  conditions as otherwise  provided in
this Sale Agreement  (including  with respect to the Purchase Price) except that
any such license that lapses,  terminates  or is not renewed shall not be deemed
part of the Licenses (and therefore,  not part of the Subject  Assets),  or (ii)
terminate  this Sale  Agreement and receive an  irrevocable  refund of an amount
equal to the Refund,  in which case,  Motient Services shall be obligated to pay
such  amount to Newco  within  sixty (60) days of Newco's  election.  So long as
Motient Services complies with this Section 8.10, including refunding any amount
due to Newco under clause (ii) of this Section 8.10, Motient Corporation and its
direct and indirect  subsidiaries  (including  Motient  Services)  shall have no
further  liability with respect to any such Licenses under this Sale  Agreement,
the R&D Agreement or any other  Agreement and Newco shall have be deemed to have
waived its rights,  if any,  with respect to any  indemnity or other remedy from
Motient  Services  related to such lapse,  termination  or non-renewal of any of
such Licenses.

                                      -29-

<PAGE>

8.11.    Reduction in the Refund Amount

     To the extent that any one or more  Investors (as defined in the Investment
Agreement) has effected or exercised its right to effect (which election has not
been revoked) a Parent  Conversion (as defined in the  Investment  Agreement) at
the time the Refund is to be irrevocably  paid,  the $44 million  required to be
paid by Motient  Services  to Newco as a refund of the  Deposit  and the R&D Fee
pursuant to Sections 8.8(b), 8.9(b) or 8.10 hereof shall be reduced by an amount
equal  to $44  million  multiplied  by the  result  of (a)  the  total  Investor
Interests (as defined in the  Investment  Agreement) of such Investor which have
effected  Parent  Conversions  immediately  prior  to such  Parent  Conversions,
divided by (b) the total  Investor  Interests of all the  Investors  immediately
prior to such Parent Conversions.  (By way of illustration only, if one Investor
had effected a Parent Conversion and owned a 6.67% Investor Interest immediately
prior to the Parent Conversion, the refund of the Deposit and the R&D Fee due to
Newco would be reduced by $14.67 million (which number is $44 million multiplied
by .3335 (6.67/20 = .3335)).

9.       SURVIVAL OF REPRESENTATIONS; INDEMNIFICATION; REMEDIES

9.1.     Survival of Representations

     All  representations  and  warranties  made by in or  pursuant to this Sale
Agreement  and in or  pursuant to the  Ancillary  Agreements  shall  survive the
Closing  until two years  after the date made  (except  to the  extent  that the
representations  and  warranties set forth in Sections 4.3 and 4.15 apply to the
Indenture,   such   representations  and  warranties  shall  survive  until  the
expiration  of the statute of  limitations  applicable to any claims made by the
holders  of  the  Senior  Notes),  and  shall  in no  way  be  affected  by  any
investigation or knowledge of the subject matter thereof made by or on behalf of
Newco.  If the Closing shall occur,  indemnification  pursuant to this Article 9
shall be the exclusive remedy for any breach of  representations  and warranties
or of any  covenant or  Agreement  in this Sale  Agreement  which  survives  the
Closing by either party or any other matter pertaining to this Sale Agreement or
the  transactions  contemplated  hereby,  other than  Claims  relating  to other
written Agreements between the parties and Claims relating to fraud or violation
of securities  laws;  provided that nothing in Article 9 shall prevent any party
from obtaining  equitable  relief in order to require the other party to perform
its obligations hereunder.

9.2.     Agreement of Motient Services to Indemnify

     From and after the  Closing,  Motient  Services  shall  indemnify  and hold
harmless Newco from and against all damages,  losses,  claims,  liabilities  and
obligations,  costs and expenses (including  attorneys' fees) ("Losses") arising
in any way out of or  related  to (i) the  breach  by  Motient  Services  of any
representation  or warranty made by Motient  Services in this Sale  Agreement or

                                      -30-

<PAGE>

any Ancillary  Agreement or in any in any document  delivered pursuant hereto or
thereto,  (ii) the breach by  Motient  Services  of any  covenant  or  agreement
contained  herein  or  any  Ancillary  Agreement  or in any  document  delivered
pursuant  hereto or thereto,  or (iii)  liabilities  of Motient  Services or its
Affiliates which are not Assumed Liabilities.  For purposes of this Section 9.2,
the terms  "material"  and  "Material  Adverse  Effect",  and other  materiality
qualifiers in the  representations  and  warranties  contained  herein or in the
Ancillary  Agreements and in any documents delivered pursuant hereto or thereto,
shall be deemed to refer to matters, and groups of related matters,  that have a
financial or economic  impact,  or are capable of having a financial or economic
impact,  of $100,000 or more.  For purposes of the foregoing  sentence,  matters
shall be considered to be within a "group of related  matters" if they relate to
any given  Section of the  representations  and  warranties.  (For  purposes  of
illustration  only,  Section  4.19  would be deemed to be  breached  if  Motient
Services  had failed to  disclose a  liability  of $25,000  and a  liability  of
$90,000, but not if Motient Services had failed to disclose seven liabilities of
$10,000 each.).

9.3.     No Duplication of Remedies

     To the  extent  any  party may have more  than one  remedy  for any  Losses
incurred by it, it may pursue all  available  remedies  but in no event shall be
entitled to collect and retain any amount hereunder in excess of its Losses.

9.4.     Agreement of Newco to Indemnify

     From and after the Closing, Newco shall indemnify and hold harmless Motient
Services from and against all Losses arising in any way out of or related to (i)
the breach by Newco of any representation or warranty made by Newco in this Sale
Agreement  or in any document  delivered  pursuant  hereto or thereto,  (ii) the
breach by Newco of any covenant or agreement contained herein or in any document
delivered pursuant hereto or thereto, or (iii) the Assumed Liabilities.

9.5.     Notice of Claims.

     All claims for  indemnification  hereunder  shall be resolved in accordance
with the following procedures:

     (i) If the party  seeking  indemnification  (the  "Indemnified  Party") has
incurred or reasonably  believes that it may incur any Losses,  it shall deliver
promptly written notice to the indemnifying  party (the  "Indemnifying  Party"),
setting  forth the  nature  and amount of the  Losses or  potential  Losses,  if
possible, and further referencing the sections of this Agreement or in any other
document delivered pursuant hereto upon which the claim for  indemnification for
such Losses is based (a "Claim Notice"). If an Indemnified Party receives notice
of a third-party claim for which it intends to seek  indemnification  hereunder,
it shall give the  Indemnifying  Party written notice of such claim, so that the
Indemnifying  Party's  defense of such claim under this  Agreement may be timely
instituted.  The failure by an Indemnified  Party to provide such written notice
shall not  constitute  a waiver of the  Indemnified  Party's  right to indemnity
unless such failure has prejudiced the  Indemnifying  Party's  ability to defend
such claim, and then only to the extent of such prejudice.

                                      -31-

<PAGE>

     (ii) If, after receiving a Claim Notice,  the Indemnifying Party desires to
dispute such claim or the amount  claimed in the Claim Notice,  it shall deliver
to the  Indemnified  Party a written  objection to such claim or payment setting
forth the basis for  disputing  such  claim or  payment.  Such  notice  shall be
delivered  within  thirty (30) days after the date the Claim  Notice to which it
relates is received  by the  Indemnifying  Party.  If no such notice is received
within the aforementioned 30-day period, the Indemnified Party shall be entitled
to payment for such Losses from the  Indemnifying  Party within ten (10) days of
the end of such 30-day objection period.

     (iii) If the Indemnifying  Party shall agree that it is responsible for all
amounts that may be recovered in connection with a third-party claim,  action or
suit (including waiving any deductible or limit that might otherwise apply under
this Article 9) and is  financially  capable of satisfying  its  indemnification
obligations,  the Indemnifying Party shall have the right to conduct and control
through  counsel  of  its  own  choosing,  which  counsel  shall  be  reasonably
acceptable to the  Indemnified  Party,  any third-party  claim,  action or suit;
provided,  that the  Indemnifying  Party  diligently  contests  and defends such
claim. The Indemnified  Party shall be entitled at any time, at its own cost and
expense  (except  that such cost and expense  shall be paid by the  Indemnifying
Party if the Indemnified Party reasonably determines that the Indemnifying Party
is not adequately  representing  or, because of a conflict of interest,  may not
adequately  represent the interests of the Indemnified  Party) to participate in
such defense and to be represented by attorneys of its choosing. Except with the
prior written  consent of the Indemnified  Party no  Indemnifying  Party, in the
defense of such claim or  litigation,  shall consent to entry of any judgment or
order,  interim or  otherwise,  or enter into any  settlement  that provides for
injunctive or other  nonmonetary  relief affecting the Indemnified Party or that
does not include as an unconditional term thereof the giving by each claimant or
plaintiff to such Indemnified Party of a release from all liability with respect
to such claim or litigation.

     (iv) In the  event  that the  Indemnifying  Party  does not elect to defend
against any third-party  claim,  the  Indemnified  Party may defend against such
claim in such manner as it may deem appropriate and the Indemnifying Party shall
be liable for any legal  expenses  reasonably  incurred in connection  with such
defense;  provided, that the Indemnified Party shall not, without the consent of
the Indemnifying Party, which consent shall not be unreasonably withheld, settle
or consent to the entry of judgment with respect to such third-party claim.

     (v) In the event of any claim by a third  party,  the parties  hereto agree
that they will cooperate fully with each other in connection with the defense or
settlement of such matter.

9.6.     Limitations on Amounts

     The  Indemnifying  Party  shall not be  obligated  to pay any  amounts  for
indemnification  under  this  Article  9  until  the  aggregate  indemnification

                                      -32-

<PAGE>

obligation of such  Indemnifying  Party  hereunder (and under the R&D Agreement)
exceeds  $500,000,  whereupon  the  Indemnifying  Party  shall be liable for all
amounts  for  which   indemnification  may  be  sought  which  exceed  $500,000.
Notwithstanding  the  foregoing,  in no event shall the  aggregate  liability of
Motient  Services to Newco  exceed the  Purchase  Price (to the extent  actually
paid) plus the R&D Fee (the "Cap"), except in the case of (i) a fraud or willful
breach  by  Motient  Services,   (ii)  a  breach  by  Motient  Services  of  the
representations  and  warranties  contained  in Sections 4.3 or 4.15 hereof with
respect  to the  Indenture,  (iv)  liabilities  with  respect  to the  Satellite
Communications  Business  accruing  prior to the  Closing  that are not  Assumed
Liabilities.  For purposes of calculating the Cap, all amounts received by Newco
for Losses under the R&D Agreement and any Agreements  delivered pursuant hereto
shall be included in calculating the Cap.

9.7.     Force Majeure

     Notwithstanding  any other  provision of this  Article 9,  neither  Motient
Services nor Newco shall be liable for any failure of  performance  of the terms
of this  Agreement  due solely to acts of God,  fires,  floods or other  natural
catastrophes;  national  emergencies,  insurrections,  riots or  wars;  strikes,
lockouts,  work  stoppages  or other labor  difficulties  beyond  such  parties'
reasonable control.

9.8.     Subrogation

     If any indemnified party receives any payment or other indemnification from
an  indemnifying  party with  respect to any Claim or demand by any third  party
against the indemnified party, the indemnifying party shall be subrogated to the
extent of such  payment  or  indemnification  to all  rights in  respect  of the
subject matter of such Claim to which the indemnified party may be entitled,  to
institute appropriate action for the recovery thereof, and the indemnified party
agrees to  provide  reasonable  levels of  assistance  and  cooperation  to such
subrogated party, in enforcing such rights.

10.      TERMINATION

10.1.    Termination

     Subject to the provisions of Sections 10.2 hereof, this Sale Agreement may,
by written  notice  given at or prior to the  Closing in the manner  hereinafter
provided, be terminated:

     (a) at any time  prior to the  Closing  by mutual  written  consent  of the
parties hereto;

     (b) pursuant to Section 8.8, 8.9 or 8.10 hereof; or

     (c) if the Notice (as defined in Section 3.1 hereof) has not been delivered
to Motient Services on or prior to the Outside Date.

                                      -33-

<PAGE>

10.2.    Effect of Termination

     In the event this Sale  Agreement is terminated as provided in this Section
10, this Sale Agreement shall  forthwith be of no further force and effect,  and
the parties shall be released from all future obligations  hereunder;  provided,
however,  that (i) the  termination  shall  not  relieve  any  party  hereto  of
liability  for any breach of this Sale  Agreement,  (ii) Newco shall  return all
Documents  provided by Motient Services to Newco pursuant to this Sale Agreement
and (iii) the  indemnification  obligations set forth in Sections 3.7.1, 9.2 and
9.4 and the obligations set forth in Sections 3.4 and 11.3 shall survive. If the
Closing  shall not occur,  in no event shall Newco be liable for any amount over
and above the Deposit and the R&D Fee.

11.      MISCELLANEOUS

11.1.    Additional Actions and Documents

     Each party hereto hereby agrees that, from time to time, whether before, at
or after the  Closing,  such party  will 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,
intents, terms and conditions of this Sale Agreement.

11.2.    No Brokers

     Each party  hereto  represents  and  warrants  to the other party that such
party  has not  engaged  any  broker,  finder  or agent in  connection  with the
transactions  contemplated  by this  Sale  Agreement  that will give rise to 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 Sale
Agreement for which Motient  Services or Newco will be  responsible.  Each party
hereto  agrees to  indemnify,  defend and hold harmless the other party from and
against  any and all  Claims  asserted  against  such party for any such fees or
commissions  by any persons  purporting to act or to have acted for or on behalf
of the indemnifying party.

11.3.    Expenses

     Subject to the  indemnity  provisions of Article 9, each party hereto shall
pay its own  expenses  incident  to this  Sale  Agreement  and the  transactions
contemplated   hereunder,   including   all  legal  and   accounting   fees  and
disbursements. Each party shall pay any Hart-Scott-Rodino filing fees payable in
connection with any Hart-Scott-Rodino filing required to be made by such party.

                                      -34-

<PAGE>

11.4.    Assignment

     Motient  Services  shall not assign its rights and  obligations  under this
Sale Agreement,  in whole or in part,  whether by operation of law or otherwise,
without the prior  written  consent of Newco.  Newco shall not assign its rights
and  obligations  under  this Sale  Agreement,  in whole or in part,  whether by
operation of law or otherwise,  unless the assignee agrees to be bound by all of
the terms and conditions  hereof  applicable to Newco hereunder.  Any assignment
contrary  to the  terms of this  Section  11.4  shall be null and void and of no
force and effect.  In no event shall the assignment by Motient Services or Newco
of such party's  respective  rights or  obligations  under this Sale  Agreement,
whether  before,  at or after the Closing,  release such party from such party's
respective liabilities and obligations hereunder.

11.5.    Entire Agreement; Amendment

     This Sale Agreement,  including the Disclosure  Schedule,  the Exhibits and
other Documents referred to herein or furnished pursuant hereto, constitutes the
entire  Agreement  among the  parties  hereto with  respect to the  transactions
contemplated  hereby,  and it supersedes  all prior oral or written  Agreements,
commitments or  understandings  with respect to the matters provided for herein.
No amendment, modification or discharge of this Sale Agreement shall be valid or
binding unless set forth in writing and duly executed and delivered by the party
against whom enforcement of the amendment, modification, or discharge is sought.

11.6.    Waiver

     No delay or  failure  on the part of any  party  hereto in  exercising  any
right, power or privilege under this Sale Agreement or under any other Documents
furnished in connection with or pursuant to this Sale Agreement shall impair any
such right, power or privilege or be construed as a waiver of any default or any
acquiescence  therein. No single or partial exercise of any such right, power or
privilege shall preclude the further exercise of such right, power or privilege,
or the exercise of any other right, power or privilege. 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.

11.7.    Severability

     If any part of any provision of this Sale Agreement or any other  Agreement
or document given pursuant to or in connection with this Sale 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 Sale
Agreement;  unless such invalid or  unenforceable  provision(s) are an essential
part of the agreed exchange.

                                      -35-

<PAGE>

11.8.    Governing Law

     This Sale Agreement  shall be governed by and construed in accordance  with
the laws of the  Commonwealth  of Virginia,  without regard to its principles of
conflicts of law that would give effect to the application of the law of another
jurisdiction.  Each of the parties hereto hereby irrevocably and unconditionally
consents  to  submit  to  the  exclusive  jurisdiction  of  the  courts  of  the
Commonwealth  of  Virginia  and of the United  States of  America,  in each case
having  jurisdiction over the County of Fairfax,  for any dispute arising out of
or  relating  to this  Sale  Agreement  and  the  Ancillary  Agreements  and the
transactions  contemplated  hereby and thereby  (and agrees not to commence  any
litigation  relating  thereto  except in such courts),  and further  agrees that
service of any process,  summons,  notice or document by U.S. registered mail to
its  respective  address  set forth in this Sale  Agreement  shall be  effective
service of process for any litigation brought against it in any such court. Each
of  the  parties  hereto  hereby  irrevocably  and  unconditionally  waives  any
objection  to the  laying of venue of any  litigation  arising  out of this Sale
Agreement  or  the  transactions  contemplated  hereby  in  the  courts  of  the
Commonwealth  of Virginia or the United  States of America,  in each case having
jurisdiction  over the County of Fairfax,  and hereby  further  irrevocably  and
unconditionally  waives  and agrees not to plead or claim in any such court that
any  such  litigation  brought  in  any  such  court  has  been  brought  in  an
inconvenient forum.

11.9.    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 Sale 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 telecopy  addressed as
follows:

                  (i)      If to Newco:

                           Motient Satellite Ventures LLC
                           10802 Parkridge Boulevard
                           Reston, Virginia 20191-5416
                           Attn:  Randy S. Segal, Esq.
                           Telecopy No.: 703-758-6134

                           with copies to:

                           Motient Satellite Ventures LLC
                           211 North Union Street, Suite 300
                           Alexandria, Virginia 22314
                           Attn:  Hal B. Perkins, Esq.
                           Telecopy No.: 703-706-3801

                           and

                                      -36-

<PAGE>

                           Dewey Ballantine LLP
                           1301 Avenue of the Americas
                           New York, NY  10019
                           Attn:  William J. Phillips, Esq.
                           Telecopy No.: 212-259-6333

                  (ii)     If to Motient Services:

                           Motient Services Inc.
                           10802 Parkridge Boulevard
                           Reston, Virginia 20191-5416
                           Attn:  Randy S. Segal, Esq.
                           Telecopy No.: 703-758-6134

                           and

                           Hogan & Hartson L.L.P
                           8300 Greensboro Drive
                           Suite 1100
                           McLean, VA  22102
                           Attn:  Richard K.A. Becker, Esq.
                           Telecopy No.: 703-610-6200

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  or  telecopied  in the  manner  described  above  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.

11.10.   Headings

     Section  headings  contained  in  this  Sale  Agreement  are  inserted  for
convenience  of  reference  only,  shall not be deemed to be a part of this Sale
Agreement  for any  purpose,  and  shall not in any way  define  or  affect  the
meaning, construction or scope of any of the provisions hereof.

11.11.   Interpretation; Absence of Presumption

     (a) For the purposes  hereof,  (i) words in the  singular  shall be held to
include  the  plural  and vice  versa and words of one  gender  shall be held to
include  the other  gender as the  context  requires,  (ii) the terms  "hereof",
"herein",  and "herewith" and words of similar  import shall,  unless  otherwise
stated,  be construed to refer to this Sale Agreement as a whole  (including all
of the  Exhibits  hereto)  and not to any  particular  provision  of  this  Sale
Agreement,  and  Article,  Section,  paragraph,  Exhibit  and  Schedule  to  the
Disclosure  Schedule  references  are to  the  Articles,  Sections,  paragraphs,
Exhibits and Schedule to the Disclosure  Schedule to this Sale Agreement  unless
otherwise specified, (iii) the word "including" and words of similar import when
used in this Sale Agreement shall mean "including,  without  limitation," unless
the context otherwise requires or unless otherwise specified, (iv) the word "or"
shall not be exclusive,  and (v) provisions shall apply,  when  appropriate,  to
successive events and transactions.

                                      -37-

<PAGE>

     (b)  This  Sale  Agreement  shall  be  construed   without  regard  to  any
presumption or rule requiring  construction or interpretation  against the party
drafting or causing any instrument to be drafted.

11.12.   Execution in Counterparts

     To  facilitate  execution,  this Sale  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 Sale  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.

11.13.   Limitation on Benefits

     The covenants, undertakings and agreements set forth in this Sale 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.

11.14.   Binding Effect

     Subject  to  any  provisions  hereof  restricting  assignment,   this  Sale
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.

-38-

<PAGE>

     IN  WITNESS  WHEREOF,  the  parties  hereto  have duly  executed  this Sale
Agreement,  or have  caused  this Sale  Agreement  to be duly  executed on their
behalf, as of the day and year first above written.

                                         MOTIENT SATELLITE VENTURES LLC

                                         By:  /s/Gary M. Parsons
                                              ------------------
                                         Name:  Gary M. Parsons
                                         Title: Chairman

                                         MOTIENT SERVICES INC.

                                         By:  /s/Gary M. Parsons
                                              ------------------
                                         Name:  Gary M. Parsons
                                         Title: Chairman

<PAGE>

Exhibit           Reference                                             Section

A                 Definitions                                            1
B                 Form of Bill of Sale and Limited Assignment
                      and Assumption Agreement                           8.1(e)

<PAGE>

                                    EXHIBIT A

                             TO ASSET SALE AGREEMENT

                            DATED AS OF JUNE 29, 2000

DEFINITIONS

     "Affiliate"  means:  (a) with  respect  to a  person,  any  member  of such
person's  family;  (b) with  respect to an entity,  any officer,  director,  ten
percent or more stockholder,  ten percent or more partner or ten percent or more
member of or in such entity or of or in any  Affiliate of such  entity;  and (c)
with  respect to a person or  entity,  any person or entity  which  directly  or
indirectly,  through one or more intermediaries,  Controls, is Controlled by, or
is under common Control with such person or entity.

     "Agreement"  means any concurrence of understanding  and intention  between
two or more persons (or entities) with respect to their  relative  rights and/or
obligations  or with  respect  to a thing  done  or to be done  (whether  or not
conditional, executory, express, implied, in writing or meeting the requirements
of contract),  including,  without  limitation,  contracts,  leases,  promissory
notes, covenants, easements, rights of way, covenants, commitments, arrangements
and memorandum understandings.

     "Ancillary  Agreements"  means the R&D  Agreement  and the  Cross-Licensing
Agreement of even date herewith.

     "Assets"  means  assets  of  every  kind and  everything  that is or may be
available  for  the  payment  of  liabilities  (whether  inchoate,  tangible  or
intangible), including, without limitation, real and personal property.

     "Claims"  means  all  demands,   claims,   actions  or  causes  of  action,
assessments,  losses, damages,  liabilities,  charges, complaints,  injunctions,
judgments,  orders,  decrees,  rulings, dues, fines, amounts paid in settlement,
obligations,  liens,  costs of  environmental  investigations  and/or  cleanups,
Taxes, costs and expenses,  including,  without limitation,  interest, penalties
and attorneys' fees and disbursements.

     "Code" means the Internal Revenue Code of 1986, as amended.

     "Control" means possession,  directly or indirectly,  of power to direct or
cause the  direction of  management or policies  (whether  through  ownership of
voting securities, by Agreement or otherwise).

     "Cross-Licensing  Agreement"  means  the  Cross-Licensing  and Bulk  Resale
Agreement of even date herewith  among  Motient  Communications,  Inc.,  Motient
Services and Newco.

     "Disclosure  Schedule"  means the  disclosure  schedule  identified  as the
Disclosure Schedule to this Sale Agreement.

     "Documents"  means  any  paper  or  other  material   (including,   without
limitation, computer storage media) on which is recorded (by letters, numbers or
otherwise)  information  that  may  be  evidentially  used,  including,  without
limitation, legal opinions, mortgages,  indentures, notes, instruments,  leases,
Agreements,   insurance  policies,   reports,   studies,   financial  statements
(including,  without  limitation,  the notes thereto),  other written  financial
information, schedules, certificates, charts, maps, plans, photographs, letters,
memoranda and all similar materials.

     "Encumbrance"  means 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.

     "Final FCC Order" means an order (or orders) of the FCC: (1)  consenting to
the assignment or transfer of control of the Licenses to Newco or one or more of
its  subsidiaries,  without the imposition of any conditions that may reasonably
be expected to result in a Newco Material  Adverse Effect,  and (2) with respect
to which:  (a) no request for a stay is pending,  no stay is in effect,  and any
deadline  that may be  designated  by statute or  regulation  for filing  such a
request  is  passed;  (b)  no  petition  for  rehearing  or  reconsideration  or
application  for  review  is  pending,  and the time that may be  designated  by
statute or regulation for filing any such petition or application is passed; (c)
there is no  reconsideration  by the FCC on its own motion and the time that may
be designated by statute or regulation for  initiating any such  reconsideration
has passed;  and (c) no appeal is pending or in effect,  and any  deadline  time
that may be designated  by statute or regulation  for filing any such appeal has
passed.

     "Financial  Statement"  shall have the  meaning  given such term in Section
4.18.

     "Hart-Scott-Rodino" means the Hart-Scott-Rodino  Antitrust Improvements Act
of 1976, as amended,  and all Laws promulgated pursuant thereto or in connection
therewith.

     "Intercompany Agreements" means all Agreements, liabilities and obligations
between  Motient  Services  and  Motient  Corporation  or any of its  direct  or
indirect  subsidiaries,  except  for  the  Ancillary  Agreements  or  any  other
Agreements delivered in connection herewith.

     "Investment  Agreement" means that certain  Investment  Agreement,  of even
date herewith,  by and among Motient Corporation,  Newco and the Investors named
therein.

     "Investor  Option"  means the  option to acquire  an  additional  number of
shares of Newco interests described in Section 2.1 of the Investment Agreement.

     "Laws"  means  all  foreign,  federal,  state  and  local  statutes,  laws,
ordinances,  regulations,  rules, resolutions,  orders,  determinations,  writs,
injunctions,  awards (including,  without limitation, awards of any arbitrator),
judgments and decrees applicable to the specified persons or entities and to the
businesses and assets thereof (including,  without limitation,  Laws relating to
securities  registration  and  regulation;   the  sale,  leasing,  ownership  or
management of real property;  employment  practices,  terms and conditions,  and
wages and hours;  building standards,  land use and zoning;  safety,  health and
fire prevention; but excluding Environmental Laws).

     "Liability" means any liability (whether known or unknown, whether asserted
or unasserted,  whether  absolute or contingent,  whether  accrued or unaccrued,
whether liquidated or unliquidated,  and whether due or to become due) including
any liability for Taxes.

     "Losses" means all demands,  losses,  Claims,  actions or causes of action,
assessments,  damages,  liabilities,  costs  and  expenses,  including,  without
limitation,   interest,   penalties   and   reasonable   attorneys'   fees   and
disbursements.

     "Material   Adverse  Effect"  means  a  material   adverse  effect  on  the
properties,  business, prospects,  operations,  earnings, assets, liabilities or
the condition (financial or otherwise) of Motient Services.

     "Motient Services Tax Returns" means all federal, state, local, foreign and
other applicable tax returns,  declarations of estimated tax reports required to
be filed by Motient Services.

     "Ordinary Course of Business" means ordinary course of business  consistent
with past practices.

     "Outside  Date" means the second  anniversary of the date hereof subject to
extension pursuant to Section 8.8 hereof.

     "Notice" shall have the meaning given such term in Section 3.1.

     "Purchase   Price"  means  (i)  One  Hundred  Forty  Four  Million  Dollars
($144,000,000)  if the Investment  Commitment Date (as defined in the Investment
Agreement) shall occur on or prior to the first  anniversary of the date hereof,
or (ii) One Hundred Forty Four Million Dollars  ($144,000,000) plus $118,356 per
day for each day  between  the  first  anniversary  of the date  hereof  and the
Investment  Commitment Date if the Investment  Commitment Date shall occur after
the first anniversary of the date hereof.  The Purchase Price shall be increased
by an amount  equal to any  increase  in the  Option  Price (as  defined  in the
Investment Agreement) pursuant to the last three sentences of Section 2.1 of the
Investment Agreement.

     "Real Property" means the real property owned, operated, or used by Motient
Services  as of  December  31,  1997,  any  additional  real  property so owned,
operated,  or used since that date,  and for  purposes of Section  4.4, any real
property formerly so owned, operated, or used.

     "R&D  Agreement"  means the Research &  Development,  Marketing and Service
Agreement between Newco and Motient Services.

     "R&D  Fee"  means the $20  million  fee paid by Newco to  Motient  Services
pursuant to the R&D Agreement.

     "Securities Act" means the Securities Act of 1933, as amended, and all laws
promulgated pursuant thereto or in connection therewith.

     "Shared Assets" shall have the meaning given such term in Section 8.5(a).

     "Taxes"  means all  federal,  state,  local and foreign  taxes  (including,
without  limitation,  income,  profit,  franchise,  sales,  use, real  property,
personal  property,  ad valorem,  excise,  employment,  social security and wage
withholding   taxes)  and   installments   of  estimated   taxes,   assessments,
deficiencies, levies, imposts, duties, withholdings, or other similar charges of
every kind,  character or description  imposed by any governmental  authorities,
and any interest, penalties or additions to tax imposed thereon or in connection
therewith.

     "Tax Liabilities" means any action, suit, proceeding,  audit, investigation
or Claim  pending  or  threatened  in  respect  of any Taxes  for which  Motient
Services is or may become liable,  or any deficiency or Claim for any such Taxes
that has been to Motient Services' knowledge proposed, asserted or threatened.

     "Tax Return" means any return,  declaration,  report,  claim for refund, or
information  return or statement  relating to Taxes,  including  any schedule or
attachment thereto, and including any amendment thereof.EXHIBIT 10.43

             RESEARCH & DEVELOPMENT, MARKETING AND SERVICE AGREEMENT

         THIS  RESEARCH &  DEVELOPMENT,  MARKETING  AND SERVICE  AGREEMENT  (the
"Agreement")  is  entered  into as of 29th day of  June,  2000  (the  "Effective
Date"),  by and between  Motient  Satellite  Ventures  LLC, a limited  liability
company organized under the laws of the State of Delaware, ("Newco") and Motient
Services  Inc.  ("Motient  Services"),  a  wholly-owned  subsidiary  of  Motient
Corporation ("Motient Corporation") both of which are corporations  incorporated
under the laws of the State of Delaware.

         WHEREAS  Motient  Services  owns or otherwise  controls  the  Satellite
Network (as defined below) and related FCC licenses and other  resources,  which
it uses collectively to provide mobile satellite communications services for its
existing customers; and

         WHEREAS Newco wishes to use the Satellite  Network to conduct  research
and development  activities to develop and test new applications and explore new
business opportunities for the Satellite Network; and

         WHEREAS,  Newco is willing  and  desirous  of  purchasing,  and Motient
Services wishes to provide,  access and use of the Satellite Network (as defined
below)  for  research,  development  and  testing  purposes  on  the  terms  and
conditions set forth in this Agreement.

         NOW THEREFORE in  consideration  of the mutual covenants and agreements
set forth below, the Parties hereby agree as follows.

                                    ARTICLE I

                            DEFINITIONS AND SCHEDULES

1.1 Definitions. In this Agreement, the following words and terms shall have the
respective meanings assigned to them as follows:

"Affiliate" shall mean any entity which,  directly or indirectly,  controls,  is
controlled by, or under common control with, a Party hereto.

"Asset Sale Agreement" means that certain Asset Sale Agreement between Newco and
Motient Services of even date herewith.

"Commercialization  Agreement"  shall have the meaning assigned to it in Section
2.4.

"Effective  Date"  is as  defined  immediately  prior  to  the  recitals  at the
beginning of this Agreement.

"Emergency Preemption" shall have the meaning assigned to it in Section 3.5.

"Existing  Business" shall mean,  collectively,  the Satellite Network,  the FCC
License,  and all of the Existing  Satellite Service  agreements between Motient
Services and any third party.

"Existing   Satellite   Services"  shall  mean,   collectively,   the  Satellite
Network-based communications services and applications that are within the scope
of  services  and  applications  provided,   directly  by  Motient  Services  or
indirectly  through  third party  resellers and other  intermediaries,  to third
parties as of the Effective Date, and any services or applications  that are (i)
reasonable  extensions  of the  services  and  applications  offered  by Motient
Services as of the Effective Date; and (ii) developed  independently  by Motient
Services  after the Effective  Date in the normal course of its business and not
arising out of the R&D Activities.

"FCC" shall mean the Federal Communications Commission.

"FCC  License"  means the  license  or  licenses  issued  by the FCC to  Motient
Services  authorizing use of the Satellite Network to provide Existing Satellite
Services within the Territory.

"Intellectual  Property  Rights"  mean any and all  franchise,  patents,  patent
qualifications,  copyrights, know-how, computer software, industrial designs and
drawings and general intangibles of like nature,  trade secrets,  licenses,  and
rights and filings with respect to the foregoing,  and all reissues,  extensions
and renewals thereof, but excluding  trademarks,  tradenames,  service marks and
service names.

"Investment  Agreement"  means  that  certain  Investment  Agreement  among  the
Investors, Newco and Motient Corporation dated June 22, 2000.

"Investors" shall have the meaning assigned to it in the Investment Agreement.

"Losses"  means all  demands,  losses,  claims,  actions  or  causes of  action,
assessments,  damages,  liabilities,  costs  and  expenses,  including,  without
limitation,   interest,   penalties   and   reasonable   attorneys'   fees   and
disbursements.

"Motient  Derivative Works" means any Technology that is developed or created by
or for Newco in connection with the R&D Activities, including without limitation
any  Technology  developed or created for Newco by Motient  Services  during the
course  of  providing  the R&D  Services  for  Newco,  but which  constitutes  a
modification or derivative work of any Motient Technology.

"Motient Services" means Motient Services Inc. and its successors and assigns.

"Motient Technology" means any Technology that is developed or created by or for
Motient Services and/or its Affiliates prior to the Effective Date, or after the
Effective Date but independently of the R&D Activities.

"Newco" means Motient Satellite Ventures LLC, and its successors and assigns.

"Newco  Takeover"  means  Newco's  acquisition  of  the  Existing  Business,  as
contemplated by the Asset Sale Agreement.

"Newco  Technology"  means any Technology  other than a Motient  Derivative Work
that is  developed  or  created  by or for  Newco  in  connection  with  the R&D
Activities, including without limitation any Technology developed or created for
Newco by Motient  Services  during the course of providing  the R&D Services for
Newco.

"New Satellite  Services" shall mean collectively,  the Satellite  Network-based
communications   services   (excluding  the  Existing  Satellite  Services)  and
constituting  new  applications  of the  Satellite  Network  developed  by Newco
pursuant  to the  R&D  Activities  including  without  limitation  fixed  mobile
satellite  services,  mobile  satellite  services,  and  voice,  video  and data
applications  that,  in each such case,  are  different  than  those  offered by
Motient Services as of the Effective Date,  excluding,  however, any services or
applications  that  are both  (i)  reasonable  extensions  of the  services  and
applications  offered by Motient  Services as of the  Effective  Date;  and (ii)
developed  independently  by Motient  Services  after the Effective  Date in the
normal course of its business and not arising out of the R&D Activities.

"Parent  Conversion" means the exchange or conversion of interests in Newco held
by one or more  Investors  into  shares of Motient  Corporation's  common  stock
pursuant to the provisions of the Investment Agreement.

"Party" means Newco or Motient Services.

"Power and Bandwidth  Agreement"  shall mean any agreement with a term in excess
of one (1) year  between  Motient  Services  and a third  party  that  obligates
Motient  Services  to commit to provide  both a  specified  amount of  satellite
transmission  power and a  specified  amount  of  bandwidth,  thereby  depleting
available Satellite Network power and bandwidth capacity.

"Proprietary Information" shall have the meaning assigned to it in Section 9.1.

"R&D Activities" shall have the meaning assigned to it in Section 2.1.

"R&D Services" means, collectively, the Services provided by Motient Services to
Newco to support Newco's R&D Activities, as specified in Section 4.1, and in the
R&D Support Plan to be developed pursuant to Section 4.1.

"Satellite Network" shall mean the satellite-based communications network owned,
leased or  otherwise  controlled  by, and  operated by,  Motient  Services,  and
consisting of the flight satellite,  certain earth stations,  gateways and other
ground  elements,  control  systems  including  telemetry,  tracking and control
systems and network operations centers,  and the related hardware,  software and
networking  resources  which are used  collectively  to  provide  the  Satellite
Services.  The Satellite  Network shall  automatically  include any additions or
modifications to the Satellite  Network made from time to time during the normal
course of Motient Service's business.

"Satellite  Services" shall mean collectively the New Satellite Services and the
Existing Satellite Services.

"Service Fee" shall have the meaning assigned to it in Article V.

"Service Payment Date" shall have the meaning assigned to it in Article V.

"Services"  includes  the R&D  Services  and the Support  Services  provided by
Motient Services to Newco pursuant to this Agreement.

"Support  Services"  shall mean the  services  provided by Motient  Services to
operate and maintain the Satellite  Network,  and any uplink  equipment or other
resources provided by Motient Services to Newco pursuant to this Agreement.

"Technology" means any software components including source code and object code
versions  thereof,  any  documentation,  reports,  analyses or other  printed or
recorded  materials,  whether  in  written,  electronic  or  other  format,  any
hardware,  any  graphics,  audio  or video  objects,  images,  photos,  artwork,
designs, concepts, inventions, methods, ideas, processes, and any other creative
works of authorship.

"Term" shall have the meaning assigned to it in Section 11.1.

"Territory"  is the area within  which  Motient  Services is licensed to use the
Satellite  Network to provide  Existing  Satellite  Services,  which,  as of the
Effective Date includes the United States, Puerto Rico, the U.S. Virgin Islands,
and U.S.  coastal  waters up to 200 miles on or over  ocean  areas  outside  the
territory of any foreign country.

1.2  Schedules.  The following  Schedules are annexed to this  Agreement and are
incorporated  into  this  Agreement  by  reference  and are to be a part of this
Agreement:

                  Schedule A        -       Facilities Requirements
                  Schedule B        -       Compensation for Services

                                   ARTICLE II

                         ACCESS RIGHTS AND RESTRICTIONS

2.1 Access and Use Rights.

Motient  Services hereby grants to Newco,  for the Term of this  Agreement,  the
non-transferable (except in accordance with Article XIV) right to access and use
the Satellite  Network solely for purposes of conducting  technical,  regulatory
and  commercial  research and  development  of New Satellite  Services (the "R&D
Activities").  During the Term of this  Agreement  and  subject to the terms set
forth herein,  Motient  Services agrees that Newco's right to access and use the
Satellite  Network for conducting  the R&D  Activities  will be exclusive in the
respect that Motient  Services will not provide,  or offer to provide,  Services
(or services that are substantially  similar to the Services) to any third party
for the  purpose  of  assisting  such third  party in  conducting  research  and
development of New Satellite  Services.  Motient  Services  further agrees that,
during the Term of this Agreement,  it shall not grant,  or offer to grant,  the
right to promote,  market,  commercialize or offer New Satellite Services to any
other party.

2.2 Allocation of Capacity.

Motient  Services  agrees to provide Newco with up to 1.25 MHz of bandwidth,  in
such channel  configuration  or  configurations  as the parties  shall  mutually
agree,  to enable  Newco to  conduct  the R&D  Activities  contemplated  by this
Agreement.  Unless  otherwise  agreed by the  parties,  Motient  Services  shall
provide a minimum of 6 kHz of bandwidth to Newco.  The  bandwidth to be provided
by Motient  Services shall be in at least one of Motient  Services'  Continental
United States ("CONUS") satellite beams. Subject to the terms of this Agreement,
Motient  Services shall also consider the feasibility of providing  bandwidth in
additional  (or  substitute)  CONUS beams.  Motient  Services  shall provide the
foregoing  bandwidth  to Newco at power  levels  to be  mutually  agreed  by the
parties, in light of Newco's R&D Activities and subject to the  non-interference
provisions and other terms of this Agreement.

Newco  agrees to use its  commercially  reasonable  efforts  to  advise  Motient
Services in writing at least sixty (60) days in advance of the beams in which it
may request  channels.  Newco agrees that Motient Services reserves the right to
plan the use of the satellite  capacity by balancing the  deployment of channels
and of capacity  purchased by Motient Services' other customers.  Once a channel
is activated pursuant to the foregoing provisions,  it shall remain active until
Newco  informs  Motient  Services  that  its use of such  channel  is no  longer
required.  Motient Services' obligations under this Section 2.2 shall be subject
to the limitations of Section 2.3.

2.3 Excess Capacity.

Newco's  right to access and use the  Satellite  Network shall be subject at all
times  to  Motient  Services'  right to use the  Satellite  Network  to  provide
Existing Satellite Services. Newco's right of access and use shall be limited to
use of excess  Satellite  Network  capacity not required by Motient  Services to
provide the Existing Satellite Services.  Newco acknowledges and agrees that the
Satellite Network capacity required to provide the Existing  Satellite  Services
may increase during the Term of this Agreement,  thereby resulting in a decrease
of the excess capacity  available to Newco to conduct its R&D Activities.  Newco
agrees that Motient Services shall have no liability to Newco as a result of any
such decrease in excess capacity.  Motient  Services  reserves the right, in its
sole  discretion,  to deal with all matters  relating to the Satellite  Network,
including without  limitation the operation and allocation of satellite capacity
among  all of its  services  and  customers,  except as  otherwise  agreed to in
Section 2.1.

During the Term,  Motient  Services  shall provide Newco with  reasonable  prior
written notice of any new Power and Bandwidth  Agreements that Motient  Services
proposes  to enter into with any third  party  ("Proposed  Contract").  If Newco
reasonably  determines  that the Proposed  Contract  materially  interferes with
Newco's rights under this Agreement, Newco shall have fifteen (15) days from the
receipt  of such  notice to notify  Motient  Services  of its  objection  to the
Proposed Contract. If Newco fails to provide Motient Services with notice of its
objection  within said  fifteen  (15) day period,  Newco shall be deemed to have
agreed that Motient Services may enter into the Proposed Contract.  In the event
of an objection by Newco as provided  above within said fifteen (15) day period,
Motient Services shall not enter into the Proposed Contract.

2.4 Access Restrictions.

Except to the extent provided for in any Commercialization  Agreement, Newco may
not use the  Satellite  Network for any purpose  other than  conducting  the R&D
Activities.   Without  limiting  the  preceding  sentence,  Newco  is  expressly
prohibited from using the Satellite Network to provide  communications  services
for use in its  ongoing  business  activities  or for the  benefit  of any third
party. Newco may authorize third parties to access and use the Satellite Network
for purposes of assisting Newco to conduct the permitted R&D Activities,  but is
otherwise prohibited from permitting any third party to gain access to or use of
the  Satellite  Network  for any  other  reason,  except  as  authorized  by the
Commercialization  Agreement  (as  defined  below).  During  the  Term  of  this
Agreement,  Newco may promote,  market, and demonstrate any of the New Satellite
Services to third  parties,  but may not  provide,  enter into any  agreement to
provide, or otherwise commercialize,  the New Satellite Services until Newco and
Motient Services have first entered into a separate  network services  agreement
authorizing such activities (the "Commercialization Agreement"). Upon request by
Newco,  Motient Services and Newco will negotiate in good faith the terms of the
Commercialization  Agreement,  provided  that Motient  Services  agrees to offer
Newco terms for the  Commercialization  Agreement that are consistent with those
terms  Motient  Services  offers  generally  to  its  other  Satellite   Service
resellers, and Motient Services further agrees to provide such services at rates
no  less  favorable  than  those  provided  to any of  Motient  Services'  other
similarly  situated Satellite Service resellers that have purchased or committed
to purchase a like volume of Satellite Network power and bandwidth capacity from
Motient  Services.  Newco is prohibited from using the Satellite  Network in any
manner that will or is likely to disrupt or interfere with the Satellite Network
or Motient Service's ability to provide the Existing Satellite Services or both.
Newco further  agrees to comply with the facilities  requirements  applicable to
the Satellite Network, as described in Schedule A.

2.5 Continuing Rights of Motient Services.

Motient  Services shall retain all rights with respect to the Satellite  Network
not  expressly  granted  to  Newco  under  this  Agreement,  including,  without
limitation,  the rights:  (i) to use the Satellite  Network to provide  Existing
Satellite  Services for itself and for third parties in the normal course of its
business;  and (ii) to enter into new  agreements for the provision or resale of
Existing  Satellite  Services  to third  parties on any  basis.  Nothing in this
Agreement shall require Motient Services' to violate its obligations as a common
carrier  licensed  by the FCC with  respect to the  selling of capacity to third
party resellers.

                                   ARTICLE III

                           SATELLITE NETWORK SERVICES

3.1 Provision of Satellite Network Facilities.

Motient  Services  shall operate and maintain the Satellite  Network  during the
Term of this  Agreement  to the extent  required to provide  Existing  Satellite
Services.  Motient Services shall be responsible to provide, at its expense, all
hardware,  software, equipment and other resources necessary to provide, operate
and maintain the Satellite  Network to the extent required for Motient  Services
to provide the Existing Satellite Services.  Motient Services reserves the right
to determine, in its discretion, the particular hardware, software, equipment or
other  resources  to be used to provide,  operate  and  maintain  the  Satellite
Network, the location of any facilities, operations centers, and other resources
used in  connection  with the  Satellite  Network,  the  personnel to be used to
provide Support Services,  and any third party vendors,  service  providers,  or
other suppliers used to source any of the foregoing items.

3.2 Provision of R&D Equipment and Resources.

Newco shall be responsible to provide,  operate and maintain at its expense, any
hardware,  software,  equipment  and other  resources  additional  to that to be
provided  by Motient  Services  pursuant  to Section  3.1,  as and to the extent
required for Newco to conduct its R&D Activities and to develop and test any New
Satellite Services.  Motient Services shall have the right to review and approve
in advance any such additional hardware,  software, equipment or other resources
proposed by Newco to be integrated  with, or otherwise used in connection  with,
the  Satellite  Network  to ensure  that it will not unduly  interfere  with the
Satellite  Network  and/or the provision of Existing  Satellite  Services,  such
approval not to be unreasonably withheld.

3.3 Provision of Uplink Equipment.

Motient  Services  shall,  at its expense,  make  available to Newco  reasonable
access to Motient Services' existing  ground-based  uplink equipment required to
access and use the Satellite Network,  consistent with that used by, or provided
to,  power and  bandwidth  users of the  Existing  Satellite  Services.  Motient
Services  shall  designate  a  facility  for use by  Newco  to  conduct  the R&D
Activities. Motient Services will use commercially reasonable efforts to support
and maintain  such uplink  equipment  consistent  with Section 3.4 below.  Newco
shall,  at its  expense,  be  responsible  to provide,  operate and maintain any
additional uplink equipment required by Newco to conduct the R&D Activities.

3.4 Maintenance of Satellite Network.

Motient  Services  shall use  commercially  reasonable  efforts to maintain  the
Satellite Network and any uplink equipment  provided by Motient Services in good
working condition.  Motient Services shall provide Newco with a telephone number
to be used to obtain  support for the Satellite  Network and to report  problems
and defects in the  Satellite  Network or uplink  equipment  provided by Motient
Services.  Motient Services will use commercially  reasonable efforts to correct
problems and defects in the Satellite Network or such uplink equipment  reported
by Newco  within a  reasonable  time.  Motient  Services  reserves  the right to
interrupt  Newco's access and use of the Satellite  Network in order for Motient
Services to perform  scheduled  maintenance  of the Satellite  Network.  Motient
Services shall provide Newco with reasonable  advance written notice of any such
scheduled maintenance.

3.5 Emergency Preemption or Suspension of Service.

Newco's use of the Satellite Network may be preempted,  interrupted or suspended
due to  conditions  or  reasons  beyond  Motient  Services'  reasonable  control
("Emergency  Preemption"),   including  but  not  limited  to:  (i)  maintenance
requirements or emergency conditions  experienced by Motient Services;  (ii) the
protection of Motient Services' personnel,  facilities or services; or (iii) the
provision of priority and preemptive  access to Motient  Services'  satellite as
required by the U.S. Coast Guard, the Federal Aviation  Administration  or other
governmental  agency to provide responsive  emergency support during any natural
or man-made disasters.

3.6 Notice to Newco of Suspension or Emergency Preemption of Service.

In the event of any Emergency Preemption, Motient Services shall notify Newco as
soon as practicable and shall use  commercially  reasonable  efforts to make the
Satellite  Network  available to Newco to conduct R&D  Activities  as quickly as
practicable.

                                   ARTICLE IV

                              R&D SUPPORT SERVICES

4.1 R&D Support Plan.

Motient  Services  agrees to  provide  Newco  with the  system  interfacing  and
engineering  support necessary for Newco to interface with the Satellite Network
as  required  for Newco to perform  its R&D  Activities  under  this  Agreement,
subject to the terms and conditions of this Agreement.  Within a reasonable time
after the Effective Date,  Motient Services and Newco shall develop and mutually
agree upon the details of an R&D support services plan (the "R&D Support Plan"),
identifying the consulting, engineering, technical and other personnel and other
resources  to be  provided  by  Motient  Services  in  support  of  Newco's  R&D
Activities, as well as identifying any third party consultants, engineers and/or
other  third  party  resources  that Newco  will  engage to assist it in its R&D
Activities.  Motient  Services  will provide Newco with  additional  support for
Newco's R&D  Activities as and when  requested by Newco,  to the extent  Motient
Services has the  personnel  required to provide such  support,  and,  except as
provided in Schedule B, such support shall be provided without additional charge
to  Newco.  The  parties  agree  that any third  party  consultants  or  service
providers  engaged by Newco to assist Newco in R&D  Activities  shall execute an
appropriate   non-disclosure  or  confidentiality   agreement  to  preserve  the
confidentiality of Newco's R&D Activities. The R&D Support Plan shall specify in
detail the quantity and type of personnel  resources  and other  resources to be
provided by Motient  Services in order for Newco to conduct its R&D  Activities,
and the  schedule  specifying  when such  resources  will be  required.  Motient
Services shall make the resources specified in the R&D Support Plan available to
Newco in accordance  with such  schedule.  The R&D Support Plan shall be updated
periodically  during  the Term of this  Agreement,  as  reasonably  required  to
support  Newco's  R&D  Activities.  Newco  shall  have  complete  discretion  to
determine  the  scope  and  level of R&D  Activities  in which it may  choose to
engage, to the extent not inconsistent with this Agreement.

4.2 Testing Process.

Motient  Services  agrees  to  make  reasonable  configuration  changes  to  the
Satellite  Network as required to support  Newco's R&D  Activities in accordance
with the following process, provided such changes are conducted in a manner that
will not adversely affect the Existing Satellite Services.  Prior to undertaking
any R&D Activities that will require any such configuration change, or that will
or may adversely affect the Satellite  Network and/or Motient  Service's ability
to provide  Existing  Satellite  Services,  Newco shall provide Motient Services
with  a  test  plan  set  forth  in  writing   which   describes  the  requested
configuration  change,  the testing to be undertaken,  the proposed schedule for
such testing,  the risks to the Satellite Network and/or the Existing  Satellite
Services imposed by such testing, the steps to be taken to eliminate or mitigate
the risks,  and any other  pertinent  information  regarding  the  proposed  R&D
Activities  (each  a "Test  Plan").  Motient  Services  will  have a  reasonable
opportunity to review the Test Plan prior to  commencement  of testing.  Motient
Services may require changes in the Test Plan before approving the Test Plan, if
Motient Services  reasonably believes that such changes are required to minimize
risk to the Satellite  Network and/or its ability to provide Existing  Satellite
Services.  Notwithstanding the foregoing, Motient Services reserves the right to
disapprove  any proposed  Test Plan and to prohibit any proposed  testing in the
event Motient  Services  reasonably  believes that such testing poses a material
risk to the Satellite Network,  and/or its ability to provide Existing Satellite
Services.

4.3 Project Management.

Each Party shall  appoint a project  manager  ("Project  Manager")  who shall be
responsible to oversee such Party's activities and  responsibilities  under this
Agreement  and to  communicate  with the  Project  Manager of the other Party to
coordinate  their  respective  activities  hereunder,  and to resolve issues and
disputes that arise during the Term of this Agreement. Each Party may change its
Project Manager upon prior written notice to the other Party.

4.4 Dispute Resolution.

The parties shall attempt to resolve any disputes  arising out of or relating to
this Agreement by negotiations  between the party's respective Project Managers.
In the event that the Project  Managers  are unable to resolve any such  dispute
within  a  reasonable   time,  such  dispute  shall  be  escalated  in  turn  to
successively higher level managers of each party who will attempt to resolve the
dispute  through  negotiation.  If, despite such attempts,  such dispute remains
unresolved  after a period  of sixty  (60) days  from the date  first  raised by
either  Project  Manager,  then such  dispute  shall be  submitted  to final and
binding arbitration before JAMS/ENDISPUTE  ("JAMS"), or its successor,  pursuant
to the United States  Arbitration Act, 9 U.S.C.  Sec. 1 et seq. Either party may
commence  the  arbitration  process  called  for in this  agreement  by filing a
written demand for arbitration  with JAMS,  with a copy to the other party.  The
arbitration  will  be  conducted  in  accordance  with  the  provisions  of JAMS
Streamlined  Arbitration Rules and Procedures in effect at the time of filing of
the demand for arbitration.  Any such arbitration shall take place at a mutually
agreed location within the Washington,  D.C. metropolitan area. The parties will
cooperate  with JAMS and with one another in selecting an  arbitrator  from JAMS
panel of neutrals,  and in scheduling the arbitration  proceedings.  The parties
covenant that they shall  participate in the arbitration in good faith, and that
they shall share equally in its costs. The provisions of this Section 4.4 may be
enforced  by any  Court  of  competent  jurisdiction.  The  costs  of  any  such
arbitration  shall be shared  equally by the parties;  provided  that each party
shall bear the costs of preparing and presenting  its own case. The  arbitrators
shall have no power to award any punitive damages.  The arbitrator's award shall
be  final  and  binding,   and  may  be  enforced  in  any  court  of  competent
jurisdiction.  The  results  of any  such  arbitration  shall  be  deemed  to be
Proprietary Information under this Agreement.

                                    ARTICLE V

                                     PAYMENT

On or before  July 14,  2000,  Newco  shall pay to  Motient  Services a one-time
service fee in the amount of Twenty Million Dollars  ($20,000,000) (the "Service
Fee") (the date upon which such  payment is made shall be the  "Service  Payment
Date").  Such payment  shall be made by wire transfer of  immediately  available
funds to an account designated in writing by Motient Services.  Motient Services
shall  have no  obligation  to  provide  any  Satellite  Services  or any  other
Services,  or to otherwise  fulfill any of its obligations  under this Agreement
prior to the Service  Payment Date. The Service Fee  represents  full payment in
advance for all support and other services to be provided by Motient Services to
Newco pursuant to this Agreement, except for those services requiring additional
payment,  as specified in Schedule B. Motient  Services  shall be responsible to
pay any sales and use taxes or  similar  such taxes  levied or imposed  upon the
Services provided by Motient Services to Newco pursuant to this Agreement.

                                   ARTICLE VI

                              REGULATORY COMPLIANCE

6.1 Responsibilities of Motient Services.

In  performing  the Services and  fulfilling  its other  obligations  under this
Agreement,  Motient Services shall comply with all applicable laws, regulations,
rules,  ordinances  and other legal and  administrative  obligations  applicable
thereto,  including without  limitation the terms of any applicable FCC License.
Motient  Services shall be responsible to secure and maintain in effect,  at its
expense,  and shall  use all  commercially  reasonable  efforts  to  secure  and
maintain  all  licenses,  permits,  rights-of-way,   approvals,  and  any  other
arrangements  necessary for providing,  operating and  maintaining the Satellite
Network  and  for  providing  Existing  Satellite  Services,  including  without
limitation  all  required  FCC  or  other  governmental  licenses,   permits  or
approvals.

6.2 Responsibilities of Newco.

In conducting the R&D Activities and fulfilling its other obligations under this
Agreement,  Newco shall comply with all  applicable  laws,  regulations,  rules,
ordinances and other legal and administrative  obligations  applicable  thereto,
including  without  limitation the terms of any  applicable  FCC License.  Newco
shall be  responsible  to secure and  maintain in effect,  at its  expense,  all
licenses,  permits,   rights-of-way,   approvals,  and  any  other  arrangements
necessary  for  carrying  out the R&D  Activities  and for using  the  Satellite
Network to research, develop and test New Satellite Services,  including without
limitation  all  required  FCC  or  other  governmental  licenses,   permits  or
approvals,  but excluding  those items which Motient  Services is responsible to
obtain as  specified in Section  6.1.  Newco shall confer with Motient  Services
prior to obtaining any additional licenses, permits, rights-of-way, approvals or
other  arrangements  for which it is responsible,  to allow Motient  Services to
coordinate  such  activities with its own regulatory  compliance  program.  Upon
request  by  Newco,   Motient  Services  shall  provide  Newco  with  reasonable
cooperation and support to assist Newco in obtaining any such licenses, permits,
rights-of-way,  approvals  or other  arrangements,  and, if  requested by Newco,
Motient Services shall obtain any such license, permit,  right-of-way,  approval
or other  arrangement in its own name;  provided that Newco shall be responsible
to  reimburse  Motient  Services for any costs  incurred by it to obtain  and/or
maintain any FCC licenses,  permits,  and approvals that would  otherwise be the
responsibility  of Newco under this Section 6.2.  Newco shall use the  Satellite
Network only for lawful  purposes and in compliance  with all applicable  rules,
policies and  regulations  of Motient  Services,  the FCC and those of any other
federal, state, or local governmental agencies.

6.3 Relationship to FCC.

The Satellite  Network and any Services  provided by Motient Services under this
Agreement,  are  subject to the  continuing  approval of the FCC.  Newco  hereby
consents to the filing of this  Agreement with the FCC if required by applicable
law and  regulation.  Motient  Services  shall advise Newco in advance of such a
filing.  The Parties will  cooperate to seek such  approvals  and  coordination,
provided that Motient  Services will be solely  responsible  for all FCC matters
relating to the Satellite Network and the Existing Satellite Services, including
but not limited to frequency coordination.

6.4 Notification Regarding FCC Actions.

Each party  shall use  commercially  reasonable  efforts to keep the other party
apprised of its licensing and regulatory activities with respect to the FCC, the
status of any  filings  made by such party with the FCC,  and of any  actions or
rulings  of the FCC of which  such  party is aware,  to the  extent  such  party
reasonably   determines  that  any  of  the  foregoing  materially  affects  the
activities  of the other party with  respect to this  Agreement,  the  Satellite
Network,  or the  R&D  Activities  and  other  activities  contemplated  by this
Agreement.

                                   ARTICLE VII

                      ADDITIONAL OBLIGATIONS OF THE PARTIES

7.1 Ethical Responsibilities of the Parties.

Motient  Services and Newco shall each refrain  from doing  anything  that would
tend to reflect  adversely  upon, or in any manner injure the  reputation of the
other (or their  respective  parent entities and affiliates) or adversely affect
the  other,  or,  in the case of  Motient  Services,  adversely  affect  Motient
Services' status as a licensed common carrier, except that a Party's enforcement
of its rights and  performance of its duties and  obligations  contained  herein
shall not be deemed a violation of this Section 7.1.

7.2 Insurance.

Until the Newco Takeover occurs,  Motient Services is responsible to ensure that
it is covered at all times by  insurance  consistent  with levels of coverage in
effect as of the Effective Date.

                                  ARTICLE VIII

                              INTELLECTUAL PROPERTY

8.1 Newco Technology.

Newco  shall  retain all right,  title and  interest  in and to any of the Newco
Technology  developed or created  during the course of this  Agreement by or for
Newco, including all Intellectual Property Rights therein. To the extent Motient
Services acquires any interest in the Newco Technology,  Motient Services hereby
assigns,  transfers and conveys to Newco all of its right, title and interest in
and to the Newco Technology, including all Intellectual Property Rights therein.

8.2 Motient Technology.

Motient  Services  shall  retain all  right,  title and  interest  in and to any
Motient  Technology  used by or  licensed  to Newco  during  the  course of this
Agreement,  including all  Intellectual  Property Rights therein.  To the extent
Newco  acquires any interest in the Motient  Technology,  Newco hereby  assigns,
transfers and conveys to Motient  Services all of its right,  title and interest
in and to the Motient  Technology,  including all  Intellectual  Property Rights
therein.

8.3 Motient Derivative Works.

Newco  shall  retain  all  right,  title  and  interest  in and  to any  Motient
Derivative  Works developed or created during the course of this Agreement by or
for Newco,  including  all  Intellectual  Property  Rights  therein,  subject to
Motient Service's continued ownership of any Motient Technology contained in any
such  Motient  Derivative  Work.  To the extent  Motient  Services  acquires any
interest in any Motient  Derivative  Works,  Motient  Services  hereby  assigns,
transfers  and conveys to Newco all of its right,  title and  interest in and to
the  Motient  Derivative  Works,  including  all  Intellectual  Property  Rights
therein,  but excluding any underlying Motient Technology  contained in any such
Motient Derivative Works.

8.4 License to Newco.

Motient  Services  hereby  grants  to  Newco a  non-exclusive,  non-transferable
(except in the event of an  assignment  of this  Agreement  in whole by Newco as
authorized in Article XIV), royalty-free license to use, reproduce,  modify, and
to distribute  internally,  but not to sublicense to third parties,  any Motient
Technology  that is needed  for Newco to  perform  the R&D  Activities.  Newco's
licensed rights to the Motient  Technology are restricted solely for the purpose
of conducting the R&D  Activities,  and for system  development,  deployment and
operations  activities  in the conduct of its own business and customer  service
pursuant to any Commercialization  Agreement.  Notwithstanding the foregoing, to
the extent  provided in any  Commercialization  Agreement,  Newco may sublicense
rights to use such Motient Technology to third parties to the extent required by
them to use any New  Satellite  Services  that  may be  provided  by  Newco.  In
addition,  in the event that the Asset Sale  Agreement is  terminated  due to an
event arising under  Section 8.8, 8.9 or 8.10 of the Asset Sale  Agreement,  the
license  granted  above in this  Section 8.4 shall be  modified as follows:  (i)
Newco's  licensed  rights  shall  be  limited  to that  portion  of the  Motient
Technology   that  is  actually   contained   in  a  Motient   Derivative   Work
("Incorporated  Motient  Technology);  (ii) Newco may thereafter use, reproduce,
and  modify  such  Incorporated  Motient  Technology,  and  may  distribute  and
sublicense such Incorporated  Motient Technology for any lawful purpose, so long
as such Incorporated Motient Technology at all times remains a part of a Motient
Derivative  Work;  (iii) Newco may  exercise  such  licensed  rights as modified
without  the  need  to  enter  into  any  Commercialization  Agreement;  (iv) as
modified,   such  licensed  rights  shall  be  perpetual,   notwithstanding  any
termination of this  Agreement;  and (v) as modified,  such license shall remain
transferable  in connection with an assignment of this Agreement as specified in
the first sentence of this Section 8.4.

8.5 Further Assurances.

Each  Party  will upon  request  of the other  Party,  and at the other  Party's
expense,  assist the other Party as reasonably  necessary with  applications for
trademarks,   patents,  copyrights  or  other  forms  of  intellectual  property
protection  with  respect to the  Technology  owned by or licensed to such other
Party  pursuant  to this  Agreement.  Each  Party  will  execute  any  documents
reasonably  requested  by the other  Party for the purpose of  establishing  its
right of  ownership  to such  Technology  without  the  need for any  additional
compensation.

                                   ARTICLE IX

                                 CONFIDENTIALITY

9.1 General.

Each Party  acknowledges  that during the course of this  Agreement  it may gain
access to confidential  information belonging to or relating to the other Party,
including  but  not  limited  to  any  business,   financial  and  technological
information   (collectively,   "Proprietary   Information")   which  Proprietary
Information  constitutes  valuable  assets and trade secrets of the other Party.
"Proprietary  Information" of Newco shall include information  regarding the R&D
Activities  to be  conducted  by Newco  under this  Agreement,  and the  results
thereof.  Accordingly, when a Party (the "Receiving Party") receives Proprietary
Information  from the other Party (the  "Disclosing  Party") the Receiving Party
shall,  both  during  the Term of this  Agreement  and for a period of three (3)
years following expiration or termination thereof:

     (a) keep secret and retain in strict confidence any Proprietary Information
received from the Disclosing Party;

     (b)  not   disclose  to  any  third  party  any   Proprietary   Information
received/from   the  Disclosing  Party  for  any  reason  whatsoever  except  as
authorized under this Agreement;

     (c) not disclose any Proprietary  Information  received from the Disclosing
Party to the  Receiving  Party's  and its  Affiliates'  employees,  except  on a
need-to-know basis; and

     (d)  not  make  use  of  any  Proprietary  Information  received  from  the
Disclosing  Party for its own  purposes  or for the  benefit of any third  party
except as authorized by this Agreement.

9.2 Requested or Required Disclosure.

Notwithstanding  Section 9.1, if the Receiving Party is requested or required to
disclose  Proprietary  Information of the Disclosing  Party pursuant to: (i) any
federal or state law or regulation;  or (ii) the order or request of any federal
or state court, or regulatory  entity or agency,  the Receiving Party shall: (A)
in  the  event  of a  request  for  such  Proprietary  Information  by a  court,
regulatory entity or agency,  use commercially  reasonable efforts to obtain the
written consent of the court or agency to maintain the  confidentiality  of such
Proprietary Information; (B) provide written notice to the Disclosing Party; and
(C) furnish only such portion of the  Proprietary  Information  as the Receiving
Party is legally required to disclose.

9.3 Disclosure to Third Parties.

Each  party  covenants  not to  divulge  Proprietary  Information  to any  third
parties,  except as set forth in Section 9.2, without  obtaining a nondisclosure
agreement  from such  party,  wherein  such  third  party  undertakes  to handle
Proprietary  Information  under  confidentiality  terms and  conditions  no less
restrictive than those set forth in this Agreement.

9.4 Exceptions.

The  obligations of this Article IX shall not extend to any  information  which:
(a) is in the public  domain;  (b) comes into the public domain through no fault
of the  parties or their  employees;  (c) is  already  lawfully  known,  free of
restrictions, to the Receiving Party at the time of its receipt; (d) is received
by the  Receiving  Party from a third  party who is not under an  obligation  of
confidence  with  respect  to  such  information;  (e)  is  known  or  developed
independently  of the disclosure by the Disclosing Party as can be proved by the
Receiving Party's  contemporaneous  business  records;  or (f) is required to be
disclosed by a government or regulatory agency, by court order or by law.

9.5 Events upon Termination.

Upon  any  expiration  or  termination  of this  Agreement,  or upon  demand  by
Disclosing  Party,  Receiving Party shall promptly return any documents or other
materials  containing  Proprietary   Information  of  Disclosing  Party  in  its
possession,  or shall certify to Disclosing  Party that such  documents or other
materials containing  Proprietary  Information have been destroyed,  except that
the Receiving  Party need not return or destroy any documents or other materials
containing Proprietary  Information consisting of Technology that is licensed to
the Receiving Party under a license which survives expiration or termination.

9.6 Injunction.

Both  parties  acknowledge  that  remedies  at law for breach of either  party's
obligations  under this  Article IX may be  inadequate,  that the  non-breaching
party may be irreparably harmed by any such breach, and that in the event of any
such  breach,  the  non-breaching  party shall be  entitled  to obtain  specific
performance or injunctive relief without a requirement to post bond.

                                    ARTICLE X

                         REPRESENTATIONS AND WARRANTIES

10.1 Representations and Warranties.

     (a) Motient Services represents and warrants to Newco as follows:

          (i) it has the  authority  to enter into and perform  this  Agreement;
     this Agreement when executed, will be legal, valid and binding upon it, and
     will be  enforceable  in  accordance  with  its  terms;  and it has made no
     misrepresentations  to the other party in connection with the  negotiation,
     execution, or performance of this Agreement; and

          (ii) the execution and performance of this Agreement does not and will
     not  violate  (x) the Series A and Series B 12 1/4%  Senior  Notes due 2008
     Indenture,  dated March 31, 1998, of Motient Holdings Inc.  ("Holdings") or
     (y) any other contract, obligation, or instrument held by it or to which it
     is a party,  or which is  binding  upon it,  including  terms  relating  to
     covenants not to compete and confidentiality obligations; and

          (iii) provided that Newco complies with its obligations  under Section
     6.2, the execution and  performance of this  Agreement by Motient  Services
     does not and will not  violate any  applicable  laws,  regulations,  rules,
     ordinances  and  other  legal  and  administrative  obligations  applicable
     hereto; and

          (iv) it  possesses  all  licenses  issued  by the FCC,  and all  other
     licenses,  permits,  franchisers  and  similar  authorizations,   that  are
     required for the  operation of the  Satellite  Network and for provision of
     Existing Satellite  Services as presently  conducted on the Effective Date,
     and the  ownership,  operation,  lease and  holding by it of the  Satellite
     Network  resources  (the  "Company   Permits").   Motient  Services  is  in
     compliance with the terms of the Company Permits.

     (b) Newco represents and warrants to Motient Services as follows:

          (i) it has the  authority  to enter into and perform  this  Agreement;
     this Agreement when executed, will be legal, valid and binding upon it, and
     will be  enforceable  in  accordance  with  its  terms;  and it has made no
     misrepresentations  to the other party in connection with the  negotiation,
     execution, or performance of this Agreement; and

          (ii) the execution and performance of this Agreement does not and will
     not violate any other contract,  obligation, or instrument held by it or to
     which it is a party, or which is binding upon it,  including terms relating
     to covenants not to compete and confidentiality obligations.

10.2 Disclaimer of Warranty.

EXCEPT AS  OTHERWISE  PROVIDED  IN THIS  AGREEMENT,  MOTIENT  SERVICES  MAKES NO
WARRANTY OR CONDITION,  EXPRESS OR IMPLIED,  REGARDING THE SATELLITE  NETWORK OR
ANY OTHER ITEM OF EQUIPMENT,  HARDWARE,  SOFTWARE OR ANY OTHER RESOURCE PROVIDED
BY MOTIENT SERVICES PURSUANT TO THIS AGREEMENT,  OR THE PROVISION OF ANY SERVICE
PROVIDED BY MOTIENT  SERVICES  PURSUANT  TO THIS  AGREEMENT,  INCLUDING  BUT NOT
LIMITED  TO  THE  IMPLIED  WARRANTIES  OF  MERCHANTABILITY  AND  FITNESS  FOR  A
PARTICULAR PURPOSE.

                                   ARTICLE xi

                              TERM AND TERMINATION

11.1 Term.

This  Agreement  shall commence on the Effective Date and shall remain in effect
for a period of three (3) years after the Effective  Date (the  "Term"),  unless
sooner  terminated in accordance  with Sections 11.3, or 11.4 hereof,  whichever
occurs first.

11.2 Suspension by Motient Services.

Motient Services may immediately suspend Newco's access to the Satellite Network
and the  provision  of any  Service to Newco  without any  liability  of Motient
Services  to Newco or to any  third  party  upon  the  occurrence  of any of the
following:

          (i) Newco's use of the  Satellite  Network or  performance  of the R&D
     Activities  is in violation of any statute or law or of any order,  rule or
     regulation of any court, agency or government authority; or

          (ii) Newco's use of the Satellite  Network or  performance  of the R&D
     Activities  is conducted in a manner that  materially  interferes  with the
     Satellite  Network and/or Motient Services' ability to provide the Existing
     Satellite Services.

Upon the occurrence of any such event,  Motient  Services shall use commercially
reasonable  efforts to provide  prior  written  notice to Newco and a reasonable
opportunity to cure prior to imposing any such suspension,  but Motient Services
reserves the right to suspend  access to the Satellite  Network and provision of
Services  to  Newco  immediately   without  prior  notice  if  Motient  Services
reasonably  believes  that it must act  immediately  to  protect  the  Satellite
Network and its ability to provide Existing  Satellite  Services and/or to avoid
violations  of law.  In  either  event,  access  to the  Satellite  Network  and
provision  of Service  shall be restored  upon cure by Newco of the event giving
rise to the suspension.

11.3 Termination upon Exercise of Newco Takeover.

This  Agreement  shall  automatically  terminate  on the date of  closing of the
transactions associated with the Newco Takeover.

11.4 Termination Option upon Sale of Existing Business to a Third Party.

If  Motient  Corporation  receives  an  Offer  (as  defined  in the  Asset  Sale
Agreement),  and if Newco  shall  not have  delivered  a Notice to  acquire  the
Satellite  Communications  Business  (as  defined in the Asset  Sale  Agreement)
within sixty (60) days after the Offer Notice Date (as defined in the Asset Sale
Agreement),  and if Motient Corporation or Motient Services elects to pursue the
Offer,  Motient Services shall so notify Newco in writing. If, after electing to
pursue  the  Offer,  the  transactions  contemplated  by the  Offer  fail  to be
consummated,  Motient  Services shall notify Newco in writing of such event,  as
well.  During the period  commencing  on the date of Newco's  receipt of Motient
Services'  notice of the  election  to pursue the Offer and ending on either (i)
the date of consummation of the transactions  contemplated by the Offer, or (ii)
the date of Newco's receipt of written notice that such transactions will not be
consummated  (whichever  applies),  Newco shall refrain from entering enter into
any new Satellite Service agreements with any third party as permitted under the
Commercialization  Agreement,  and from  taking  any action  that would  further
deplete  the  available  Satellite  Network  capacity  or  otherwise  materially
interfere with the  transactions  contemplated  by the Offer.  In the event such
transactions are consummated, Motient Services shall have the right, in its sole
discretion,  and without  consent of Newco,  to terminate  this  Agreement  upon
written notice to Newco and upon compliance with the requirements of Section 8.9
of the Asset Sale Agreement.

11.5 Events upon Termination.

Upon termination of this Agreement pursuant to Section 11.3 or 11.4, Newco shall
immediately  cease  all  access  and use of the  Satellite  Network,  and  shall
promptly,  but in no event less than thirty (30) days after termination,  return
to Motient Services any and all resources provided to Newco by Motient Services,
and remove all Newco Technology from Motient Services' premises and equipment.

                                   ARTICLE xiI

                             LIMITATION OF LIABILITY

12.1 Survival of Representations.

Notwithstanding  anything  to the  contrary  set  forth  in  Section  15.9,  all
representations  and warranties in or pursuant to this  Agreement  shall survive
until  two (2)  years  after  the  date of  expiration  or  termination  of this
Agreement.

12.2 Limitation of Liability.

Motient Services shall in no event be liable for:

          (i) Any Satellite Network service outage or failure; or

          (ii) Any decrease in the excess  capacity of the Satellite  Network or
     of the time  periods in which the  Satellite  Network is made  available to
     Newco to  conduct  the R&D  Activities  as a  result  of  expansion  of the
     Existing Satellite Services in the normal course of business and consistent
     with this Agreement; or

          (iii) The unauthorized access to, or alteration, theft, or destruction
     of  data  and/or   information   of  Newco  by  any  person  other  than  a
     subcontractor  or agent of Motient  Services,  whether through  accident or
     fraudulent  means or  devices,  whether  caused  by  interruption,  errors,
     defects, delays in operation or failure of the Service; or

          (iv) Any claim  arising  out of a breach in the privacy or security of
     communications  transmitted over Motient Services' facilities,  unless such
     breach is caused by Motient Services' willful misconduct; or

          (v) Any change required by any governmental authority to the Satellite
     Network or Motient Services'  facilities,  operations or procedures used in
     connection with the Satellite Network that renders the Satellite Network or
     any such facilities provided by Motient Services or Newco obsolete, or that
     requires Newco to make a material  modification  or alteration of the Newco
     Technology  to  remain  compatible  with  the  Satellite  Network  or  such
     facilities,  or that otherwise  adversely  affect the use or performance of
     the Newco Technology; or

          (vi) Any Loss  incurred  by  reason of or  incidental  to any delay or
     interruption  of the  Service,  other than a delay or  interruption  due to
     Motient Services' willful misconduct; or

          (vii)  Any  failure  by  Motient  Services,   after  exercise  of  all
     commercially reasonable efforts, to obtain and/or maintain any required and
     material FCC or other government approvals for the provision of the Service
     in the Territory;  or the issuance of an effective  final order by the FCC,
     or other government agency having jurisdiction, revoking or denying renewal
     of the mobile satellite services authorization granted to Motient Services.

12.3 Aggregate Damages.

The  Indemnifying   Party  shall  not  be  obligated  to  pay  any  amounts  for
indemnification  under  Article 13 hereof  until the  aggregate  indemnification
obligation  of such  Indemnifying  Party  hereunder  (and  under the Asset  Sale
Agreement)  exceeds  Five-Hundred  Thousand  Dollars  ($500,000) (the "Basket"),
whereupon  the  Indemnifying  Party  shall be liable for all  amounts  for which
indemnification  may  be  sought  which  exceed  $500,000.  Notwithstanding  the
foregoing,  in no event shall the  aggregate  liability  of Motient  Services to
Newco exceed the sum of (i) the aggregate fees  (including the Service Fee) paid
by Newco to Motient Services pursuant to this Agreement, (ii) the Purchase Price
(to the extent actually paid) as defined in the Asset Sale Agreement;  and (iii)
other amounts paid as  consideration  under any  agreements  delivered  pursuant
thereto (collectively,  the sum of (i), (ii) and (iii) constitute the "Liability
Cap").  The  Liability Cap will not apply to any claims made with respect to any
Loss arising as a result of a breach of this Agreement due to Motient  Services'
bad faith or willful misconduct, or to any Losses arising out of a breach of the
representation and warranty set forth in Section 10.1(a)(ii)(x). For purposes of
determining whether the aggregate indemnification  obligation of an Indemnifying
Party exceeds the Basket, the sum of all amounts previously  indemnified by such
Indemnifying  Party for Losses  arising under both this  Agreement and under the
Asset Sale Agreement,  and any agreements  delivered  pursuant  thereto shall be
used to make such determination.

12.4 Exclusive Remedy.

Indemnification  pursuant to Article 13 in accordance with this Article 12 shall
be the  sole  and  exclusive  remedy  for  any  breach  of the  representations,
warranties and covenants contained in this Agreement by either party, other than
claims  relating to fraud or  violations  of  securities  laws;  provided  that,
nothing in this Section 12.4 shall  prevent any party from  obtaining  equitable
relief in order to require the other party to perform its obligations hereunder.

12.5 Limitation of Liability for Motient Services' Suppliers.

To the  extent  that any  portion  of the  Services  or any  facilities  used in
connection  with the Satellite  Network are provided by any third party pursuant
to a separate  agreement  arrangement  between  Motient  Services and such third
party,  the  limitation  of liability  set forth in this Article 12 shall extend
fully to such third party.

                                  ARTICLE xiii

                                    INDEMNITY

13.1 Indemnification by Newco.

Newco shall  indemnify and hold Motient  Services  harmless from and against any
and all Losses  arising out of any claim made by a third party based upon any of
the following:

          (i) The content or addressing of any message  transmitted  by Newco or
     any third party  claim of libel,  slander,  or  infringement  of  copyright
     against   Motient   Services   arising  from  or  in  connection  with  the
     transmission  of  messages  via the  Satellite  Network  by  Newco or third
     parties accessing the Satellite Network through Newco;

          (ii)  Any  negligent  act or  omission  of  Newco,  or  its  officers,
     directors,  employees or agents  resulting in personal  injury or damage to
     tangible or real property; or

          (iii)  Any  breach  by  Newco  of  the   applicable   representations,
     warranties and covenants set forth in this Agreement; or

          (iv) Any portion of the Newco Technology or any portion of the Motient
     Derivative Works (other than the underlying Motient  Technology)  infringes
     the  Intellectual  Property  Rights of a third party;  provided  that Newco
     shall  have  no  obligation  to  indemnify   Motient  Services  under  this
     subsection  (iv) to the extent such an  infringement  claim results  solely
     from  modification of the Newco Technology or the Motient  Derivative Works
     by Motient  Services or any person or entity obtaining access to such Newco
     Technology or Motient Derivative Works through Motient Services.

13.2 Indemnification by Motient Services.

Motient  Services  shall  indemnify and hold Newco harmless from and against any
and all Losses  arising out of any claim made by a third party based upon any of
the following:

          (i)  Any  negligent  act  or  omission  of  Motient  Services,  or its
     officers,  directors,  employees or agents  resulting in personal injury or
     damage to tangible or real property; or

          (ii) Any breach by Motient Services of the applicable representations,
     warranties and covenants set forth in this Agreement; or

          (iii) Any portion of the Motient Technology infringes the Intellectual
     Property Rights of a third party; provided that Motient Services shall have
     no obligation to indemnify Newco under this subsection  (iii) to the extent
     such an  infringement  claim  results  solely from (a) the addition  and/or
     combination by Newco of products not provided by Motient  Services with the
     Motient Technology;  or (b) modification of the Motient Technology by Newco
     or any person or entity obtaining access to such Motient Technology through
     Newco.

13.3 Notification for Indemnification.

All claims for  indemnification  hereunder  shall be resolved in accordance with
the following procedures:

          (i) If the party seeking indemnification (the "Indemnified Party") has
     incurred or  reasonably  believes  that it may incur any  Losses,  it shall
     deliver   promptly   written   notice  to  the   indemnifying   party  (the
     "Indemnifying Party"), setting forth the nature and amount of the Losses or
     potential Losses, if possible, and further referencing the sections of this
     Agreement or in any other document delivered pursuant hereto upon which the
     claim for indemnification  for such Losses is based (a "Claim Notice").  If
     an Indemnified  Party receives  notice of a third-party  claim for which it
     intends to seek indemnification  hereunder,  it shall give the Indemnifying
     Party  written  notice  of such  claim,  so that the  Indemnifying  Party's
     defense of such claim under this  Agreement may be timely  instituted.  The
     failure by an  Indemnified  Party to provide such written  notice shall not
     constitute a waiver of the  Indemnified  Party's right to indemnity  unless
     such failure has prejudiced the Indemnifying Party's ability to defend such
     claim, and then only to the extent of such prejudice.

          (ii) If,  after  receiving  a Claim  Notice,  the  Indemnifying  Party
     desires to dispute such claim or the amount claimed in the Claim Notice, it
     shall deliver to the Indemnified Party a written objection to such claim or
     payment  setting forth the basis for disputing such claim or payment.  Such
     notice shall be delivered  within thirty (30) days after the date the Claim
     Notice to which it relates is received  by the  Indemnifying  Party.  If no
     such  notice is  received  within the  aforementioned  30-day  period,  the
     Indemnified  Party  shall be  entitled  to payment for such Losses from the
     Indemnifying Party within ten (10) days of the end of such 30-day objection
     period.

          (iii) If the Indemnifying Party shall agree that it is responsible for
     all amounts that may be recovered in connection  with a third-party  claim,
     action or suit  (including  waiving  any  deductible  or limit  that  might
     otherwise  apply  under  this  Article 13 or Section  12.3  hereof)  and is
     financially  capable of satisfying  its  indemnification  obligations,  the
     Indemnifying  Party  shall have the right to conduct  and  control  through
     counsel of its own choosing,  which counsel shall be reasonably  acceptable
     to the Indemnified Party, any third-party claim, action or suit;  provided,
     that the Indemnifying Party diligently contests and defends such claim. The
     Indemnified  Party  shall  be  entitled  at any  time,  at its own cost and
     expense   (except  that  such  cost  and  expense  shall  be  paid  by  the
     Indemnifying Party if the Indemnified Party reasonably  determines that the
     Indemnifying Party is not adequately representing or, because of a conflict
     of interest,  may not adequately represent the interests of the Indemnified
     Party) to participate in such defense and to be represented by attorneys of
     its  choosing.  Except with the prior  written  consent of the  Indemnified
     Party no  Indemnifying  Party,  in the defense of such claim or litigation,
     shall consent to entry of any judgment or order,  interim or otherwise,  or
     enter into any settlement that provides for injunctive or other nonmonetary
     relief  affecting  the  Indemnified  Party or that does not  include  as an
     unconditional term thereof the giving by each claimant or plaintiff to such
     Indemnified  Party of a release  from all  liability  with  respect to such
     claim or litigation.

          (iv) In the event that the Indemnifying Party does not elect to defend
     against any third-party  claim,  the  Indemnified  Party may defend against
     such claim in such manner as it may deem  appropriate and the  Indemnifying
     Party  shall be  liable  for any  legal  expenses  reasonably  incurred  in
     connection with such defense;  provided that, the  Indemnified  Party shall
     not, without the consent of the Indemnifying Party, which consent shall not
     be unreasonably  withheld,  settle or consent to the entry of judgment with
     respect to such third-party claim.

          (v) In the event of any claim by a third  party,  the  parties  hereto
     agree that they will cooperate fully with each other in connection with the
     defense or settlement of such matter.

13.4 No Duplication of Remedies.

To the extent any party may have more than one remedy for any Losses incurred by
it, it may pursue all  available  remedies  but in no event shall be entitled to
collect and retain any amount hereunder in excess of its Losses.

13.5 Subrogation.

If any Indemnified Party receives any payment or other indemnification  pursuant
to this Agreement from an Indemnifying Party with respect to any claim or demand
by any third party against the Indemnified  Party, the Indemnifying  Party shall
be subrogated to the extent of such payment or  indemnification to all rights in
respect of the subject  matter of such claim or demand to which the  Indemnified
Party may be entitled, to institute appropriate action for the recovery thereof,
and the Indemnified Party agrees to provide  reasonable levels of assistance and
cooperation to such subrogated party, in enforcing such rights.

                                   ARTICLE xiV

                                   ASSIGNMENT

Motient  Services  shall not  assign  its  rights  and  obligations  under  this
Agreement,  in whole or in  part,  whether  by  operation  of law or  otherwise,
without the prior  written  consent of Newco.  Newco shall not assign its rights
and obligations under this Agreement,  in whole or in part, whether by operation
of law or otherwise,  unless the assignee agrees to be bound by all of the terms
and conditions hereof applicable to Newco hereunder,  and provided that any such
assignment  shall be  subject to any prior  approval  required  by the FCC,  and
compliance with any conditions and restrictions  imposed by the FCC with respect
to such  assignment.  Any  assignment  contrary to the terms of this Article XIV
shall  be null  and  void and of no force  and  effect.  In no event  shall  the
assignment  by Motient  Services or Newco of such party's  respective  rights or
obligations  under this Agreement,  whether before,  at or after the Closing (as
defined  in the Asset Sale  Agreement),  release  such  party from such  party's
respective liabilities and obligations hereunder.

                                   ARTICLE Xv

                            MISCELLANEOUS PROVISIONS

15.1 Successors and Assigns.

This  Agreement  shall be  binding  upon and shall  inure to the  benefit of the
parties  hereto and their  permitted  assigns.  This  Agreement  is entered into
solely for the benefit of such parties.

15.2 No Third Party Beneficiaries.

The provision by Motient  Services to Newco of the Satellite  Network and of the
Services  is not part of any  principal  and agent  relationship,  employer  and
employee relationship,  or joint venture or partnership between Motient Services
and Newco.  This  Agreement  is entered  into  solely for the benefit of Motient
Services and Newco and is for the  exclusive  benefit of such  parties.  Nothing
contained  in  this   Agreement  will  be  deemed  to  create  any  third  party
beneficiaries  or confer  any  benefit or rights on or to any person not a party
hereto,  and no  person  not a  party  hereto  (including,  without  limitation,
customers,  vendors,  or  creditors  of Newco)  shall be entitled to enforce any
provisions hereof or exercise any rights hereunder.

15.3 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 telecopy  addressed as
follows:

     (a) If to Newco:

                           Motient Satellite Ventures LLC
                           10802 Parkridge Boulevard
                           Reston, Virginia  20191-5416
                           Attn:  Randy S. Segal, Esq.
                           Telecopy No.:  703-758-6134

     with a copy to:

                           Motient Satellite Ventures LLC
                           211 North Union Street, Suite 300
                           Alexandria, Virginia  22314
                           Attn:  Hal Perkins
                           Telecopy No.:  703-706-3801

     (b) If to Motient Services:

                           Motient Services Inc.
                           10802 Parkridge Boulevard
                           Reston, Virginia  20191-5416
                           Attn:  Randy S. Segal, Esq.
                           Telecopy No.:  703-758-6134

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  or  telecopied  in the  manner  described  above  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.

15.4 Applicable Law.

This Agreement shall be governed by and construed in accordance with the laws of
the  Commonwealth of Virginia,  without regard to its principles of conflicts of
law  that  would  give  effect  to  the   application  of  the  law  of  another
jurisdiction.  Each of the parties hereto hereby irrevocably and unconditionally
consents  to  submit  to  the  exclusive  jurisdiction  of  the  courts  of  the
Commonwealth  of  Virginia  and of the United  States of  America,  in each case
having  jurisdiction over the County of Fairfax,  for any litigation arising out
of or relating to this Agreement and the  transactions  contemplated  hereby and
thereby (and agrees not to commence any  litigation  relating  thereto except in
such courts), and further agrees that service of any process, summons, notice or
document by U.S.  registered  mail to its  respective  address set forth in this
Agreement  shall be  effective  service of process  for any  litigation  brought
against it in any such court. Each of the parties hereto hereby  irrevocably and
unconditionally  waives any  objection to the laying of venue of any  litigation
arising out of this  Agreement or the  transactions  contemplated  hereby in the
courts of the Commonwealth of Virginia or the United States of America,  in each
case  having  jurisdiction  over the  County  of  Fairfax,  and  hereby  further
irrevocably and  unconditionally  waives and agrees not to plead or claim in any
such court that any such  litigation  brought in any such court has been brought
in an inconvenient forum.

15.5 Waiver.

Neither the waiver by either of the  Parties  hereto of a breach of or a default
under any of the provisions of this Agreement,  nor the failure of either of the
Parties,  on one or more  occasions  to enforce  any of the  provisions  of this
Agreement or to exercise any right or privilege  hereunder  shall  thereafter be
construed as a waiver of any subsequent  breach of default of a similar  nature,
or as a waiver of any provisions,  rights, or privileges  hereunder.  Any waiver
under this Agreement must be in writing.

15.6 Severability.

In the event that any one or more of the provisions of this  Agreement  shall be
held by a court of competent  jurisdiction to be invalid or unenforceable in any
respect,  such  invalidity  and  unenforceability  shall  not  affect  any other
provision of this Agreement, and the Agreement shall be construed as though such
invalid  and/or  unenforceable  provision(s)  had never been  contained  herein,
unless such invalid and/or  unenforceable  provision(s) are an essential part of
the agreed exchange.

15.7 Modification.

No amendment or  modification  to this  Agreement  shall be valid unless made in
writing  and signed by the  authorized  representatives  of the  parties.  As to
Motient Services, the "authorized  representatives" means both Motient Services'
(a) General Counsel and (b) President or any Vice President.

15.8 Headings.

The headings and numbering of paragraphs in this  Agreement are for  convenience
only and shall not be  construed  to define or limit any of the terms  herein or
affect the meaning of interpretation hereof.

15.9 Survival.

The  provisions  of Sections  4.4, 8.1, 8.2, 8.3, 8.4 (to the extent the license
granted therein becomes  perpetual),  8.5, 11.5,  15.2, 15.4, 15.8, and 15.9 and
Articles  V, IX, X (subject to Section  12.1),  XII,  XIII and XV shall  survive
expiration or termination of this Agreement.

15.10 No Joint Venture or Agency.

Neither  Party  will be  deemed  to be an  employee,  agent,  partner  or  legal
representative  of the other for any purpose  and  neither  will have any right,
power or authority to create any obligation or  responsibility  on behalf of the
other.

15.11 Force Majeure.

Motient  Services  shall not be liable  for any  failure of  performance  due to
causes beyond its  reasonable  control,  including,  but not limited to, acts of
God, fires, floods or other catastrophes;  national emergencies,  insurrections,
riots or wars;  strikes,  lockouts,  work stoppages or other labor difficulties;
and any law,  order,  regulation or other action of any  governing  authority or
agency thereof (collectively,  "Force Majeure Events"). A failure of performance
by Motient Services caused solely by acts or omissions of Motient Corporation or
any of  its  Affiliates  (except  to the  extent  such  acts  or  omissions  are
themselves  due to a Force  Majeure  Event) or by reason  of  Motient  Services'
insolvency or bankruptcy or other such condition of financial distress shall not
be deemed to be a Force Majeure Event with respect to Motient Services.

15.12 Entire Agreement.

This Agreement,  including all Schedules  hereto,  and the Asset Sale Agreement,
constitutes the entire  agreement  between the parties hereto and supersedes all
prior oral or written  agreements,  representations,  statements,  negotiations,
understandings,  proposals,  and undertakings with respect to the subject matter
hereof.

<PAGE>

                  IN WITNESS  WHEREOF,  the  Parties  hereto  have  caused  this
Research  and  Development  Agreement  to be executed on the date first  written
above by their duly authorized officers.

                                             MOTIENT SATELLITE VENTURES LLC
                                             By Motient Corporation, Sole Member

                                             By:     /s/Gary M. Parsons
                                                     Gary M. Parsons
                                                     Chairman

                                             MOTIENT SERVICES INC.

                                             By:     /s/Gary M. Parsons
                                                     Gary M. Parsons
                                                     Chairman

<PAGE>

                                   SCHEDULE A

                             FACILITIES REQUIREMENTS

         Newco's  access  to the  Satellite  Network  for the  purposes  of this
Agreement  shall be  subject to its  compliance  with the  following  Facilities
Requirements:

         (1) Compliance with Motient Services requirements and standards:  Newco
will  adhere  to  Motient  Services'  standard   interfacing   requirements  and
specifications  when  interconnecting  external  equipment and facilities to the
Satellite  Network.  Newco's  activities  under this Agreement shall comply with
Motient Services' acceptable use policy and other applicable policies, rules and
regulations (including without limitation those promulgated by the FCC) that are
intended to protect the integrity of the Satellite Network,  to prevent unlawful
or  improper  use of the  Satellite  Network,  and to  prevent  harm to  Motient
Services'  personnel.  Notwithstanding  the generality of the  foregoing,  Newco
shall adhere to Motient Services' IF Interface Access Requirements, as in effect
from  time  to  time.  Motient  Services  reserves  the  right  to  change  such
requirements from time to time, upon reasonable notice to Newco.

         (2) Licenses  and permits:  Newco shall be  responsible  for  obtaining
those licenses,  permits,  rights-of-way,  approvals, and any other arrangements
for which it is  responsible,  as set forth in  Section  6.2.  Motient  Services
agrees to provide Newco with  reasonable  cooperation  and  assistance to enable
Newco to obtain  such  licenses,  permits,  rights-of-way,  approvals  and other
arrangements. Newco agrees that, unless otherwise requested in writing by Newco,
all of Newco's governmental approvals and licensing activities will be conducted
by  Motient  Services'  regulatory  counsel;  provided  that  Motient  Services'
regulatory  counsel will handle requests by Newco for Motient Services to obtain
licenses,   permits,   approvals  and  other  such  items  for  which  Newco  is
responsible, as provided for in Section 6.2.

         (3) Motient  Services  right of access:  For the  protection of Motient
Services'  network,  services,  facilities  and  personnel,  Newco hereby grants
Motient  Services the right at any time, and from time to time,  upon reasonable
prior notice  except in the case of an  emergency,  to inspect all equipment and
communications  facilities  or  services  used or provided by Newco for use with
Motient  Services'  mobile satellite system for compliance with FCC regulations,
this Agreement, and Motient Services' emission requirements, and other technical
requirements.

<PAGE>

                                   SCHEDULE B

                            COMPENSATION FOR SERVICES

Unless agreed otherwise by the parties from time to time, Motient Services shall
be compensated by Newco for the Services to be provided under the Agreement,  in
accordance with this Schedule B.

Motient Services shall not charge Newco for the following Services:

          (i) assistance to Newco in establishing  access and/or connectivity of
     Newco and/or Newco mobile  terminals  and other  equipment to the Satellite
     Network;

          (ii) provision of technical  descriptions of the Satellite Network and
     descriptions   and   explanations  of  Motient   Services'   technical  and
     operational requirements for Newco's use of the Satellite Network;

          (iii) restart of Newco's uplink equipment in the event of an equipment
     failure,  pursuant to  procedures  to be defined in the R&D Support Plan or
     another document; and

          (iv) other similar  services and assistance of a general  nature,  not
     focused on a particular R&D Activity or other special project.

In the event Newco requests in writing for Motient Services to provide any major
or  extraordinary  technical  assistance  required  for Newco to perform its R&D
Activities,  including but not limited to  consulting,  engineering,  strategic,
technical or similar Services provided in support of the R&D Activities, Motient
Services shall be: (a) compensated for Motient  Services  employees at the rates
set forth below, plus reimbursement for reasonable  out-of-pocket  expenses; (b)
compensated for third party  consultants and other personnel  engaged by Motient
Services  for Newco (at written  request of Newco) at Motient  Services'  actual
costs,  plus  reimbursement  for  reasonable   out-of-pocket  expenses  and  (c)
reimbursed,  at Motient Services' cost, for equipment  requested to be purchased
by Newco in connection with the Services.

The billing rates are as follows:
<TABLE>
<CAPTION>

                                                         Hourly Rate
                                                         -----------
<S>                                                         <C>
        Senior  Engineering/
        Technical/Regulatory                                $   135
        Junior Engineering/
        Technical/Regulatory                                $    90
</TABLE>

Motient  Services  shall submit an invoice for all  Services  rendered for which
compensation  is due,  within thirty (30) days following the end of the month in
which  such  Services  were  provided.   Such  invoice  shall  include  a  brief
description  of the Services  rendered,  indicating  the amount charged for each
Service rendered.  Invoices shall be payable by Newco within thirty (30) days of
the invoice date.

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00013-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00013-of-00352.parquet"}]]