DULLES, Va.May 27, 2005--Orbital Sciences Corporation (NYSE:ORB) today stated that U.S. government agents executed search warrants yesterday at its Dulles, VA and Chandler, AZ facilities. Orbital stated that company officials are fully cooperating with the investigative authorities. At this time, the company believes that the investigation is focused on contracting procedures on certain U.S. government launch vehicle programs.

Orbital stated that it strongly supports the U.S. government's procurement integrity processes. The company also stated that it is not aware that it has violated any federal contracting laws, policies or procedures. However, due to the ongoing nature of the investigation, Orbital is unable to make any further statements on the matter at this time.

About Orbital

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 are satellites and launch vehicles, including geostationary and low-orbit 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
             Susan Herlick, 703-406-5002
             Barron Beneski, 703-406-5528

    SOURCE: Orbital Sciences Corporation