-- Company Signals Confidence in Its Long-Term Business Outlook --

DULLES, Va., Apr 23, 2010 (BUSINESS WIRE) --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. The new stock repurchase authorization replaces the previous $50 million authorization that expired on March 6, 2010. Since Orbital began its share repurchase program in 2004, the company has repurchased 12,772,038 shares for a total of $207,339,898.

"The Board's authorization for another $50 million in common stock repurchases in 2010 and early 2011 reflects our commitment to long-term shareholder value and our optimistic outlook for the company's future business prospects," said Mr. David W. Thompson, Chairman and Chief Executive Officer. "With a strong balance sheet and cash flows that are projected to be robust in future years, we will continue to pursue our three-part capital deployment strategy that includes internal investments in product development for organic growth, possible future acquisitions and selective stock repurchases. The Board's new authorization allows us to continue this successful strategy for another year."

Under the newly authorized repurchase program, shares of common stock may be purchased from time to time in the open market, in block purchases 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- and medium-class 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 exploration 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 provides satellite subsystems and space-related technical services to U.S. Government agencies and laboratories.

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

"Safe Harbor" Statement Under the Private Securities Litigation Reform Act of 1995

Certain statements in this press release may be forward-looking in nature or "forward-looking statements" as defined in the Private Securities Litigation Reform Act of 1995. Such forward-looking statements are subject to risks, trends and uncertainties that could cause the actual results or performance of the company to be materially different from the forward-looking statement. Uncertainty surrounding factors such as continued government support and funding for key space and defense programs, new product development programs, product performance and market acceptance of products and technologies, government contract procurement and termination risks as well as other risk factors and business considerations described in the company's SEC filings, including its annual report on Form 10-K, could impact Orbital's actual financial and operational results. Orbital assumes no obligation for updating the information contained in this press release.

SOURCE: Orbital Sciences Corporation

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