Orbital Sciences Corporation (NYSE:ORB) today announced that its Board of Directors has authorized the company to repurchase up to $50 million of its common stock over a 12-month period, beginning today. The Board’s authorization will replace a previous $50 million securities repurchase program that expires May 2, 2008, under which Orbital has repurchased $45.2 million of its common stock. Since mid-2004, when Orbital’s buyback program was initiated, the company has repurchased approximately $153 million, or 9.6 million shares, of its common stock for an average purchase price of $15.99 per share.

“The Board’s authorization for another $50 million in common stock repurchases demonstrates Orbital’s commitment to building long-term value for our shareholders through capital structure enhancements, in addition to maintaining the strong operating and financial performance we achieved over the past several years and capitalizing on the encouraging outlook going forward,” said Mr. David W. Thompson, Chairman and Chief Executive Officer.

Under the newly authorized repurchase program, shares of common stock may be purchased from time to time in the open market, in block purchase or in negotiated transactions. The timing and amount of shares to be repurchased will be determined based on market conditions and other factors.

About Orbital

Orbital develops and manufactures small rockets and space systems for commercial, military and civil government customers. The company’s primary products are satellites and launch vehicles, including low Earth-orbit, geosynchronous Earth-orbit and planetary spacecraft for communications, remote sensing, scientific and defense missions; human-rated space systems for Earth-orbit, lunar and other missions; ground- and air-launched rockets that deliver satellites into orbit; and missile defense systems that are used as interceptor and target vehicles. Orbital also offers space-related technical services to government agencies and develops and builds software-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
Barron Beneski, 703-406-5528
Public and Investor Relations
Beneski.barron@orbital.com