Company Conducts Eighth Successful Missile Defense Target
                            Vehicle Launch in 2002

DULLES, Va., Dec. 2 /PRNewswire-FirstCall/ -- Orbital Sciences Corporation (NYSE: ORB) announced today that it successfully launched the suborbital rocket that served as the target vehicle for the recent test of the U.S. Missile Defense Agency's (MDA) Aegis Ballistic Missile Defense (Aegis BMD) Program. The launch of Orbital's Target Test Vehicle (TTV) originated from the island of Kauai, Hawaii on November 21. Orbital's role in the test was to supply the TTV rocket and conduct the launch operations under contract to the U.S. Air Force Space and Missile Systems Center. The pre-launch design and engineering work for the TTV mission was accomplished by Orbital's Launch Systems Group at its facility in Chandler, Arizona.

"For the third time this year, Orbital played a critical role in advancing the testing process of the Aegis BMD System being developed by the U.S. Missile Defense Agency," said Mr. Ron Grabe, Orbital's Executive Vice President and General Manager of its Launch Systems Group. "With the success of the TTV flight, Orbital now has launched 8 target vehicles this year, with a 100% success rate, in support of various tests of U.S. defensive missile systems."

Orbital is one of the country's most experienced manufacturers and operators of suborbital boosters and anti-ship cruise missile targets that are used to test defensive weapons systems. In addition to TTV's for the Aegis Ballistic Missile Defense System, Orbital supplies the primary target vehicles for MDA's Ground-based Midcourse Defense System (GMDS). The company also supports other U.S. missile defense programs, with target vehicles for the U.S. Army's PAC-3 and THAAD interceptors and suborbital boosters for the Critical Measurements Program as well as for the U.S. Navy's supersonic ship self-defense systems.

Orbital is one of the world's leading developers and manufacturers of affordable space systems for commercial, civil government and military customers. The company's primary products include low-orbit, geosynchronous and planetary spacecraft for communications, scientific and remote sensing missions; ground- and air-launched rockets that deliver satellites into orbit; and missile defense boosters that are used as target and interceptor vehicles. Orbital also offers space-related technical services to government agencies and develops and builds satellite-based transportation management systems for public transit and public works agencies, as well as private vehicle fleet operators.

More information about Orbital can be found at http://www.orbital.com

CONTACT: Barron Beneski, Public and Investor Relations of Orbital
Sciences Corporation, +1-703-406-5528, Beneski.barron@orbital.com.
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SOURCE Orbital Sciences Corporation

-0- 12/02/2002

/CONTACT: Barron Beneski, Public and Investor Relations of Orbital Sciences Corporation, +1-703-406-5528, or Beneski.barron@orbital.com/