DULLES, Va.Nov. 24, 2003--

Overview Presentation and Missile Defense Panel Discussion to be Webcast

Orbital Sciences Corporation (NYSE:ORB) announced today that its Chairman and Chief Executive Officer, David W. Thompson, and Vice Chairman and Chief Financial Officer, Garrett E. Pierce, will participate in the Jefferies Quarterdeck Aerospace, Defense and IT Services conference to be held in New York City at The Grand Hyatt Hotel on December 2. Mr. Thompson and Mr. Pierce will make a presentation to institutional investors on Orbital's current business activities beginning at approximately 9:45 a.m. (EDT). Mr. Thompson will also participate in a panel discussion with other defense industry executives on the topic of U.S. missile defense that will begin at approximately at 2:55 p.m.

Jefferies Quarterdeck will be hosting an audio and presentation slide webcast of the conference, including Orbital's overview presentation and the missile defense panel discussion. The program can be accessed either on Orbital's corporate web site at http://www.orbital.com/Investor/ or at http://event.streamx.us/jefferies/event/default.asp?event=jef20031202

Listeners are encouraged to register in advance and select their preferred Internet media player program prior to the start of the presentation. On the day of the conference, Orbital will make the PowerPoint presentation slides that Mr. Thompson and Mr. Pierce will present to the live audience available on the company's web site. Orbital will also maintain a link to the replay of the conference and will keep the presentation slides available online until December 9.

About Orbital

Orbital develops and manufactures small space systems for commercial, civil government and military customers. The company's primary products are satellites and launch vehicles, including low-orbit, geostationary and planetary spacecraft for communications, remote sensing and scientific missions; ground- and air-launched rockets that deliver satellites into orbit; and missile defense boosters that are used as interceptor and target vehicles. Orbital also offers space-related technical services to government agencies and develops and builds satellite-based transportation management systems for public transit agencies and private vehicle fleet operators.

    CONTACT: Orbital Sciences Corporation
             Barron Beneski, 703-406-5528

    SOURCE: Orbital Sciences Corporation