DULLES, Va.Aug. 26, 2003--Orbital Sciences Corporation (NYSE:ORB) announced today that it has commenced an offer to exchange its 9% Senior Notes due 2011, which were sold in July 2003 pursuant to Rule 144A and Regulation S of the Securities Act of 1933, as amended (the "Securities Act"), for an equal amount of newly issued 9% Senior Notes due 2011. The new notes have substantially the same terms as the original notes, except that the new notes have been registered under the Securities Act and will be available for trade.

Orbital will accept for exchange any and all original notes validly tendered and not withdrawn prior to 5:00 p.m. New York City time on September 24, 2003 (the "expiration date"), unless extended. Tenders of original notes may be withdrawn at any time prior to 5:00 p.m. New York City time on the expiration date.

The terms of the exchange offer and other information relating to Orbital are set forth in the prospectus dated August 25, 2003. Copies of the prospectus and the related letter of transmittal may be obtained from U.S. Bank National Association, which is serving as the exchange agent in connection with this exchange offer. U.S. Bank's address, telephone number and facsimile number are as follows:

    U.S. Bank National Association
    60 Livingston Avenue
    St. Paul, MN 55107-2292
    Attention: Corporate Trust Department
    Phone: (651) 495-3913
    Facsimile: (651) 495-8097

This press release shall not constitute an offer to exchange nor a solicitation of an offer to exchange the original notes. The exchange offer is made only by the prospectus dated August 25, 2003.

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.

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

    CONTACT: Orbital Sciences Corporation
             Public and Investor Relations
             Barron Beneski, 703-406-5528

    SOURCE: Orbital Sciences Corporation