SCHEDULE 14A
(RULE 14a-101)

INFORMATION REQUIRED IN PROXY STATEMENT

SCHEDULE 14A INFORMATION
PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE SECURITIES
EXCHANGE ACT OF 1934

<Table>

Filed by the Registrant [X]
Filed by a Party other than the Registrant [ ]
Check the appropriate box:

[ ] Preliminary Proxy Statement

[ ] Confidential, for Use of the Commission Only (as
permitted by sec. 14a-6(e)(2))

[X] Definitive Proxy Statement

[ ] Definitive Additional Materials

[ ] Soliciting Material Pursuant to sec. 14a-11(c) or sec. 14a-12
</Table>

ORBITAL SCIENCES CORPORATION
- --------------------------------------------------------------------------------
(Name of Registrant as Specified in Its Charter)

- --------------------------------------------------------------------------------
(Name of Person(s) Filing Proxy Statement if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

[X] No fee required.

[ ] Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and
0-11.

(1) Title of each class of securities to which transaction applies:

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

(2) Aggregate number of securities to which transaction applies:

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(3) Per unit price or other underlying value of transaction computed
pursuant to Exchange Act Rule 0-11 (Set forth the amount on which the
filing fee is calculated and state how it was determined):

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(4) Proposed maximum aggregate value of transaction:

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(5) Total fee paid:

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[ ] Fee paid previously with preliminary materials.

[ ] Check box if any part of the fee is offset as provided by Exchange Act
Rule 0-11(a)(2) and identify the filing for which the offsetting fee
was paid previously. Identify the previous filing by Registration
Statement number, or the Form or Schedule and the date of its filing.

(1) Amount previously paid:

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(2) Form, Schedule or Registration Statement No.:

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(3) Filing party:

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(4) Date filed:

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[ORBITAL LOGO]

March 25, 2002

Dear Stockholder:

It is my pleasure to invite you to the Annual Meeting of Stockholders of
Orbital Sciences Corporation to be held on Thursday, April 25, 2002 at 9:00 a.m.
at our headquarters located at 21839 Atlantic Boulevard, Dulles, Virginia 20166.

Whether or not you plan to attend, and regardless of the number of shares
you own, it is important that your shares be represented at the meeting. You are
urged to sign, date and return your proxy promptly in the enclosed envelope,
which requires no postage if mailed in the United States. Even if you return a
proxy, you may still attend the meeting and vote in person.

I hope that you will be able to attend the meeting. Orbital's officers and
directors look forward to seeing you at that time.

Sincerely,

/s/ DAVID W. THOMPSON
DAVID W. THOMPSON
Chairman of the Board and
Chief Executive Officer

ORBITAL SCIENCES CORPORATION
21839 ATLANTIC BOULEVARD
DULLES, VIRGINIA 20166

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

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS
TO BE HELD APRIL 25, 2002
------------------------

The Annual Meeting of Stockholders of Orbital Sciences Corporation
("Orbital" or the "company"), a Delaware corporation, will be held at our
headquarters located at 21839 Atlantic Boulevard, Dulles, Virginia 20166, on
Thursday, April 25, 2002 at 9:00 a.m. for the following purposes:

1. To elect four directors for three-year terms ending in 2005.

2. To approve an increase in the number of shares authorized to be
issued under the Orbital Sciences Corporation 1999 Employee Stock
Purchase Plan from 1,000,000 shares to 3,000,000 shares.

3. To transact such other business as may properly come before the
meeting or any adjournments thereof.

The Board of Directors has set March 15, 2002 as the record date for the
meeting. This means that owners of our common stock at the close of business on
that date are entitled to receive notice and to vote at the meeting and any
adjournments or postponements thereof.

YOU ARE URGED TO VOTE PROMPTLY BY SIGNING AND RETURNING THE ENCLOSED PROXY CARD.
IF YOU DECIDE TO ATTEND THE MEETING, YOU MAY REVOKE YOUR PROXY AND VOTE YOUR
SHARES IN PERSON.

By Order of the Board of Directors,

/s/ LESLIE C. SEEMAN
LESLIE C. SEEMAN
Executive Vice President, General Counsel
and Secretary

March 25, 2002

ORBITAL SCIENCES CORPORATION
21839 ATLANTIC BOULEVARD
DULLES, VIRGINIA 20166

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

PROXY STATEMENT
ANNUAL MEETING OF STOCKHOLDERS
------------------------

The accompanying proxy is solicited by and on behalf of the Board of
Directors (the "Board") of Orbital Sciences Corporation for use at the Annual
Meeting of Stockholders to be held at our headquarters located at 21839 Atlantic
Boulevard, Dulles, Virginia 20166, on Thursday, April 25, 2002 at 9:00 a.m. and
any adjournments thereof.

The Board has fixed the close of business on March 15, 2002 (the "Record
Date") for determining stockholders who are entitled to vote at the Annual
Meeting of Stockholders. On the Record Date, there were 42,478,231 shares of
common stock, par value $0.01 per share (the "common stock"), outstanding, the
holders of which are entitled to one vote per share on each matter to come
before the meeting. Proxies properly executed and returned will be voted at the
meeting in accordance with any directions noted. Any proxy on which no
directions are indicated will be voted FOR the election of the nominees for
director set forth below and FOR an increase in the number of shares authorized
to be issued under the Orbital Sciences Corporation 1999 Employee Stock Purchase
Plan. Proxies will be voted in the discretion of the holder of the proxy with
respect to any other business that may properly come before the meeting and as
to which a stockholder has not provided timely notice, and all matters
incidental to the conduct of the meeting. Even if you have signed and delivered
a proxy, you may revoke it at any time before it is voted by delivering to the
Secretary of the company a written revocation or a duly executed proxy bearing a
date later than the date of the proxy being revoked. If you attend the meeting
in person, you may revoke your proxy and vote your shares in person.

This Proxy Statement, the accompanying form of proxy, and our Annual Report
on Form 10-K will be mailed to stockholders on or about April 1, 2002.

PROPOSAL 1
ELECTION OF DIRECTORS

Four directors are to be elected at the 2002 Annual Meeting for three-year
terms that expire in 2005. Nine other directors have been elected or appointed
to terms that end in either 2003 or 2004, as indicated below. The term of office
of each nominated director will be for three years expiring at the 2005 Annual
Meeting of Stockholders and until a successor is elected and qualified or until
such director's death, removal or resignation. If any nominees for director
should become unavailable, the Human Resources and Nominating Committee of the
Board would designate substitute nominees and proxies would be voted for such
substitutes. Management does not anticipate that any of the nominees will become
unavailable.

In order to be elected, a nominee must receive the vote of a plurality of
the outstanding shares of common stock represented at the meeting and entitled
to vote. The four nominees for election as directors at the Annual Meeting who
receive the greatest number of votes properly cast for the election of directors
will be elected directors. Shares that are withheld will have no effect on the
outcome of the election.

THE BOARD RECOMMENDS THAT YOU VOTE FOR THE ELECTION OF EACH OF THE NOMINEES
NAMED. Unless instructions are given to the contrary, it is the intention of the
persons named as proxies to vote the shares to which the proxy is related FOR
the election of each of the nominees listed below.

Set forth below is certain information as of March 1, 2002 concerning each
of the nominees and each person whose term of office as a director will continue
after the Annual Meeting.

DIRECTORS TO BE ELECTED AT THE 2002 ANNUAL MEETING

DANIEL J. FINK, 75
Chairman of Audit and Finance Committee and Member of Strategy and Technology
Committee

Daniel J. Fink has been a director of Orbital since 1983. Since 1982, Mr.
Fink has been President of D.J. Fink Associates, Inc., a management consulting
firm. From 1967 until 1982, Mr. Fink held a variety of positions at General
Electric Company, including the position of Senior Vice President from 1979 to
1982. Mr. Fink is a former member of the Defense Science Board and a former
Chairman of the National Aeronautics and Space Administration ("NASA") Advisory
Council. He is a director of Titan Corporation.

ROBERT J. HERMANN, 68
Member of Strategy and Technology Committee

Robert J. Hermann has been a director of Orbital since January 2002, when
he was appointed by the Board. Since 1998, Mr. Hermann has been a Senior Partner
of Global Technology Partners, an aerospace, defense, and technology investment
firm. From 1982 to 1998, Mr. Hermann held a variety of positions at United
Technologies, including the position of Senior Vice President/Science and
Technology from 1987 to 1998. Prior to that time, Mr. Hermann served as Director
of the National Reconnaissance Office, Assistant Secretary of the Air Force for
Research and Development and Logistics, and Principal Deputy Assistant Secretary
of Defense for Communications, Command, Control and Intelligence. He also spent
20 years with the National Security Agency. He is a member of the Defense
Science Board and was Chairman of the Charles Stark Draper Laboratory from 1995
to 2001 and a member of the President's Foreign Intelligence Advisory Board from
1993 to 2001. Mr. Hermann is a director of Condor Systems, Inc.

JANICE I. OBUCHOWSKI, 50
Member of Human Resources and Nominating Committee

Janice I. Obuchowski has been a director of Orbital since 1996. Since 1992,
Ms. Obuchowski has been President of Freedom Technologies, Incorporated, a
telecommunications research and consulting firm. From

1995 until June 1998, Ms. Obuchowski was an Executive Vice President of NextWave
Telecom, Inc. From 1989 to 1992, she served as Assistant Secretary for
Communications and Information at the U.S. Department of Commerce and
Administrator of the National Telecommunications and Information Agency. From
1980 to 1987, Ms. Obuchowski served in a variety of positions at the U.S.
Federal Communications Commission, including Chief of the Common Carrier
Bureau's International Policy Division and Senior Advisor to the Chairman. Ms.
Obuchowski is a director of CSG Systems, Inc.

FRANK L. SALIZZONI, 63
Member of Audit and Finance Committee

Frank L. Salizzoni has been a director of Orbital since 1996. Mr. Salizzoni
was President and Chief Executive Officer of H&R Block, Inc. from 1996 until
2000, and since then has served as Chairman of the Board. From 1994 until 1996,
Mr. Salizzoni was President and Chief Operating Officer of USAir, Inc. and USAir
Group, Inc. He joined USAir as Executive Vice President-Finance and Chief
Financial Officer in 1990. From 1987 to 1989, Mr. Salizzoni was Chairman and
Chief Executive Officer of TW Services, a large food services company. From 1967
to 1987, Mr. Salizzoni held several senior financial management positions with
Trans World Airlines and its parent company, Transworld Corporation. Mr.
Salizzoni is a director of H&R Block, Inc.

DIRECTORS WHOSE TERMS EXPIRE IN 2003

ROBERT M. HANISEE, 63
Member of Audit and Finance Committee

Robert M. Hanisee, CFA, has been a director of Orbital since January 2002,
when he was appointed by the Board. Mr. Hanisee is currently Managing Director
and Chief Investment Officer for Asset Allocation in the Private Client Services
Group of Trust Company of the West. Since 1990, he has held a series of
positions with Trust Company of the West, including Director of Research from
1990 to 1998, managing the Convertible Securities Group from 1992 to 1998, and
Portfolio Manager for the Global Telecom Trust from September 1996 to October
1998. Mr. Hanisee was a founding partner of Amdec Securities, and later was
President of Seidler Amdec Securities. Mr. Hanisee is a director of EDO
Corporation, Illgen Simulation Technologies, Inc. and Titan Corporation.

HARRISON H. SCHMITT, 66
Chairman of Strategy and Technology Committee and Member of Audit and Finance
Committee

Harrison H. Schmitt has been a director of Orbital since 1983. From 1982
until the present, Dr. Schmitt has served in various capacities as a business
and technical consultant. From 1976 to 1982, Dr. Schmitt was a United States
Senator from New Mexico, during which time he chaired the Senate Science,
Technology and Space Subcommittee, which oversees all non-military space-related
research and development programs of the U.S. Government. From 1974 to 1975, he
was Assistant Administrator for Energy Programs for NASA. From 1965 to 1973, he
was a NASA astronaut. As Lunar Module Pilot on Apollo 17 in 1972, he explored
the Moon's surface.

JAMES R. THOMPSON, 65

James R. Thompson, who is not related to David W. Thompson, has been
President and Chief Operating Officer of Orbital since October 1999 and a
director of Orbital since 1992. He is also currently serving as acting General
Manager/Electronic Systems Group. From 1993 until October 1999, Mr. Thompson
served as Executive Vice President and General Manager/Launch Systems Group. Mr.
Thompson was Executive Vice President and Chief Technical Officer of Orbital
from 1991 to 1993. He was Deputy Administrator of NASA from 1989 to 1991. From
1986 until 1989, Mr. Thompson was Director of the Marshall Space Flight Center
at NASA. Mr. Thompson was Deputy Director for Technical Operations at Princeton
University's Plasma Physics Laboratory from 1983 through 1986. Before that, he
had a 20-year career with NASA at the Marshall Space Flight Center. He is a
director of SPACEHAB Incorporated.
3

SCOTT L. WEBSTER, 49

Scott L. Webster is a co-founder of Orbital and has been a director of
Orbital since 1982. Mr. Webster has served as Senior Vice President, Special
Projects of Orbital since May 2001. From 1998 until April 2001, Mr. Webster was
Chairman of the Board and Chief Executive Officer of ORBCOMM Global, L. P.
("ORBCOMM"). From 1993 to 1997, Mr. Webster served in various consulting
capacities with Orbital. He served as President of Orbital's Space Data Division
from 1990 until 1993, and Executive Vice President of that Division from 1989 to
1990. Mr. Webster was Orbital's Senior Vice President/Marketing and Vice
President of Marketing from Orbital's inception in 1982 until 1989. Previously,
he held technical and management positions at Advanced Technology Laboratories
and Litton Industries, Inc.

DIRECTORS WHOSE TERMS EXPIRE IN 2004

LENNARD A. FISK, 58
Member of Strategy and Technology Committee

Lennard A. Fisk has been a director of Orbital since 1993. Since 1993, Dr.
Fisk has been Professor and Chairman of the Department of Atmospheric, Oceanic,
and Space Sciences at the University of Michigan. From 1987 until 1993, he was
Associate Administrator for Space Science and Applications at NASA. From 1977
until 1987, he held various positions at the University of New Hampshire,
including Vice President for Research and Financial Affairs.

RODERICK M. HILLS, 70
Member of Audit and Finance Committee

Roderick M. Hills has been a director of Orbital since November 2001, when
he was appointed by the Board. Mr. Hills serves as Chairman of Hills
Enterprises, Ltd. (formerly the Manchester Group Ltd.), an investment consulting
firm, a position he has held since 1987. He also has been a partner in Hills &
Stern, a law firm, since 1994. From 1978 until 1982, he was a partner and then
of counsel to Latham, Watkins and Hills, a law firm. Mr. Hills served as
Chairman of the Securities and Exchange Commission from 1975 to 1977 and as
counsel to the President of the United States in 1975. Mr. Hills is a director
of Regional Market Makers, Inc. and Chiquita Brands International, Inc.

JACK L. KERREBROCK, 74
Member of Strategy and Technology Committee

Jack L. Kerrebrock has been a director of Orbital since 1993. From 1965
until 2001, Dr. Kerrebrock was a Professor of Aeronautics and Astronautics at
the Massachusetts Institute of Technology. He served as Associate Administrator
for Aeronautics and Space Technology at NASA from 1981 to 1983. From 1984 until
1993, he was a director of Orbital's then wholly owned subsidiary, Orbital
Research Corporation.

GARRETT E. PIERCE, 57

Garrett E. Pierce has been a director of Orbital since August 2000, when he
also joined Orbital as Executive Vice President and Chief Financial Officer.
From 1996 until August 2000, he was Executive Vice President and Chief Financial
Officer of Sensormatic Electronics Corp., where he was also named Chief
Administrative Officer in July 1998. Prior to joining Sensormatic, Mr. Pierce
was the Executive Vice President and Chief Financial Officer of California
Microwave, Inc., a supplier of microwave, radio frequency, and satellite systems
and products for communications and wireless networks. From 1980 to 1993, Mr.
Pierce was employed by Materials Research Corporation, a provider of thin film
equipment and high purity materials to the semiconductor, telecommunications and
media storage industries, where he progressed from Chief Financial Officer to
President and Chief Executive Officer. Materials Research Corporation was
acquired by Sony Corporation as a wholly-owned subsidiary in 1989. From 1972 to
1980, Mr. Pierce held various management positions with AlliedSignal.

DAVID W. THOMPSON, 47
Chairman of the Board

David W. Thompson is a co-founder of Orbital and has been Chairman of the
Board and Chief Executive Officer of Orbital since 1982. From 1982 until October
1999, he also served as President. Prior to founding Orbital, Mr. Thompson was
employed by Hughes Electronics Corporation as special assistant to the President
of its Missile Systems Group and by NASA at the Marshall Space Flight Center as
a project manager and engineer, and also worked on the Space Shuttle's autopilot
design at the Charles Stark Draper Laboratory. Mr. Thompson is a Fellow of the
American Institute of Aeronautics and Astronautics, the American Astronautical
Society and the Royal Aeronautical Society and was recently elected to the U.S.
National Academy of Engineering.

INFORMATION CONCERNING THE BOARD AND ITS COMMITTEES

Meetings and Committees

During 2001, the Board held eleven meetings. The Board has three standing
committees: the Audit and Finance Committee; the Human Resources and Nominating
Committee; and the Strategy and Technology Committee. Each incumbent director,
with the exception of Mr. Webster, attended at least 75 percent of all meetings
of the Board and committees of which he or she was a member. The biographical
information in the immediately preceding section identifies the committee
memberships held by each director.

The Audit and Finance Committee, which held ten meetings in 2001, reviews
the company's financial reports and other information relating to corporate
financial performance and planning, reviews major issues regarding accounting
and auditing principles and practices and significant financial reporting issues
and judgments; oversees internal accounting controls that could significantly
affect financial statements; evaluates financings and financial aspects of
potential acquisitions, divestitures and strategic investments; recommends the
engagement of the company's independent auditors and reviews such auditors'
independence, qualifications, compensation, performance and quality control
procedures; consults with the independent auditors with regard to the plan of
audit; consults with the independent auditors with regard to financial results,
significant accounting policies and issues, and the adequacy of internal
accounting controls; and must approve, in advance, any internal audit services
to be performed by the independent auditor. At the next regularly scheduled
meeting of the Board, Mr. Hills will assume the role of chairman of the
committee.

The Human Resources and Nominating Committee, which held six meetings in
2001, administers Orbital's stock option and stock purchase plans; approves
compensation and, where applicable, severance arrangements for directors,
executive officers and other members of management; evaluates compensation plans
and policies and makes recommendations to the Board with respect thereto;
oversees the defined contribution and deferred compensation plans; considers
issues of corporate governance, management development, evaluation and
succession; reviews corporate human resources matters, including issues relating
to employee benefits and work force recruiting and retention; and nominates
candidates for positions on the Board. In addition, the committee will consider
nominees recommended by stockholders for election as directors if such
recommendations are in writing, are filed with the Secretary of the company by
the time specified in the By-Laws and include the information specified in the
By-Laws. At the next regularly scheduled meeting of the Board, Ms. Obuchowski
will assume the role of chairman of the committee, and the Board expects to
appoint Messrs. Fink, Hanisee and Salizzoni to the committee.

The Strategy and Technology Committee, which held four meetings in 2001,
gives initial Board-level consideration to advanced technology and business
strategy issues, including competitive assessments; reviews and assesses major
programs and research and development activities; evaluates potential
acquisitions, divestitures and joint ventures; and evaluates technical and
market risks associated with new product development.

Director Compensation

During 2001, four directors were salaried employees of Orbital. Such
directors receive no additional compensation for serving on the Board. Board
members who are not salaried employees receive separate compensation for Board
service. In 2001, that compensation included:

(1) an annual retainer in the form of cash or restricted stock;

(2) Board and committee meeting attendance fees in the form of cash or
restricted stock; and

(3) grants of stock options.

All directors also are reimbursed for out-of-pocket expenses in connection with
Board and committee service.

Retainer and Fees. In 2001, nonemployee directors received an annual
retainer of $7,500, along with up to $1,000 for each Board and committee meeting
attended. Such directors had the option during 2001 to elect to receive shares
of restricted common stock under the Orbital Sciences Corporation 1997 Stock
Option and Incentive Plan (the "1997 Option Plan") in lieu of all or a portion
of their annual cash retainer and attendance fees. Nonemployee directors making
this election with respect to their annual retainer received an additional
matching award of an equal number of shares of restricted common stock. The
grants, including the matching award of restricted common stock, vest in their
entirety two years from the date of grant. During 2001, Orbital issued 19,107
shares of restricted common stock in the aggregate to nine nonemployee directors
in lieu of their cash annual retainer. Orbital also issued 21,410 shares of
restricted common stock in the aggregate to six nonemployee directors who
elected to receive restricted common stock in lieu of all of their attendance
fees.

In January 2002, the Board revised its nonemployee director compensation
program to be more consistent with the compensation programs of companies
comparable to Orbital. Commencing in 2002, each nonemployee director will
receive:

(1) an annual retainer of $15,000 paid in shares of restricted common
stock under the 1997 Option Plan; and

(2) a fee of up to $1,000 for each Board and committee meeting attended,
to be paid at the election of such nonemployee director either in
cash or in shares of restricted common stock under the 1997 Option
Plan.

Options and Restricted Stock. Under the 1997 Option Plan, nonemployee
directors receive an automatic annual grant on the first business day in January
of options to purchase common stock at an exercise price equal to the fair
market value on that date. On January 2, 2001, each nonemployee director
received 3,000 common stock options with an exercise price of $4.43 per share.
The option grant vests in its entirety one year from the grant date. Effective
January 1, 2002, the Board amended the 1997 Option Plan to provide for automatic
annual grants of 5,000 stock options to nonemployee directors.

Orbital also matches a nonemployee director's purchase of up to $10,000
worth of common stock in the open market in a calendar year with a grant of
restricted common stock under the 1997 Option Plan. The number of shares of
restricted common stock granted is equal to the dollar value of the nonemployee
director's stock purchase in any given calendar quarter divided by the average
closing sales price of the common stock during that calendar quarter. The grant
vests in its entirety in two years from the date of grant. In January 2002,
Orbital issued 3,636 shares of restricted common stock to one nonemployee
director who participated in the program in the fourth quarter of 2001.

SUMMARY COMPENSATION TABLE

The following table sets forth a summary of all compensation earned,
awarded or paid in the fiscal years ended December 31, 2001, 2000 and 1999, as
applicable, to the Chief Executive Officer, the four most highly compensated
executive officers who were serving as executive officers at December 31, 2001,
and to one individual who would have been one of the most highly compensated
officers but for the fact that he was not serving as an executive officer at
December 31, 2001 (collectively, the "Named Officers").

<Table>
<Caption>
LONG-TERM
COMPENSATION
------------
ANNUAL COMPENSATION SECURITIES
------------------- UNDERLYING ALL OTHER
NAME AND PRINCIPAL POSITION YEAR SALARY BONUS OPTIONS(#) COMPENSATION
- --------------------------- ---- -------- -------- ------------ ------------

David W. Thompson (a).................. 2001 $430,000 $236,448 140,000 $42,032
Chairman of the Board and 75,000(b)
Chief Executive Officer
2000 430,000 -- 75,000 40,336
10,000(b)
1999 415,000 166,000 250,000 17,942
60,000(b)
James R. Thompson (c).................. 2001 400,000 164,964 140,000 39,145
President and Chief Operating Officer 2000 383,000 -- 60,000 37,325
1999 312,000 110,625 50,000 17,942
Garrett E. Pierce (d).................. 2001 400,000 164,964 140,000 155,263
Executive Vice President 2000 400,000 80,000 350,000 60,815
and Chief Financial Officer
Robert D. Strain (e)................... 2001 280,000 443,746 95,000 18,655
Executive Vice President 2000 255,000 654,500 25,000 8,446
and General Manager, Space 1999 240,000 73,100 40,000 11,192
Systems Group
Ronald J. Grabe (f).................... 2001 275,000 183,928 110,000 6,115
Executive Vice President 2000 255,000 -- 60,000 6,087
and General Manager, 1999 240,000 69,800 30,000 5,714
Launch Systems Group
Michael D. Griffin (g)................. 2001 280,000 382,600 60,000 143,877
Former Executive Vice President and 2000 280,000 -- -- 5,600
Chief Technical Officer 1999 280,000 70,000 30,000 9,329
</Table>

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

(a) During 2001, Mr. D. W. Thompson received approximately 50% of his 2001 base
salary in the form of restricted common stock in equal installments granted
on the last trading day of each quarter as follows: 8,958 shares based on a
fair market value of $6.00 per share; 13,853 shares based on a fair market
value of $3.88 per share; 29,532 shares based on a fair market value of
$1.82 per share; and 13,014 shares based on a fair market value of $4.13
per share. He also received $134,968 of his 2001 annual bonus in the form
of 28,474 shares of restricted common stock based on a fair market value of
$4.74 per share on February 5, 2002. Other compensation for Mr. D. W.
Thompson includes company contributions under Orbital's 401(k) plan of
$6,800, $6,400 and $8,000 for 2001, 2000 and 1999, respectively, and under
Orbital's deferred compensation plan of $3,371, $4,031 and $9,942 for 2001,
2000 and 1999, respectively. It also includes partial forgiveness in 2000
of an outstanding loan and accrued interest in the amount of $29,905, and
forgiveness in 2001 of the remaining portion of the loan and accrued
interest of $31,861 pursuant to the company's executive officer loan
program.

(b) Shares of common stock of Orbital Imaging Corporation ("ORBIMAGE"), an
affiliate of the company, underlying options granted under the ORBIMAGE 1996
Stock Option Plan. ORBIMAGE options were granted with an exercise price of
$1.50 per share in 2001, $7.25 per share in 2000 and $6.25 per share in 1999
and vest in equal increments annually over a three-year period from the date
of grant.

(c) During 2001, Mr. J. R. Thompson received approximately 20% of his 2001 base
salary in the form of restricted common stock in equal installments granted
on the last trading day of each quarter as follows: 3,333 shares based on a
fair market value of $6.00 per share; 5,154 shares based on a fair market
value of $3.88 per share; 10,989 shares based on a fair market value of
$1.82 per share; and 4,842 shares based on a fair market value of $4.13 per
share. Mr. J. R. Thompson also received $94,164 of his 2001 annual bonus in
the form of 19,865 shares of restricted common stock based on a fair market
value of $4.74 per share on February 5, 2002. All other compensation for
Mr. J.R. Thompson includes company contributions under Orbital's 401(k)
plan of $6,800, $6,400 and $8,000 for 2001, 2000 and 1999, respectively,
and under Orbital's deferred compensation plan of $484, $1,020 and $9,942
for 2001, 2000 and 1999, respectively. It also includes partial forgiveness
in 2000 of an outstanding loan and accrued interest in the amount of
$29,905, and forgiveness in 2001 of the remaining portion of the loan and
accrued interest of $31,861 pursuant to the company's executive officer
loan program.

(d) Mr. Pierce joined Orbital in August 2000. He received $94,164 of his 2001
annual bonus in the form of 19,865 shares of restricted common stock based
on a fair market value of $4.74 per share on February 5, 2002. All other
compensation for Mr. Pierce includes company contributions under Orbital's
401(k) plan of $6,800 for 2001. It also includes $148,463 and $60,815 as
reimbursement for relocation and living expenses (and the associated income
taxes) in 2001 and 2000, respectively.

(e) Mr. Strain received $56,794 of his 2001 bonus compensation in the form of
11,981 shares of restricted common stock based on a fair market value of
$4.74 per share on February 5, 2002. All other compensation for Mr. Strain
includes company contributions under Orbital's 401(k) plan of $6,800,
$6,400 and $8,000 for 2001, 2000 and 1999, respectively, and under
Orbital's deferred compensation plan of $2,775, $2,046 and $3,192 for 2001,
2000 and 1999, respectively. For 2001, it also included payment of a
transition allowance in the amount of $9,080. Mr. Strain is currently on a
leave of absence.

(f) Mr. Grabe received $62,178 of his 2001 bonus compensation in the form of
13,117 shares of restricted common stock based on a fair market value of
$4.74 per share on February 5, 2002. All other compensation for Mr. Grabe
includes company contributions under Orbital's 401(k) plan of $6,115,
$6,087 and $5,714 for 2001, 2000 and 1999, respectively.

(g) Mr. Griffin resigned from the company in August 2001. All other
compensation for Mr. Griffin includes company contributions under Orbital's
401(k) plan of $3,877, $5,600 and $7,188 for 2001, 2000 and 1999,
respectively, and under Orbital's deferred compensation plan of $0, $0 and
$2,141 for 2001, 2000 and 1999, respectively. It also includes $140,000 of
severance compensation paid in 2001.

OPTION GRANTS IN LAST FISCAL YEAR

The table below shows information on grants of stock options during the
fiscal year ended December 31, 2001 to the Named Officers under the 1997 Option
Plan, which options are reflected in the Summary Compensation Table. The options
granted in 2001 at $4.00 per share vest in equal increments with one-third
vested immediately and the remainder vesting over a two-year period. The options
granted in 2001 at $3.45 per share vest in equal increments over a two-year
period.

<Table>
<Caption>
INDIVIDUAL GRANTS POTENTIAL REALIZED VALUE
-------------------------------------------------- AT ASSUMED ANNUAL RATES
NUMBER OF OF STOCK PRICE
SECURITIES % OF TOTAL APPRECIATION FOR OPTION
UNDERLYING GRANTED TO EXERCISE TERM
OPTIONS EMPLOYEES IN PRICE EXPIRATION -------------------------
NAME GRANTED(#) FISCAL YEAR ($/SHARE) DATE 5% 10%
- ---- ---------- ------------ --------- ---------- ----------- -----------

David W. Thompson........... 100,000 3.2% $4.00 4/24/11 $251,558 $637,497
40,000 1.2% 3.45 12/4/11 88,787 219,936
James R. Thompson........... 100,000 3.2% 4.00 4/24/11 251,558 637,497
40,000 1.2% 3.45 12/4/11 88,787 219,936
Garrett E. Pierce........... 100,000 3.2% 4.00 4/24/11 251,558 637,497
40,000 1.2% 3.45 12/4/11 88,787 219,936
Robert D. Strain............ 60,000 1.9% 4.00 4/24/11 150,935 382,498
35,000 1.1% 3.45 12/4/11 75,939 192,444
Ronald J. Grabe............. 75,000 2.4% 4.00 4/24/11 188,668 478,123
35,000 1.1% 3.45 12/4/11 75,939 192,444
Michael D. Griffin(a)....... 60,000 1.9% 4.00 2/24/03 150,935 382,498
</Table>

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

(a) In connection with his resignation, Mr. Griffin's options continue to vest
under a consulting agreement and will expire on February 24, 2003.

AGGREGATED OPTION EXERCISES DURING 2001 AND DECEMBER 31, 2001 OPTION VALUES

None of the Named Officers exercised stock options during the year ended
December 31, 2001. The table below shows information with respect to the number
of unexercised stock options granted under the 1997 Option Plan and its
predecessor, Orbital's 1990 Stock Option Plan.

<Table>
<Caption>
NUMBER OF UNEXERCISED VALUE OF UNEXERCISED-
OPTION SHARES IN-THE-MONEY OPTIONS
AT DECEMBER 31, 2001 AT DECEMBER 31, 2001
--------------------------- ---------------------------
NAME EXERCISABLE UNEXERCISABLE EXERCISABLE UNEXERCISABLE
- ---- ----------- ------------- ----------- -------------

David W. Thompson............................. 458,334 256,666 $4,333 $35,867
James R. Thompson............................. 258,668 143,332 $4,333 $35,867
Garrett E. Pierce............................. 150,001 339,999 $4,333 $35,867
Robert D. Strain.............................. 146,667 96,666 $2,600 $29,000
Ronald J. Grabe............................... 135,168 115,000 $3,250 $30,300
Michael D. Griffin............................ 90,000 50,000 $2,600 $ 5,200
</Table>

HUMAN RESOURCES AND NOMINATING COMMITTEE REPORT

Overview and Philosophy. The Human Resources and Nominating Committee (the
"Committee") is composed entirely of independent nonemployee directors and is
responsible for evaluating and determining the compensation of the company's
senior executives. The Committee strives to ensure that compensation serves to
motivate and retain senior executives while also being in the best interests of
the company and its stockholders. The Committee's philosophy relating to
executive compensation is to attract and retain highly qualified people at
industry competitive salaries, and to link the financial interests of Orbital's
senior

management to those of the company's stockholders. The Committee endeavors to
attain these goals by tying compensation to the achievement of certain
operational and financial objectives adopted semi-annually by the Committee. To
implement these objectives, the company's compensation structure has five
general components:

(1) base salary;

(2) annual cash and stock incentive bonuses and, under certain
circumstances, special cash bonuses;

(3) stock options and awards of restricted stock;

(4) stock ownership incentives; and

(5) under certain circumstances, stock appreciation rights.

Base Salary. In the early part of each fiscal year, the Committee reviews
with Mr. David W. Thompson, Orbital's Chief Executive Officer, and approves,
with any modifications it deems appropriate, salary levels for the company's
executive officers, including the Named Officers, and certain other members of
senior management. Generally, the salaries are determined subjectively,
intending to reflect the value of the job in the marketplace and the past and
expected future performance and contributions of the individual senior
executive, as well as the company's overall growth and profitability. Because of
the company's liquidity situation, base salaries were not raised in 2001 for
members of senior management, including the Named Officers. Furthermore, in
2001, Messrs. D.W. Thompson and J.R. Thompson volunteered to receive 50% and
20%, respectively, of their base salary in shares of restricted Orbital common
stock that vest on December 31, 2003.

Annual Cash Incentive and Special Bonuses. Under the company's incentive
bonus plan for 2001, the Chief Executive Officer was eligible to receive a bonus
of up to 80% of base salary, and the company's President and Chief Operating
Officer and Chief Financial Officer were each eligible to receive a bonus of up
to 60% of base salary, based on individual achievements and overall company
financial and operational performance. The company's other executive officers,
including the other Named Officers, were eligible to receive annual bonuses of
up to 50% of base salary, based primarily on individual achievements, the
company's financial performance and operating groups' financial and operational
performance or other applicable business unit goals. In January 2001 and July
2001, the Committee reviewed and adopted operational and financial goals
recommended by management for purposes of 2001 bonus opportunities. Financial
goals included achievement of target levels with respect to revenues, earnings
and cash flow. Operational goals included space mission reliability and
timeliness, new orders and contracts, adherence to schedules and budgets, and
the completion of certain corporate transactions.

In July 2001 and January 2002, the Chief Executive Officer evaluated the
company's and the individual groups' performance against the established goals,
and presented his evaluation, together with his reasoning and recommended bonus
percentages to the Committee. The Committee then determined, based on the
recommendations of the Chief Executive Officer and other members of management
and based on any other factors the Committee considered relevant, the percentage
of base salary to be awarded as a bonus to each executive officer. The Committee
concluded that during 2001, the company achieved moderate success in meeting its
operational goals and had mixed success in meeting its financial objectives. The
total bonus percentage awarded to each of the Named Officers (other than the
Chief Executive Officer as described below) was, on average, approximately 60%
of the target bonus amount. The value of the actual bonus was higher, as
described below.

In order to preserve cash, promote employee ownership of stock and retain
key employees, the Committee determined that 50% of the 2001 annual incentive
bonus paid to senior management, including the Named Officers, would be paid in
shares of restricted common stock calculated on the basis of the fair market
value of Orbital's common stock on February 5, 2002. The restricted stock grant
vests in its entirety on January 24, 2003. Employees receiving stock in lieu of
cash for a portion of their annual bonus also received a premium payable in
stock equal to 33% of the value of the stock bonus in order to help offset such
employee's potential income tax liability when the grant vests in 2003. Giving
effect to the stock premium, the value of the

total annual incentive bonus received by the Named Officers (other than the
Chief Executive Officer as described below) was approximately 70% of the target
bonus amount.

In addition to its annual incentive bonus plan, the company also has a
policy of awarding special cash bonuses to an individual or a group in
recognition of exceptional achievement or effort. Mr. Strain received a special
cash bonus in 2001 based on his successful execution of the company's sale of
its Sensor Systems division. Mr. Grabe received a special cash bonus in 2001 in
recognition of achievements by the Launch Systems Group. Mr. Griffin received a
special cash bonus in connection with the company's sale of its Magellan
Corporation subsidiary.

Stock Options. The Committee believes that the award of stock options
provides meaningful long-term incentives that are directly related to the
enhancement of stockholder value. Stock option awards are intended to
incentivize employees to work towards achieving operational and financial goals
that management believes will ultimately be reflected in stock value. The
Committee generally approves an annual grant to senior executives, including the
Named Officers. Under the 1997 Option Plan, stock options are granted at an
exercise price equal to the closing price of the company's common stock on the
date of the grant. Therefore, the value of the grant to the recipient is
directly related to an increase in the price of the common stock. Historically,
option grants have vested in equal increments annually over a three-year period.
However, in April 2001 as in 2000, one-third of the annual grant was immediately
vested, with the remainder vesting equally over a two-year period, in an effort
to increase the retention incentive value of the grant. The Committee also
approved the 2002 annual option grant in December 2001. This option grant will
vest in equal increments annually over a two-year period.

In addition, stock option grants occasionally may be awarded throughout the
year to individuals, including the Named Officers. The number of stock options
granted to each individual is determined subjectively based on a number of
factors, including the individual's degree of responsibility, general level of
performance, ability to affect future company performance, salary level, option
holdings and recent noteworthy achievements.

Stock Ownership Incentives. Intending to incentivize senior management to
increase their equity ownership in the company and thus to further motivate
performance, the Committee has instituted an executive officer loan program that
authorizes the company to make a loan of up to $50,000 to each executive officer
solely for the purpose of purchasing common stock in the open market. Each loan
is for a term of four years with interest deferred. The company has agreed to
forgive one-half of the principal amount and any accrued interest on the third
anniversary of the loan and the other one-half of the principal amount and any
accrued interest on the fourth anniversary of the loan if the executive officer
continues to hold all the shares of stock acquired with the loan proceeds on the
third anniversary of the loan and at least one-half of all such shares on the
fourth anniversary of the loan. In 2001, there were no loans made under this
program.

STOCK APPRECIATION RIGHTS

During 1999, the Committee awarded Performance Share Agreements to the
company's Chief Executive Officer (discussed below), and to Mr. J.R. Thompson,
the company's President and Chief Operating Officer. A similar agreement was
awarded to Mr. Pierce when he joined the company as Executive Vice President and
Chief Financial Officer in August 2000. These agreements are intended to provide
certain executive officers with further incentive to enhance the financial and
operational strength of the company by directly linking a significant component
of their compensation to the amount of appreciation in the company's common
stock. Under these agreements, 50,000 performance shares each were granted to
Mr. J.R. Thompson in 1999 and to Mr. Pierce in 2000. Bonuses are generally
calculated based on the year-to-year increase of the average closing sales price
of the company's common stock for a specified period and are paid into the
officer's account under Orbital's deferred compensation plan, with 50% of the
amount vesting immediately and the remainder vesting one year later. For 2001,
Mr. J.R. Thompson's bonus was based on the amount, if any, by which the average
closing sales price of the company's common stock for the first 20 trading days
of March 2001 exceeded $16.36. Mr. Pierce's bonus was based on the amount, if
any, by which the average closing sales price of the company's common stock for
the 20 trading days preceding August 9, 2001 exceeded $14.41. Based on the

stock price at the measuring dates in 2001, Mr. J.R. Thompson and Mr. Pierce
were not entitled to receive any bonus in 2001 under their respective
Performance Share Agreements.

In 2001, the Committee entered into new Performance Share Agreements with
the company's Chief Executive Officer (discussed below) and Messrs. J.R.
Thompson and Pierce, replacing their existing agreements. Under these
agreements, 60,000 performance shares were granted to each of Mr. J.R. Thompson
and Mr. Pierce providing for a bonus to be paid in 2002 determined by
multiplying the number of performance shares awarded by the increase of the
average closing sales price of the company's common stock for the first 20
trading days of March 2002 over the average closing sales price of the company's
common stock for the first 20 trading days of March 2001. Messrs. J.R. Thompson
and Pierce are eligible for similar bonuses in 2003 under the agreements.
Bonuses earned pursuant to these agreements are paid into the executive
officer's deferred compensation plan account as described above. These
agreements expire on March 31, 2004.

Chief Executive Compensation. As discussed above, because of the company's
liquidity situation at the beginning of 2001, Mr. David W. Thompson's annual
base salary in 2001 was not increased from his 2000 salary of $430,000. The
Committee maintained the Chief Executive Officer's target bonus percentage at
80% of base salary for 2001. The total bonus percentage awarded to the Chief
Executive Officer under the company's incentive bonus plan in 2001 was 59% of
target. The annual incentive bonus paid to the Chief Executive Officer for 2001
was $236,448, or approximately 69% of target, after giving effect to the premium
he received for the stock component of his annual bonus as discussed above. In
determining the Chief Executive Officer's annual incentive bonus, the Committee
considered the Chief Executive Officer's individual performance as well as the
company's financial performance and operating groups' financial and operational
performance. The Committee approved a grant of 100,000 options to Mr. Thompson
in April, 2001 with an exercise price of $4.00 per share, and a grant of 40,000
options in December, 2001 with an exercise price of $3.45 per share, which
options vest as described above.

In 1999, Mr. Thompson was awarded 100,000 performance shares under a
Performance Share Agreement as described above. Under this agreement, Mr.
Thompson's bonus for 2001 was based on the amount, if any, by which the average
closing sales price of the Company's common stock for the first 20 trading days
of March 2001 exceeded $16.36. Based on the stock price at the measuring date in
2001, Mr. Thompson was not entitled to receive any bonus in 2001 under his
Performance Share Agreement.

In 2001, the company entered into a new Performance Share Agreement with
Mr. Thompson replacing his existing agreement and awarding him 80,000
performance shares. Under this agreement, Mr. Thompson is eligible for a bonus
to be paid in 2002 determined by multiplying the number of performance shares
awarded by the increase of the average closing sales price of the company's
common stock for the first 20 trading days of March 2002 over the average
closing sales price of the company's common stock for the first 20 trading days
of March 2001. Mr. Thompson is eligible for a similar bonus in 2003. Bonuses
earned pursuant to this agreement will be paid into Mr. Thompson's deferred
compensation plan account, with 50% of the amount vesting immediately and the
remainder vesting one year later. This agreement expires on March 31, 2004.

The foregoing report has been furnished by the Human Resources and
Nominating Committee members:

Lt. Gen. Kelly H. Burke, Chairman Ms. Janice I. Obuchowski

AUDIT AND FINANCE COMMITTEE REPORT

The Audit and Finance Committee (the "Audit Committee") is responsible for
providing independent, objective oversight of the company's accounting functions
and internal controls. The Audit Committee is comprised of five directors, each
of whom is "independent" as defined by the New York Stock Exchange listing
rules. The Audit Committee operates under a written charter approved by the
Board of Directors.

Management is responsible for the company's internal controls and financial
reporting process. The independent auditors are responsible for performing an
independent audit of the company's consolidated

financial statements in accordance with generally accepted auditing standards
and to issue a report thereon. The Audit Committee's responsibility is to
monitor and oversee these processes.

The Audit Committee has reviewed and discussed the audited consolidated
financial statements of the company for the fiscal year ended December 31, 2001
with the company's management, and also has discussed with
PricewaterhouseCoopers LLP ("PricewaterhouseCoopers"), the company's independent
auditors, the matters required to be discussed by Statement on Auditing
Standards No. 61. The Audit Committee has received both the written disclosures
and the letter from PricewaterhouseCoopers required by Independence Standards
Board Standard No. 1, and has discussed with PricewaterhouseCoopers that firm's
independence.

Based on the Audit Committee's discussions with management and the
independent auditors, the Audit Committee recommended to the Board of Directors
of the company that the audited consolidated financial statements of the company
for the fiscal year ended December 31, 2001 be included in the company's Annual
Report on Form 10-K filed with the SEC on or about March 26, 2002.

The foregoing report has been furnished by the Audit and Finance Committee
members:

<Table>

Mr. Daniel J. Fink, Chairman Mr. Frank L. Salizonni
Mr. Robert M. Hanissee Dr. Harrison H. Schmitt
Mr. Roderick M. Hills
</Table>

STOCKHOLDER RETURN PERFORMANCE PRESENTATION

The following graph compares the yearly cumulative total return on
Orbital's common stock against the cumulative total return on the Nasdaq Stock
Market Index of U.S. Companies and the Dow Jones Aerospace/Defense Index for the
five-year period commencing on December 31, 1996 and ending on December 31,
2001.

COMPARISON OF CUMULATIVE TOTAL RETURNS*

<Table>
<Caption>
NASDAQ US COMPANY DOW JONES ORBITAL SCIENCES
INDEX AREOSPACE/DEFENSE INDEX CORPORATION
----------------- ----------------------- ----------------

December 1997 122 105 172
December 1998 173 97 255
December 1999 321 84 108
December 2000 193 114 24
December 2001 153 95 24
</Table>

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

* Assumes that the value of the investment in Orbital's common stock, the Nasdaq
Stock Market Index of U.S. Companies and the Dow Jones Aerospace/Defense Index
was $100 on December 31, 1996. Orbital has not declared any dividends on its
common stock.

INDEMNIFICATION AGREEMENTS

Orbital has entered into substantially identical indemnification agreements
with each of its directors, the Named Officers and with certain other officers
and senior managers. The agreements provide that Orbital shall, to the full
extent permitted by the Delaware General Corporation Law, as amended from time
to time, indemnify each indemnitee against all loss and expense incurred by the
indemnitee because he or she was, is or is threatened to be made a party to any
completed, pending or threatened action, suit or proceeding by reason of the
fact that he or she was a director, officer, employee or agent of Orbital or any
of its affiliates, or because Orbital has a right to judgment in its favor
because of his or her position with Orbital or any of its affiliates. The
indemnitee will be indemnified so long as he or she acted in good faith and in a
manner reasonably believed by him or her to be in or not opposed to Orbital's
best interest. The agreements further provide that the indemnification
thereunder is not exclusive of any other rights the indemnitee may have under
Orbital's Restated Certificate of Incorporation, By-Laws or any agreement or
vote of stockholders and that the Restated Certificate of Incorporation or
By-Laws may not be amended to affect adversely the rights of the indemnitee.

Orbital also has insurance to indemnify its directors and officers against
certain liabilities, for which it paid approximately $642,000 in premiums in
2001.

EXECUTIVE EMPLOYMENT AGREEMENTS

Orbital has entered into executive employment agreements with its executive
officers, including each of the Named Officers, who are currently employed by
Orbital. These agreements become effective in the event of a "change of
control," as defined in the agreements, of Orbital, and no officer currently
receives compensation under these agreements. Upon a "change of control," each
officer whose employment is terminated by Orbital other than for disability or
"cause," as defined in the agreements, or who terminates his or her employment
for "good reason," as defined in the agreements, within 24 months following such
"change of control," would receive a lump sum equal to two times the sum of his
or her annual base salary plus an amount equal to any bonus paid in the previous
year. In addition, all retirement benefits would vest, all insurance benefits
would continue for 24 months and all Orbital stock options would be repurchased
by Orbital at the difference between the highest price paid in the "change of
control" transaction for shares of stock of the same class or series and the
exercise price of the stock option.

Effective May 1, 2001, Mr. Webster, a director of the company and formerly
President and Chief Executive Officer of ORBCOMM, a former affiliate of
Orbital's, assumed the position of Senior Vice President, Special Projects, of
Orbital. In connection with his employment, Mr. Webster received a $60,000 cash
bonus and $400,000 paid into his account under Orbital's deferred compensation
plan, which amount vests in its entirety on May 1, 2003 or sooner, if he leaves
Orbital's employment for any reason other than for "cause."

In connection with Mr. Griffin's resignation in August 2001 as Executive
Vice President and Chief Technical Officer, Mr. Griffin received a severance
payment of $140,000. In addition, in February 2002, Mr. Griffin received $82,600
representing his pro-rated annual incentive bonus for 2001. He also received a
cash bonus of $200,000 and a $100,000 contribution to his deferred compensation
account in 2001.

RELATED TRANSACTIONS

In September 1999, Mr. Ferguson, a director of the company, exercised his
right under the Orbital Communications Corporation ("OCC") 1992 Stock Option
Plan (the "OCC Option Plan"), to cause OCC to repurchase 7,500 shares of the
32,500 shares of OCC common stock that Mr. Ferguson had acquired upon exercise
of options. OCC is a wholly owned subsidiary of Orbital and was a limited
partner in ORBCOMM in 2000. At that time, OCC tendered to Mr. Ferguson
$163,762.50 cash and a promissory note for $163,762.50 for the repurchase of Mr.
Ferguson's OCC shares. The note bears an annual interest rate of 5.35% and was
due in September 2000. Due to the ORBCOMM bankruptcy, OCC has not repaid the
loan.

PROPOSAL 2
APPROVAL OF AN INCREASE IN NUMBER OF SHARES AUTHORIZED
FOR ISSUANCE UNDER THE ORBITAL SCIENCES CORPORATION
1999 EMPLOYEE STOCK PURCHASE PLAN
FROM 1,000,000 SHARES TO 3,000,000 SHARES

INTRODUCTION

Orbital's stockholders approved its 1999 Employee Stock Purchase Plan (the
"ESPP") at Orbital's 1999 Annual Meeting. The purpose of the ESPP is to enable
eligible employees to purchase shares of Orbital's common stock at a 15%
discount. The Board believes that this is a substantial benefit to employees and
that it will also benefit Orbital by aligning employees' financial interests in
Orbital with those of its stockholders. The ESPP is also intended to benefit
Orbital by increasing employees' interest in its growth and success by providing
an incentive for continued work towards Orbital's financial and operational
goals, and assisting in recruiting and retaining high quality employees. The
ESPP is intended to comply with the terms of Section 423 of the Internal Revenue
Code of 1986, as amended (the "Code").

All 1,000,000 shares of Orbital's common stock authorized for issuance
under the ESPP beginning in 1999 have been purchased by employees.

In January 2002, the Board adopted an amendment to the ESPP to increase the
number of shares of common stock authorized for issuance under the Plan from
1,000,000 to 3,000,000, subject to stockholder approval. The Board believes that
increasing the amount of common stock to be issued under the ESPP will be
adequate for Orbital's near-term needs, and therefore recommends that the
stockholders approve the amendment to the ESPP to effect this increase.

FEATURES OF THE ESPP

Shares subject to the ESPP. The aggregate number of shares of common stock
that currently may be issued and purchased under the ESPP may not exceed
1,000,000 shares, subject to adjustment in the event of certain changes in the
capital structure of Orbital. Shares needed to satisfy purchases under the ESPP
may be authorized but unissued shares or previously issued shares reacquired and
held by Orbital.

Effective date and termination. The ESPP became effective on January 1,
1999, and will terminate on (a) the date on which all shares of common stock
that are available for purchase under the ESPP have been issued or (b) at any
other date at the discretion of the Board.

Administration. The ESPP is administered by the Human Resources and
Nominating Committee of the Board.

Eligibility. Generally, any employee of Orbital is eligible to participate
in the ESPP. As of March 1, 2002, approximately 1,800 employees were eligible to
participate in the ESPP.

Operation of the ESPP. The ESPP permits eligible employees to elect to set
aside a fixed amount, through payroll deductions or otherwise, to purchase
common stock. Generally, payroll deductions will be accumulated during the six
month period (an "Option Period") beginning on the first trading day in January
and ending on the last trading day in June and beginning on the first trading
day in July and ending on the last trading day in December. At the end of each
Option Period, all funds accumulated in a participant's account will be used to
purchase shares of common stock at a purchase price equal to the lesser of 85%
of the fair market value of the common stock (a) on the first trading day of the
Option Period or (b) on the last trading day of such Option Period; provided,
however, that in no event shall the purchase price be less than the par value of
the stock.

Eligible employees enroll in the ESPP at least 15 business days prior to
the commencement of an Option Period. An employee may elect to have deductions
made from his or her eligible compensation or may elect to purchase his or her
shares through a lump sum cash payment, subject to a maximum limit of 20% of
"eligible compensation." "Eligible compensation" is all compensation paid to
such employee plus amounts contributed

by such employee to a retirement plan as an elective deferral under Section
401(k) of the Code, and excludes payments under stock option plans, other
employee benefits plans and bonuses. An eligible employee may terminate payroll
deductions during an Option Period, in which case the amount in such employee's
account will be refunded without interest and the employee's option to purchase
during such Option Period will terminate. No employee may purchase under the
ESPP, together with any other employee stock purchase plans, shares of common
stock having an aggregate fair market value in excess of $25,000 in any calendar
year.

Amendments to the ESPP. The Board may modify the ESPP in any respect, but
must obtain the approval of Orbital's stockholders for any modification that (a)
changes the designation of corporations whose employees may participate in the
ESPP or (b) increases the maximum number of shares subject to purchase under the
ESPP.

United States federal income tax consequences. A participant will not
incur federal income tax as a result of an election to participate in the ESPP
or as a result of the purchase of common stock at the purchase price. A
participant who, either through sale, gift or transfer (other than because of a
corporate reorganization), disposes of common stock at least two years after the
first day of the Option Period during which the shares were acquired under the
ESPP, will recognize (a) ordinary income of an amount equal to the lesser of (i)
the excess of the fair market value of the common stock on the date of
disposition over the price paid for the common stock or (ii) the excess of the
fair market value of the common stock on the first day of the Option Period over
the price paid for the common stock, and (b) long-term capital gain or loss. A
participant who disposes of such shares before two years have expired will have
(a) ordinary income generally equal to the difference between the purchase price
and the fair market value of the common stock on the date of purchase and (b)
long-term or short-term capital gain (depending on how long the participant held
the shares) on the excess, if any, of the fair market value of the common stock
on the date of sale over the purchase price on the date of purchase.

Orbital generally will not be entitled to a business expense deduction in
connection with the sale of shares of common stock under the ESPP, unless a
participant disposes of common stock received under the ESPP before expiration
of the two-year holding period described above. In that case, Orbital will be
entitled to a compensation expense deduction to the extent ordinary income is
recognized by the participant.

The affirmative vote of the holders of a majority of the shares present in
person or represented by proxy and entitled to vote at the meeting will be
required to approve Proposal 2. Abstentions will be considered shares present at
the meeting entitled to vote, but since they are not affirmative votes on the
proposal, will have the same effect as votes against the proposal. Broker
nonvotes will be counted towards a quorum, but are not counted for any purpose
in determining whether the proposal has been approved.

THE BOARD RECOMMENDS THAT YOU VOTE FOR THE APPROVAL OF PROPOSAL 2. Unless
instructions are given to the contrary, it is the intention of the persons named
as proxies to vote the shares to which the proxy is related FOR the approval of
Proposal 2.

OWNERSHIP OF COMMON STOCK

The table below sets forth certain information regarding Orbital's
stock-based holdings as of March 15, 2002 by (1) each person known by Orbital to
own beneficially more than 5% of Orbital's common stock, (2) each director of
Orbital and each Named Officer, and (3) all executive officers and directors as
a group. Unless otherwise indicated, each of the persons or entities listed
below exercises sole voting and investment power over the shares that each of
them beneficially owns.

<Table>
<Caption>
PERCENT OF
SHARES TOTAL SHARES SHARES
BENEFICIALLY AND OPTIONS BENEFICIALLY
NAME AND ADDRESS OWNED (A) OWNED(B) OWNED
- ---------------- ------------ ------------ ------------

FMR Corporation............................................. 4,975,000 4,975,000 11.7%
82 Devonshire Street
Boston, MA 02109(c)
David J. Greene and Company, LLC............................ 3,238,228 3,238,228 7.6%
599 Lexington Avenue
New York, NY 10022(c)
Schneider Capital Management Corporation.................... 2,525,800 2,525,800 5.9%
460 E. Swedesford Road,
Suite 1080
Wayne, PA 19087(c)
Joseph L. Harrosh........................................... 2,229,500 2,229,500 5.2%
40900 Grimmer Blvd
Fremont, CA 94538(c)
Kelly H. Burke.............................................. 66,298 71,298 *
Bruce W. Ferguson(d)........................................ 119,520 124,520 *
Daniel J. Fink(e)........................................... 50,525 55,525 *
Lennard A. Fisk............................................. 36,187 41,187 *
Ronald J. Grabe............................................. 203,518 273,518 *
Michael D. Griffin.......................................... 75,600 105,600 *
Robert M. Hanisee........................................... 7,419 12,419 *
Robert J. Hermann........................................... 2,419 7,419 *
Roderick M. Hills........................................... 2,419 7,419 *
Jack L. Kerrebrock.......................................... 45,516 50,516 *
Janice I. Obuchowski........................................ 24,048 29,048 *
Garrett E. Pierce........................................... 206,661 513,327 *
Frank L. Salizzoni.......................................... 23,861 28,861 *
Harrison H. Schmitt......................................... 27,948 32,948 *
Robert D. Strain............................................ 195,700 264,033 *
David W. Thompson(d)........................................ 670,103 868,436 *
James R. Thompson(d)(e)..................................... 389,483 479,482 *
Scott L. Webster............................................ 197,360 197,360 *
Officers and Directors as a Group (20 persons).............. 2,764,224 3,721,888 6.2%
</Table>

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

* Less than 1%

(a) Includes shares issuable upon exercise of currently vested stock options or
options that will vest within 60 days of March 1, 2002, in the following
amounts: Kelly H. Burke, 22,000 shares; Bruce W. Ferguson, 61,000 shares;
Daniel J. Fink, 24,000 shares; Lennard A. Fisk, 22,000 shares; Ronald J.
Grabe, 180,168 shares; Michael D. Griffin, 70,000 shares; Robert M. Hanisee,
0 shares; Robert J. Hermann, 0 shares; Roderick M. Hills, 0 shares; Jack L.
Kerrebrock, 24,000 shares; Janice I. Obuchowski, 15,000 shares;

Garrett E. Pierce, 183,334 shares; Frank L. Salizzoni, 15,000 shares;
Harrison H. Schmitt, 19,000 shares; Robert D. Strain, 175,000 shares; David
W. Thompson, 516,667 shares; James R. Thompson, 304,001 shares; Scott L.
Webster, 146,000 shares; and all officers and directors as a group,
2,160,837 shares.

(b) Total Orbital stock-based holdings, including shares beneficially owned and
reported on this table and stock options that will not become exercisable
within 60 days of March 1, 2002.

(c) Beneficial ownership is as of December 31, 2001, in each case as based on a
Schedule 13G filed with the Securities and Exchange Commission (the "SEC").

(d) Excludes 12,580 shares of common stock owned by Mr. Ferguson's wife, 23,000
shares of common stock owned by Mr. D.W. Thompson's wife, and 1,385 shares
of common stock owned by Mr. J.R. Thompson's wife. Messrs. Ferguson, D.W.
Thompson and J.R. Thompson disclaim beneficial ownership of such shares.

(e) Includes 2,000 shares of common stock with respect to which Mr. Fink shares
voting and investment power with his wife, and 16,374 shares of common stock
with respect to which Mr. J.R. Thompson exercises voting and investment
power on behalf of a trust.

SECTION 16(A) BENEFICIAL OWNERSHIP REPORTING COMPLIANCE

Section 16(a) of the Securities and Exchange Act requires Orbital's
executive officers and directors, and persons who beneficially own more than 10%
of Orbital's common stock, to file reports of ownership and changes in ownership
on Forms 3, 4 and 5 with the SEC. Executive officers, directors and greater than
10% stockholders are required by SEC regulation to furnish to Orbital copies of
all Forms 3, 4 and 5 they file. Based solely on Orbital's review of the copies
of such forms it has received and written representations from certain reporting
persons, Orbital believes that all its executive officers and directors complied
with the filing requirements applicable to them with respect to transactions
during fiscal year 2001.

RELATIONSHIP WITH INDEPENDENT AUDITORS

The Board has selected the firm of PricewaterhouseCoopers as Orbital's
independent auditors for the fiscal year ending December 31, 2002.
PricewaterhouseCoopers has served as Orbital's independent auditors since 1999.
Representatives of PricewaterhouseCoopers are expected to be present at the
Annual Meeting and will be available to respond to appropriate questions and
make a statement if they so desire.

FEES OF INDEPENDENT AUDITORS FOR CALENDAR
YEAR ENDED DECEMBER 31, 2001

For services rendered during or in connection with Orbital's fiscal year
ending December 31, 2001, Orbital has received, or expects to receive, invoices
from PricewaterhouseCoopers for the following fees:

<Table>

Audit Fees (a).............................. $1,162,395
Financial Information Systems
Design and Implementation Fees.............. $ 0
All Other Fees (b).......................... $ 177,315
</Table>

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

(a) Audit fees include services rendered for the annual audit of Orbital's
consolidated financial statements and the quarterly reviews of the
consolidated financial statements in Orbital's Forms 10-Q for the first
three quarters of 2001.

(b) Other fees consisted primarily of tax compliance services, audits of benefit
plans, and other non-financial statement audit services.

The Audit and Finance Committee takes into consideration all other fees
charged by the independent auditors in its assessment of PricewaterhouseCooper's
independence.

STOCKHOLDER PROPOSALS FOR 2003 PROXY STATEMENT

Stockholder proposals that are intended to be included in the proxy
statement and related proxy materials for Orbital's 2003 Annual Meeting of
Stockholders must be received by Orbital no later than December 2, 2002 at its
principal office, 21839 Atlantic Boulevard, Dulles, Virginia 20166, Attention:
Corporate Secretary.

In addition, the proxy solicited by the Board for the 2003 Annual Meeting
of Stockholders will confer discretionary authority to vote on any stockholder
proposal presented at that meeting, unless Orbital is provided with notice of
such proposal by February 15, 2003.

OTHER MATTERS

Management has no knowledge of any other matter that may come before the
Annual Meeting and does not, itself, currently intend to present any such other
matter. However, if any such other matter properly comes before the meeting or
any adjournments thereof, the persons named as proxies will have discretionary
authority to vote the shares represented by the accompanying proxy in accordance
with their own judgment.

PROXY SOLICITATION

The cost of soliciting proxies will be paid by Orbital. Proxies may be
solicited without extra compensation by certain directors, officers and regular
employees of Orbital by mail, telephone or in person. In addition, Orbital has
retained D.F. King & Co. ("D.F. King") to solicit proxies and to request
brokerage houses and other custodians, nominees and fiduciaries to forward proxy
materials to the beneficial owners of common stock. Orbital will pay D.F. King a
fee not to exceed $4,000 covering its services and, in addition, will reimburse
D.F. King for expenses and payments made for Orbital's account to brokers and
other nominees for their expenses in forwarding soliciting material.

Stockholders are urged to send their proxies without delay. Your
cooperation is appreciated.

ORBITAL SCIENCES CORPORATION

Proxy for Annual Meeting of Stockholders - April 25, 2002

THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS

The undersigned appoints David W. Thompson and Leslie C. Seeman and each
of them as proxies, with power of substitution and re-substitution to each, to
vote at the annual meeting of stockholders of Orbital Sciences Corporation (the
"company") to be held at the company's headquarters, 21839 Atlantic Boulevard,
Dulles, Virginia 20166 on April 25, 2002 at 9:00 a.m. and at any adjournments
thereof, all shares of stock of the company that the undersigned would be
entitled to vote if personally present. A majority of said proxies or their
substitutes or re-substitutes or any one if only one is present and acting,
shall have all the powers of all said proxies. The undersigned instructs said
proxies, or their substitutes or re-substitutes, to vote in such manner as they
may determine on any matters that may properly come before the meeting as
indicated in the Notice of Annual Meeting and Proxy Statement, receipt of which
is hereby acknowledged, and to vote as specified by the undersigned on the
reverse side.

THIS PROXY, WHEN PROPERLY EXECUTED, WILL BE VOTED AS DIRECTED, OR IF NO
DIRECTION IS MADE, FOR THE ELECTION OF THE NAMED NOMINEES AS DIRECTORS AND FOR
PROPOSAL 2.

THE BOARD OF DIRECTORS RECOMMENDS A VOTE FOR ALL DIRECTOR NOMINEES AND
PROPOSALS 1 AND 2.

1. To elect four Directors, each to serve for a three-year term ending in
2005.

Nominees: Daniel J. Fink, Robert J. Hermann, Janice I. Obuchowski and
Frank L. Salizzoni

[ ] FOR ALL [ ] WITHHOLD ALL

--------------------------------------------
[ ] FOR ALL NOMINEES EXCEPT AS NOTED ABOVE
(Instruction: To withhold authority to vote for any nominee(s), write
the name(s) of such nominee(s) above.

................................................................................

2. To approve an increase in the number of shares authorized to be issued
under Orbital Sciences Corporation 1999 Employee Stock Purchase Plan
from 1,000,000 shares to 3,000,000 shares.

FOR AGAINST ABSTAIN
................................................................................

Please vote, date and promptly return this proxy in the enclosed return
envelope, which is postage prepaid if mailed in the United States.

Dated: _________________________, 2002

___________________________________ For Inspector of
Signature Elections' Use Only

___________________________________ ____________________
Name (please print) Number of Shares

Please sign exactly as your name appears hereon. If the stock is registered in
the names of two or more persons, each should sign. Executors, administrators,
trustees, guardians and attorneys-in-fact should add their titles. If signer is
a corporation, please give full corporate name and have an authorized officer
sign, stating title. If signer is a partnership, please sign in partnership name
by authorized person.