<PAGE>   1
                                                                     EXHIBIT 4.9

THIS WARRANT AND THE SHARES OF COMMON STOCK PURCHASABLE HEREUNDER HAVE NOT BEEN
REGISTERED UNDER THE SECURITIES ACT OF 1933 AND MAY NOT BE SOLD OR OFFERED FOR
SALE UNLESS REGISTERED UNDER SAID ACT AND ANY APPLICABLE STATE SECURITIES LAWS
OR UNLESS AN EXEMPTION FROM SUCH REGISTRATION IS AVAILABLE. THIS WARRANT AND THE
SHARES OF COMMON STOCK PURCHASABLE HEREUNDER ARE SUBJECT TO AND HAVE THE BENEFIT
OF A REGISTRATION RIGHTS AGREEMENT DATED AS OF JANUARY 15, 2000 BETWEEN ORBITAL
SCIENCES CORPORATION AND MORGAN GUARANTY TRUST COMPANY OF NEW YORK, AS
ADMINISTRATIVE AGENT, A COPY OF WHICH IS ON FILE WITH ORBITAL SCIENCES
CORPORATION.

                                                         Dated: January 15, 2000


                                     WARRANT

                   TO PURCHASE ______SHARES OF COMMON STOCK OF

                          ORBITAL SCIENCES CORPORATION

                            EXPIRING JANUARY 15, 2005

       THIS IS TO CERTIFY THAT, for value received, ___________________ or
registered assigns ("HOLDER") is entitled to purchase from ORBITAL SCIENCES
CORPORATION, a Delaware corporation ("COMPANY"), at any time or from time to
time after 9:00 a.m., New York City time, on the date hereof and prior to 5:00
p.m., New York City time, on January 15, 2005 at the place where the Warrant
Agency is located, at the Exercise Price, the number of shares of Common Stock
of Company, par value $.01 per share, shown above, all subject to adjustment and
upon the terms and conditions hereinafter provided.

       This Warrant is one of a series of Warrants initially exercisable for an
aggregate of 100,000 shares of Common Stock, all issued pursuant to Amendment
No. 6 dated as of December 21, 1999 to the Credit Agreement.

       Certain terms used in this Warrant are defined in Article 4.


<PAGE>   2

                                    ARTICLE 1

                              EXERCISE OF WARRANTS

       SECTION 1.01. Method of Exercise. To exercise this Warrant, in whole or
in part, the Holder shall deliver on any Business Day to Company, at the Warrant
Agency, (a) this Warrant, (b) a written notice of such Holder's election to
exercise this Warrant, which notice shall specify the number of shares of Common
Stock to be purchased (which shall be a whole number of shares if for less than
all the shares then issuable hereunder), the method of payment elected by the
holder pursuant to clause (c) below, the denominations of the share certificate
or certificates desired and the name or names in which such certificates are to
be registered, and (c) payment of the Exercise Price with respect to such
shares. Such payment may be made, at the option of the Holder, either (a) by
cash, certified or bank cashier's check or wire transfer in an amount equal to
the product of (i) the Exercise Price times (ii) the number of Warrant Shares
for which this Warrant is being exercised or (b) by receiving from Company the
number of Warrant Shares equal to (i) the number of Warrant Shares for which
this Warrant is being exercised minus (ii) the number of Warrant Shares having a
value, based on the average reported closing prices on the five Trading Days
immediately prior to the date of such exercise, equal to the product of (x) the
Exercise Price times (y) the number of Warrant Shares as to which this Warrant
is being exercised.

       Company shall, as promptly as practicable and in any event within seven
days after receipt of such notice and payment, execute and deliver or cause to
be executed and delivered, in accordance with such notice, a certificate or
certificates representing the aggregate number of shares of Common Stock to be
issued pursuant to such notice together with cash in lieu of any fractions of a
share as provided in Section 1.03. The share certificate or certificates so
delivered shall be in such denominations as may be specified in such notice, and
shall be issued in the name of the Holder or such other name or names as shall
be designated in such notice. This Warrant shall be deemed to have been
exercised and such certificate or certificates shall be deemed to have been
issued, and such Holder or any other Person so designated to be named therein
shall be deemed for all purposes to have become a holder of record of shares, as
of the date the aforementioned notice and payment is received by Company. If
this Warrant shall have been exercised only in part, Company shall, at the time
of delivery of such certificate or certificates, deliver to the Holder a new
Warrant evidencing the rights to purchase the remaining shares of Common Stock
called for by this Warrant, which new Warrant shall in all other respects be
identical with this Warrant, or, at the request of the Holder specified in such
notice, appropriate notation may be made on this Warrant which shall then be
returned to the Holder. Company shall pay all expenses, taxes and other charges
payable in connection with the preparation, issuance and delivery of share
certificates and new Warrants, except that, if share certificates or new
Warrants shall be registered in a name or names other than the


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<PAGE>   3


name of the Holder, funds sufficient to pay all transfer taxes payable as a
result of such transfer shall be paid by the Holder at the time of delivery of
the aforementioned notice of exercise or promptly upon receipt of a written
request of Company for payment.

       SECTION 1.02. Shares to Be Fully Paid and Nonassessable. All shares of
Common Stock issued upon the exercise of this Warrant shall be validly issued,
fully paid and nonassessable and, if the Common Stock is then listed on any
national securities exchange or quoted on NASDAQ, shall be duly listed or quoted
thereon, as the case may be.

       SECTION 1.03. No Fractional Shares Required to Be Issued. Company shall
not be required to issue fractions of shares of Common Stock upon exercise of
this Warrant. If any fraction of a share would, but for this Section, be
issuable upon final exercise of this Warrant, in lieu of such fractional share
Company shall pay to the Holder, in cash, an amount equal to the same fraction
of the closing price per share of the Common Stock on the Trading Day
immediately prior to the date of such exercise.

       SECTION 1.04. Share Legend. Each certificate for shares of Common Stock
issued upon exercise of this Warrant, unless at the time of exercise such shares
are registered under the Securities Act, shall bear the following legend:

              "This security has not been registered under the Securities Act of
       1933 and may not be sold or offered for sale unless registered under said
       Act and any applicable state securities laws or unless an exemption from
       such registration is available. This security is also subject to and has
       the benefit of a Registration Rights Agreement dated as of January 15,
       2000 between Orbital Sciences Corporation and Morgan Guaranty Trust
       Company of New York, AS ADMINISTRATIVE AGENT, copies of which are on file
       with Orbital Sciences Corporation."

       Any certificate issued at any time in exchange or substitution for any
certificate bearing such legend (except a new certificate issued upon completion
of a public offering pursuant to a registration statement under the Securities
Act) shall also bear such legend unless, in the opinion of counsel selected by
the holder of such certificate (who may be an employee of such holder) and
reasonably acceptable to Company, the securities represented thereby need no
longer be subject to restrictions on resale under the Securities Act.

       SECTION 1.05. Reservation. Company has duly reserved and will keep
available for issuance upon exercise of the Warrants the total number of Warrant
Shares deliverable from time to time upon exercise of all Warrants from time to
time outstanding.


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<PAGE>   4


                                    ARTICLE 2

         WARRANT AGENCY; TRANSFER, EXCHANGE AND REPLACEMENT OF WARRANTS

       SECTION 2.01. Restrictions on Transfer. Notwithstanding anything
contained in this Warrant, the Warrant may not be transferred except to a Bank
party to the Credit Agreement, or to an affiliate of the transferor or to an
affiliate of such a Bank.

       SECTION 2.02. Warrant Agency. As long as this Warrant remains
outstanding, Company shall perform the obligations of and be the warrant agency
with respect to the Warrant (the "WARRANT AGENCY") at its address set forth on
the signature page or at such other address as Company shall specify by notice
to the Holder.

       SECTION 2.03. Ownership of Warrant. Company may deem and treat the person
in whose name this Warrant is registered as the holder and owner hereof
(notwithstanding any notations of ownership or writing hereon made by any person
other than Company) for all purposes and shall not be affected by any notice to
the contrary, until due presentment of this Warrant for registration of transfer
as provided in this Article 2.

       SECTION 2.04. Transfer of Warrant. Company agrees to maintain at the
Warrant Agency books for the registration of transfers of the Warrant, and
transfer of this Warrant and all rights hereunder shall be registered, in whole
or in part, on such books, upon surrender of this Warrant at the Warrant Agency,
together with a written assignment of this Warrant duly executed by the Holder
or its duly authorized agent or attorney, with (if the Holder is a natural
person) signatures guaranteed by a bank or trust company or a broker or dealer
registered with the NASD, and funds sufficient to pay any transfer taxes payable
upon such transfer. Upon surrender and, if required, such payment, Company shall
execute and deliver a new Warrant or Warrants in the name of the assignee or
assignees and in the denominations specified in the instrument of assignment
(which shall be whole numbers of shares only) and shall issue to the assignor a
new Warrant evidencing the portion of this Warrant not so assigned, if any, and
this Warrant shall promptly be canceled.

       SECTION 2.05. Division or Combination of Warrants. This Warrant may be
divided or combined with other Warrants upon presentment hereof and of any
Warrant or Warrants with which this Warrant is to be combined at the Warrant
Agency, together with a written notice specifying the names and denominations
(which shall be whole numbers of shares only) in which the new Warrant or
Warrants are to be issued, signed by the Holder and the holders thereof or their
respective duly authorized agents or attorneys. Subject to compliance with


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<PAGE>   5


Section 2.03 as to any transfer or assignment which may be involved in the
division or combination, Company shall execute and deliver a new Warrant or
Warrants in exchange for the Warrant or Warrants to be divided or combined in
accordance with such notice.

       SECTION 2.06. Loss, Theft, Destruction of Warrant Certificates. Upon
receipt of evidence satisfactory to Company of the ownership of and the loss,
theft, destruction or mutilation of any Warrant and, in the case of any such
loss, theft or destruction, upon receipt of indemnity or security satisfactory
to Company (it being understood and agreed that if the holder of such Warrant is
A BANK PARTY TO THE CREDIT AGREEMENT, OR AN AFFILIATE OF SUCH A BANK, then a
written agreement of indemnity, reasonably satisfactory to the Company, given by
such holder alone shall be satisfactory to Company and no further security shall
be required) or, in the case of any such mutilation, upon surrender and
cancellation of such Warrant, Company will make and deliver, in lieu of such
lost, stolen, destroyed or mutilated Warrant, a new Warrant of like tenor and
representing the right to purchase the same aggregate number of shares of Common
Stock.

       SECTION 2.07. Expenses of Delivery of Warrants. Company shall pay all
expenses, taxes (other than transfer taxes) and other charges payable in
connection with the preparation, issuance and delivery of Warrants hereunder.

                                    ARTICLE 3

                             ANTIDULUTION PROVISIONS

       SECTION 3.01. Adjustment Generally. The Warrant Share Amount shall be
subject to adjustment from time to time, as follows:

       SECTION 3.02. Common Stock Dividends. In case at any time after the date
hereof, Company shall pay or make a dividend or other distribution on all of its
Common Stock or shall make a dividend or other distribution on any other class
of Capital Stock of Company which dividend or distribution includes Common
Stock, the Warrant Share Amount in effect at the opening of business on the day
following the date fixed for the determination of stockholders entitled to
receive such dividend or other distribution shall be increased by multiplying
such Warrant Share Amount by a fraction of which the denominator shall be the
number of shares of Common Stock outstanding at the close of business on the
date fixed for such determination and the numerator shall be the sum of such
number of shares and the total number of shares constituting such dividend or
other distribution, such increase to become effective immediately after the
opening of business on the day following the date fixed for such determination.


                                       5
<PAGE>   6


For the purposes of this Section 3.02, the number of shares of Common Stock at
any time outstanding shall not include shares held in the treasury of Company
but shall include shares issuable in respect of scrip Common Stock. If any
dividend or distribution of the type described in this Section 3.02 is declared
but not so paid or made, the Warrant Share Amount shall again be adjusted to be
the Warrant Share Amount which would then be in effect if such dividend or
distribution had not been declared.

       SECTION 3.03. Common Stock Rights. In case at any time after the date
hereof, Company shall pay or make a dividend or other distribution on all of its
Common Stock consisting of, or shall otherwise issue to all holders of its
Common Stock, rights, warrants or options (not being available on an equivalent
basis to the Holder of this Warrant upon exercise) entitling the holders of its
Common Stock to subscribe for or purchase Common Stock at a price per share less
than the current market price per share (determined as provided in Section 3.09)
of the shares of Common Stock on the date fixed for the determination of
stockholders entitled to receive such rights, warrants or options (other than
pursuant to a dividend reinvestment plan), the Warrant Share Amount in effect at
the opening of business on the day following the date fixed for such
determination shall be increased by multiplying such Warrant Share Amount by a
fraction of which the denominator shall be the number of shares of Common Stock
outstanding at the close of business on the date fixed for such determination
plus the number of shares of Common Stock which the aggregate of the offering
price of the total number of shares of Common Stock so offered for subscription
or purchase would purchase at such current market price and the numerator shall
be the number of shares of Common Stock outstanding at the close of business on
the date fixed for such determination plus the number of shares of Common Stock
so offered for subscription or purchase, such increase to become effective
immediately after the opening of business on the day following the date fixed
for such determination. For the purposes of this Section 3.03, the number of
shares of Common Stock at any time outstanding shall not include shares held in
the treasury of Company but will include shares issuable in respect of scrip
certificates, if any, issued in lieu of fractions of shares of Common Stock.
Company will not issue any rights or warrants in respect of Common Stock held in
the treasury of Company (or, if rights or warrants are issued in respect of all
of the Common Stock of Company, will not exercise any such rights or warrants in
respect of Common Stock held in the treasury of Company). In the event that such
rights or warrants are not so issued, the Warrant Share Amount shall again be
adjusted to be the Warrant Share Amount which would then be in effect if such
date fixed for the determination of stockholders entitled to receive such rights
or warrants had not been fixed. In determining whether any rights or warrants
entitle the holders to subscribe for or purchase shares of Common Stock at less
than such current market price, and in determining the aggregate offering price
of such


                                       6
<PAGE>   7


shares of Common Stock, there shall be taken into account any consideration
received for such rights or warrants. The value of such consideration, if other
than cash, shall be determined in the reasonable good faith judgment of the
Board of Directors of Company, whose determination shall be conclusive.

       SECTION 3.04. Common Stock Subdivisions and Combinations. In case at any
time after the date hereof, all or any portion of the Common Stock outstanding
shall be subdivided into a greater number of shares of Common Stock, the Warrant
Share Amount in effect at the opening of business on the day following the day
upon which such subdivision becomes effective shall be proportionately
increased, and, conversely in case at any time after the date hereof, all or any
portion of the shares of Common Stock outstanding shall each be combined into a
smaller number of shares of Common Stock, the Warrant Share Amount in effect at
the opening of business on the day following the day upon which such combination
becomes effective shall be proportionately reduced, such increase or reduction,
as the case may be, to become effective immediately after the opening of
business on the day following the day upon which such subdivision or combination
becomes effective.

       SECTION 3.05. Distributions of Property. In case at any time after the
date hereof, Company shall, by dividend or otherwise, distribute to all holders
of its Common Stock evidences of its indebtedness or assets (including
securities, rights, warrants or options, but excluding any rights, warrants, or
options referred to in Section 3.03 as entitling the holders of Common Stock to
subscribe for or purchase Common Stock at a price per share less than the
current market price, any dividend or distribution paid exclusively in cash, any
dividend or distribution referred to in Section 3.02 and any dividend or
distribution upon a merger or consolidation referred to in Section 3.14), the
Warrant Share Amount shall be increased so that the same shall equal the amount
determined by multiplying the Warrant Share Amount in effect immediately prior
to the close of business on the date fixed for the determination of stockholders
entitled to receive such distribution by a fraction of which the denominator
shall be the current market price per share (determined as provided in Section
3.09) of the Common Stock on the date fixed for such determination less the then
fair market value (as determined by the Board of Directors, whose determination
shall be conclusive) of the portion of the assets or evidence of indebtedness so
distributed applicable to one share of Common Stock and the numerator shall be
such current market price per share of the Common Stock, such adjustment to
become effective immediately prior to the opening of business on the day
following the date fixed for the determination of stockholders entitled to
receive such distribution. If any dividend or distribution of the type described
in this Section 3.05 is declared but not so paid or made, the Warrant Share
Amount shall again be adjusted to the


                                       7
<PAGE>   8


Warrant Share Amount which would then be in effect if such dividend or
distribution had not been declared.

       SECTION 3.06. Special Cash Distributions. In case at any time after the
date hereof, Company shall, by dividend or otherwise, make a distribution to all
holders of its Common Stock consisting exclusively of cash (excluding any cash
that is distributed upon a merger or consolidation or a sale or transfer of all
or substantially all of the assets of Company to which Section 3.14 applies or
as part of a distribution referred to in Section 3.05) in an aggregate amount
that, combined together with (i) the aggregate amount of any other distributions
to all holders of its Common Stock made exclusively in cash within the 12 months
preceding the date of payment of such distribution and in respect of which no
adjustment pursuant to this Section 3.06 has been made and (ii) the aggregate of
any cash plus the fair market value (as determined by the Board of Directors,
whose determination shall be conclusive) of consideration payable in respect of
any tender offer by Company or any of its Subsidiaries for all or any portion of
the Common Stock concluded within the 12 months preceding the date of payment of
such distribution and in respect of which no adjustment pursuant to Section 3.07
has been made, exceeds 12.5% of the product of the current market price per
share of Common Stock on the date for the determination of holders of Common
Stock entitled to receive such distribution times the number of shares of Common
Stock outstanding on such date, then, and in each such case, immediately after
the close of business on such date for determination, the Warrant Share Amount
shall be increased so that the same shall equal the rate determined by
multiplying the Warrant Share Amount in effect immediately prior to the close of
business in the date fixed for determination of the stockholders entitled to
receive such distribution by a fraction (A) the denominator of which shall be
equal to the current market price per share (determined as provided in Section
3.09) of the Common Stock on the date fixed for such determination less an
amount equal to the quotient of (x) the excess of such combined amount over such
12.5% and (y) the number of shares of Common Stock outstanding on such date for
determination and (B) the numerator of which shall be equal to the current
market price per share (determined as provided in Section 3.09) of the Common
Stock on such date for determination. If any dividend or distribution of the
type described in this Section 3.06 is declared but not so paid or made, the
Warrant Share Amount shall again be adjusted to the Warrant Share Amount which
would then be in effect if such dividend or distribution had not been declared.

       SECTION 3.07. Tender Offers. In case a tender or exchange offer made by
Company or any Subsidiary for all or any portion of the Common Stock shall
expire and such tender or exchange offer (as amended upon the expiration
thereof) shall require the payment to stockholders (based on the acceptance (up
to any maximum specified in the terms of the tender offer) of Purchased Shares
(as



                                       8
<PAGE>   9
defined below)) of an aggregate consideration having a fair market value (as
determined by the Board of Directors, whose determination shall be conclusive)
that combined together with (i) the aggregate of the cash plus the fair market
value (as determined by the Board of Directors, whose determination shall be
conclusive) as of the expiration of such tender or exchange offer, of
consideration payable in respect of any other tender or exchange offer, by
Company or any Subsidiary of Company for all or any portion of the Common Stock
expiring within the 12 months preceding the expiration of such tender or
exchange offer and in respect of which no adjustment, pursuant to this Section
3.07 has been made and (ii) the aggregate amount of any distributions to all
holders of Company's Common Stock made exclusively in cash within 12 months
preceding the expiration of such tender or exchange offer and in respect of
which no adjustment pursuant to Section 3.06 has been made, exceeds 12.5% of the
product of the current market price per share of the Common Stock (determined as
provided in Section 3.09) as of the last time (the "EXPIRATION TIME") tenders or
tenders could have been made pursuant to such tender or exchange offer (as it
may be amended) times the number of shares of Common Stock outstanding
(including any tendered or exchanged shares) on the Expiration Time, then, and
in each such case, immediately prior to the opening of business on the day after
the date of the Expiration Time, the Warrant Share Amount shall be increased so
that the same shall equal the rate determined by multiplying the Warrant Share
Amount immediately prior to the close of business on the date of the Expiration
Time by a fraction (A) the denominator of which shall be equal to (1) the
product of (x) the current market price per share of the Common Stock
(determined as provided in Section 3.09) on the date of the Expiration Time and
(y) the number of shares of Common Stock outstanding (including any tendered or
exchanged shares) on the date of the Expiration Time less (2) the amount of cash
plus the fair market value (determined as aforesaid) of the aggregate
consideration payable to stockholders based on the acceptance (up to any maximum
specified in the terms of the tender offer) of Purchased Shares, and (B) the
numerator of which shall be equal to the product of (x) the current market price
per share of the Common Stock (determined as provided in Section 3.09), as of
the Expiration Time and (y) the number of shares of Common Stock outstanding
(including any tendered or exchanged shares) as of the Expiration Time less the
number of all shares validly tendered or exchanged and not withdrawn as of the
Expiration Time (the shares deemed so accepted up to any such maximum, being
referred to as the "PURCHASED SHARES"). In the event that Company is obligated
to purchase shares pursuant to any such tender offer, but Company is permanently
prevented by applicable law from effecting any such purchases or all such
purchases are rescinded, the Warrant Share Amount shall again be adjusted to be
the Warrant Share Amount which would then be in effect if such tender offer had
not been made.


                                       9
<PAGE>   10


       SECTION 3.08. Reclassifications. The reclassification of Common Stock
into securities other than Common Stock (other than any reclassification upon a
consolidation or merger to which Section 3.14 applies) shall be deemed to
involve (i) a distribution of such securities other than Common Stock to all
holders of Common Stock (and the effective date of such reclassification shall
be deemed to be "the date fixed for the determination of stockholders entitled
to receive such distribution" and "the date fixed for such determination" within
the meaning of Section 3.05)) and (ii) a subdivision or combination, as the case
may be, of the number of Common Stock outstanding immediately prior to such
reclassification into the number of Common Stock outstanding immediately
thereafter (and the effective date of such reclassification shall be deemed to
be "the day upon which such subdivision becomes effective," as the case may be,
and "the day upon which such subdivision or combination becomes effective",
within the meaning of Section 3.04).

       SECTION 3.09. Current Market Price. For the purpose of any computation
under Section 3.03, 3.05, 3.06 or 3.07, the current market price per share of
Common Stock on any date shall be deemed to be the average of the daily Closing
Prices per share for the five consecutive Trading Days immediately preceding the
earlier of the day in question and the day before the "ex date" with respect to
the issuance or distribution requiring such computation. For purposes of this
paragraph, the term "ex date", when used with respect to any issuance or
distribution, means the first date on which the Common Stock trades regular way
on the applicable securities exchange or in the applicable securities market
without the right to receive such issuance or distribution.

       SECTION 3.10. Certain Limitations. Company hereby covenants not to take
any action (1) to increase the par value per share of the Common Stock, or (2)
that would or does result in any adjustment to the number of shares for which
this Warrant may be exercised that would cause such number to exceed the number
of authorized but unissued shares of Common Stock not reserved for other
purposes.

       SECTION 3.11. Minimum Adjustment. Notwithstanding any of the foregoing
provisions of this Article 3, no adjustment in the Warrant Share Amount need be
made until all cumulative adjustments amount to 1% or more of the Warrant Share
Amount as last adjusted. Any adjustments that are not made shall be carried
forward and taken into account in any subsequent adjustment.

       SECTION 3.12. Notice to Holder. Whenever the Warrant Share Amount is
adjusted as herein provided, Company shall prepare a certificate signed by the
Treasurer of Company setting forth the adjusted Warrant Share Amount showing


                                       10
<PAGE>   11


in reasonable detail the facts upon which such adjustment is based, and such
certificate shall forthwith be delivered to the Holder.

       SECTION 3.13. Deferred Delivery. In any case in which this Article 3
provides that an adjustment shall become effective immediately after a record
date for an event, Company may defer until the occurrence of such event (x)
issuing to the Holder upon exercise of this Warrant after such record date and
before the occurrence of such event the additional shares of Common Stock
issuable upon such exercise by reason of the adjustment required by such event
over and above the Common Stock issuable upon such exercise before giving effect
to such adjustment and (y) paying to such Holder any amount in cash in lieu of
any fractional share of Common Stock pursuant to Section 1.03.

       SECTION 3.14. Merger and Consolidation. In the event that Company shall
be a party to any transaction, including without limitation any (i)
recapitalization or reclassification of the Common Stock (other than a change in
par value, or from par value to no par value, or from no par value to par value,
or as a result of a subdivision or combination of the Common Stock), (ii) any
consolidation of Company with, or merger of the Company into, any other Person,
any merger of another Person into the Company (other than a merger which does
not result in a reclassification, conversion, exchange or cancellation of
outstanding shares of Common Stock of the Company), (iii) any sale or transfer
of all or substantially all of the assets of the Company or (iv) any compulsory
share exchange, pursuant to which the Common Stock is converted into the right
to receive other securities, cash or other property, then lawful provision shall
be made as part of the terms of such transaction whereby the Holder of this
Warrant shall have the right thereafter, to exercise this Warrant for the kind
and amount of securities, cash and other property receivable upon such
recapitalization, reclassification, consolidation, merger, sale, transfer or
share exchange by a holder of the number of shares of Common Stock for which
this Warrant might have been exercised immediately prior to such
recapitalization, reclassification, consolidation, merger, sale, transfer or
share exchange. Company or the person formed by such consolidation or resulting
from such merger or which acquires such assets or which acquires Company's
shares, as the case may be, shall make provisions in its certificate or articles
of incorporation or other constituent document to establish such right. Such
certificate or articles of incorporation or other constituent document shall
provide for adjustments which, for events subsequent to the effective date of
such certificate or articles of incorporation or other constituent document,
shall be as nearly equivalent as may be practicable to the adjustments provided
for in this Article 3. The above provisions shall similarly apply to successive
recapitalization, reclassifications, consolidations, mergers, sales, transfers
or share exchanges.


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<PAGE>   12


                                    ARTICLE 4

                                   DEFINITIONS

       The following terms, as used in this Warrant, have the following
meanings:

       "BUSINESS DAY" means any day excluding Saturday, Sunday and any day on
which banking institutions located in New York are authorized by law or other
governmental action to be closed.

       "CAPITAL STOCK" means (i) in the case of a corporation, corporate stock,
(ii) in the case of an association or business entity, any and all shares,
interests, participations, rights or other equivalents (however designated) of
corporate stock, (iii) in the case of a partnership, partnership interests
(whether general or limited) and (iv) any other interest or participation that
confers on a Person the right to receive a share of the profits and losses of,
or distributions of assets of, the issuing Person.

       "COMPANY" means Orbital Sciences Corporation, a Delaware corporation, and
its successors.

       "CREDIT AGREEMENT" means the Third Amended and Restated Credit and
Reimbursement Agreement dated as of December 21, 1998 among the Company, the
Banks parties thereto and Morgan Guaranty Trust Company of New York, as
Administrative Agent and as Collateral Agent, as amended and in effect from time
to time.

       "EXERCISE PRICE" means $.01 per share of Common Stock.

       "HOLDER" has the meaning set forth in the first paragraph of this
Warrant.

       "NASD" means The National Association of Securities Dealers, Inc.

       "NASDAQ" means The National Association of Securities Dealers, Inc.
Automated Quotation System.

       "PERSON" means any individual, corporation, partnership, joint venture,
association, joint-stock company, trust, unincorporated organization or
government or agency or political subdivision thereof (including any subdivision
or ongoing business of any such entity or substantially all of the assets of any
such entity, subdivision or business).


                                       12
<PAGE>   13


       "SECURITIES ACT" means the Securities Act of 1933, as amended, and rules
and regulations of the Securities and Exchange Commission thereunder.

       "SUBSIDIARY" means any corporation or other entity of which securities or
other ownership interests having ordinary voting power to elect a majority of
the board of directors or other persons performing similar functions are at the
time directly or indirectly owned by the Company (or if such term is used with
reference to any other Person, by such other Person); provided that in no event
shall Orbital Imaging Corporation or ORBCOMM USA L.P., be a "Subsidiary" of the
Company.

       "TRADING DAY" means (x) if the applicable security is listed or admitted
for trading on the New York Stock Exchange or another national securities
exchange, a day on which the New York Stock Exchange or such other national
securities exchange is open for business or (y) if the applicable security is
quoted on the Nasdaq National Market, a day on which trade may be made on the
Nasdaq National Market or (z) if the applicable security is not otherwise
listed, admitted for trading or quoted, any day other than a Saturday or Sunday
or a day on which banking institutions in the State of New York are authorized
or obligated by law or executive order to close.

       "WARRANT AGENCY" has the meaning set forth in Section 2.02.

       "WARRANT SHARES" means the shares of Common Stock issuable upon the
exercise of the Warrants.

       "WARRANT SHARE AMOUNT" means the number of Warrant Shares issuable upon
the exercise of this Warrant.

       "WARRANTHOLDER" means a holder of a Warrant.

       All references herein to "DAYS" shall mean calendar days unless otherwise
specified.

                                    ARTICLE 5

                                  MISCELLANEOUS

       SECTION 5.01. Notices. Notices and other communications provided for
herein shall be in writing and may be given by mail, courier, confirmed telex or
facsimile transmission and shall, unless otherwise expressly required, be deemed
given when received. In the case of the Holder, such notices and communications



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<PAGE>   14
shall be addressed to its address as shown on the books maintained by the
Warrant Agency, unless the Holder shall notify the Warrant Agency that notices
and communications should be sent to a different address (or telex or facsimile
number), in which case such notices and communications shall be sent to the
address (or telex or facsimile number) specified by the Holder. In the case of
the Company, such notices and communications shall be addressed to its address
as shown on the signature pages hereof or to such other address as it may
designate by notice to the Holder and the Administrative Agent.

       SECTION 5.02. Amendments. The provisions of this Warrant may be amended,
modified or waived only with the written consent of Company and the Holder.

       SECTION 5.03. Governing Law. THIS WARRANT SHALL BE CONSTRUED IN
ACCORDANCE WITH AND GOVERNED BY THE LAWS OF THE STATE OF NEW YORK (WITHOUT
REGARD TO PRINCIPLES OF CONFLICTS OF LAW).

       SECTION 5.04. Transfer; Covenants to Bind Successor and Assigns. All
covenants, stipulations, promises and agreements in this Warrant contained by or
on behalf of Company or the Holder shall bind its successors and assigns,
whether so expressed or not. This Warrant shall be transferable and assignable
by the Holder hereof in whole or from time to time in part to any other Person
and the provisions of this Warrant shall be binding upon and inure to the
benefit of the Holder hereof and its successors and assigns.

       SECTION 5.05. No Stockholder Rights. Prior to exercise of this Warrant,
the Holder shall not be entitled to any rights of a stockholder with respect to
the shares of Common Stock purchasable upon exercise, including, without
limitation, the right to vote such shares of Common Stock, receive dividends or
other distributions thereon, exercise preemptive rights or be notified of
stockholder meetings, and, except as explicitly stated herein, the Holder shall
not be entitled to any notice or other communication concerning the business or
affairs of Company.





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<PAGE>   15


       IN WITNESS WHEREOF, Company has caused this Warrant to be executed in its
corporate name by one of its officers thereunto duly authorized, and its
corporate seal to be hereunto affixed, attested by its Secretary or an Assistant
Secretary, all as of the day and year first above written.


                                         ORBITAL SCIENCES CORPORATION

                                         By:
                                            ------------------------------------
                                            Name:
                                            Title:
                                            Address: 21700 Atlantic Boulevard
                                                     Dulles, VA 20166

                                            Attention:  Chief Financial Officer
                                            Telephone No.:
                                            Facsimile No.:


[Corporate Seal]

Attest:


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