1
                                                                  EXHIBIT 10.1.3



                                 AMENDMENT NO. 3
                                       TO
                           SECOND AMENDED AND RESTATED
                       CREDIT AND REIMBURSEMENT AGREEMENT


            AMENDMENT No. 3 dated as of June 18, 1998 among ORBITAL SCIENCES
CORPORATION (the "Company"), MORGAN GUARANTY TRUST COMPANY OF NEW YORK, the
BANKS listed on the signature pages hereof and MORGAN GUARANTY TRUST COMPANY OF
NEW YORK, as Administrative Agent (the "Administrative Agent") and as Collateral
Agent.


                             W I T N E S S E T H:


            WHEREAS, the parties hereto have heretofore entered into a Second
Amended and Restated Credit and Reimbursement Agreement dated as of August 5,
1997 (as amended from time to time, the "Credit Agreement"); and

            WHEREAS, the parties hereto wish to amend the terms of the Credit
Agreement as set forth herein;

            NOW, THEREFORE, the parties hereto agree as follows:

            SECTION 1. Definitions; References. Unless otherwise specifically
defined herein, each term used herein that is defined in the Credit Agreement
shall have the meaning assigned to such term in the Credit Agreement. Each
reference to "hereof", "hereunder", "herein" and "hereby" and each other similar
reference and each reference to "this Agreement" and each other similar
reference contained in the Credit Agreement shall from and after the Amendment
Effective Date (as defined in Section 4 below) refer to the Credit Agreement as
amended hereby.

            SECTION 2. Additional Permitted Investment. Section 5.07 of the
Credit Agreement is amended by (i) deleting the "and" at the end of the clause
(k) thereof, (ii) changing the reference to "clause (l)" contained in clause (l)
to "clause (m)", (iii) renumbering clause (l) thereof as clause (m) and (iv)
adding a new clause (l) immediately after clause (k) thereof to read in its
entirety as follows:


   2


            (l) (i) Investments by the company or any of its Subsidiaries in an
      aggregate amount not to exceed $50,000,000 and consisting of shares of
      capital stock of CCI International N.V. ("CCI"), a company formed and
      existing under the laws of the Netherlands Antilles, made at any date (x)
      on or after the date on which the Company and CCI shall have entered into
      a Space Segment Contract substantially on the terms described by the
      Company to the Banks prior to June 18, 1998 and pursuant to which the
      Company shall have been appointed as the general contractor for the
      design, implementation and use of a low-Earth orbit satellite-based
      digital telephone system and prior to December 31, 1998, (ii) Investments
      (other than Investments permitted pursuant to clause (i)) in an aggregate
      amount up to $50,000,000 and consisting of shares of capital stock of CCI
      made on any date after December 31, 1998 and on or prior to June 31, 2000;
      provided that (l) prior to making any such Investment, the aggregate
      amount of Investments permitted pursuant to clause (i) has been made and
      (2) on any date (an "Investment Date") immediately after giving effect to
      any such proposed Investment, the Company is in pro forma compliance with
      the covenants set forth in Sections 5.08, 5.09 and 5.10, after giving
      effect to such proposed Investment (and for such purposes, "Consolidated
      EBITDA" and "Earnings Available for Fixed Charges" shall be calculated for
      the period of four consecutive fiscal quarters most recently ended on or
      prior to such Investment Date, adjusted to give effect to such proposed
      Investment), (iii) Investments by the Company or any of its Subsidiaries
      consisting of warrants exercisable for the capital stock of CCI; provided
      that (1) such warrants are acquired contemporaneously with the making of
      any Investment permitted by clause (ii), (2) no cash consideration is paid
      by the Company or any of its Subsidiaries for the acquisition of any such
      warrants and (3) such warrants are substantially on the terms described by
      the Company to the Banks prior to June 18, 1998 and (iv) Investments by
      the Company or any of its Subsidiaries in CCI constituting "vendor
      financing" substantially on the terms described by the Company to the
      Banks prior to June 18, 1998.

            SECTION 3. New York Law. This Amendment shall be governed by and
construed in accordance with the laws of the State of New York.

            SECTION 4. Counterparts; Effectiveness. This Amendment may be signed
in any number of counterparts, each of which shall be an original, with the same
effect as if the signatures thereto and hereto were upon the same instrument.
This Amendment shall become effective on the date (the "Amendment Effective
Date") on which the Administrative Agent shall have received duly executed
counterparts hereof signed by the Company and the Banks (or, in the case of any
party as to which an executed counterpart shall not have been received, the
Administrative Agent shall have received telegraphic, telex or other written
confirmation from such party of execution of a counterpart hereof by such
party).


                                       2
   3


IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be duly
executed as of the date first above written.


                                      ORBITAL SCIENCES CORPORATION



                                      By     /s/  Kenneth Sunshine
                                        ----------------------------------------
                                        Title: Vice President and Treasurer



                                      MORGAN GUARANTY TRUST COMPANY OF NEW YORK



                                      By     /s/  Diana H. Imhof
                                        ----------------------------------------
                                        Title: Vice President



                                      THE BANK OF NOVA SCOTIA



                                      By    /s/  Barry Luter
                                        ----------------------------------------
                                        Title: Division Head



                                      NATIONSBANK, N.A.



                                      By    /s/  Michael Brick
                                        ----------------------------------------
                                        Title:  Vice President


                                       3