DULLES, Va.April 20, 2005--Orbital Sciences Corporation (NYSE:ORB) today announced that Mr. Gregory A. Jones has recently joined the company in the newly-created position of Vice President of Corporate Strategy and Business Development, reporting directly to Chairman and Chief Executive Officer David W. Thompson. In this new role, Mr. Jones is responsible for leading Orbital's long-range planning, business development and strategic acquisitions efforts in order to expand the company's business into adjacent market areas.

Mr. Jones has spent his entire career in the aerospace industry, first as an engineer in support of military and NASA programs with McDonnell Douglas Corporation, and then in a series of progressively more responsible management, business development and strategic planning positions with both McDonnell Douglas and The Boeing Company.

Most recently, Mr. Jones served as the Senior Director of Business Development for Boeing's Integrated Defense Systems business, a position he held since August 2003. In this role, he was responsible for capturing over $3.5 billion in annual new orders in the markets for national security space and commercial and civil government communications programs. Prior to that position, Mr. Jones served as Boeing's Senior Director of Special Projects for the Space and Intelligence Systems business and was Boeing's Director of Corporate and Strategic Development, located at the company's world headquarters, where he led all mergers and acquisitions, joint ventures and divestitures.

Mr. Jones earned his Masters of Business Administration degree from Pepperdine University in 1990 and also received a Bachelors of Science degree in Aerospace Engineering from San Diego State University in 1985.

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

Note to Editors: A high-resolution photograph (300+ d.p.i.) of Mr. Jones is available on Orbital's web site at: http://www.orbital.com/About/ExecutiveProfiles/

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

    SOURCE: Orbital Sciences Corporation