For Immediate Release
For More Information Contact:

Barron Beneski (703) 406-5528
Public and Investor Relations

ORBITAL Increases Credit Facility to $450 Million

-- 10-Bank Group Also Extends Maturity to 2017 --

(Dulles, VA 13 December 2012) - Orbital Sciences Corporation (NYSE: ORB) announced today that it completed an amendment to its existing $300 million credit facility providing for a new five-year $150 million senior secured term loan along with an extension of the maturity of the existing senior secured revolving credit facility. Following the amendment and extension, the credit facility borrowing capacity has been increased to $450 million in the aggregate, consisting of the $150 million term loan and $300 million of revolving loan capacity that will both mature in December 2017. All other existing material terms and conditions of the credit facility remain substantially the same.

Proceeds from the term loan will be used to fund the planned retirement of the
company's existing senior subordinated convertible notes and for general corporate purposes. The credit facility is supported by a syndicate of 10 banks led by Wells Fargo Securities LLC, Citigroup Global Markets, Inc. and Merrill Lynch, Pierce, Fenner and Smith Incorporated as Joint Lead Arrangers and Joint Bookrunners.

"We are pleased to announce the closing of this expanded credit facility with our banks which allows us to improve our capital structure and maintain our strong liquidity position," said Mr. Garrett E. Pierce, Orbital's Vice Chairman and Chief Financial Officer. "Further, it gives us significant financial flexibility to support the future growth of our business."

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 Follow the Company on Twitter @OrbitalSciences.

Forward Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 and Section 21E of the Securities Exchange Act of 1934. These forward-looking statements include, but are not limited to, those related to Orbital's financial outlook, liquidity, goals, business strategy, projected plans and objectives of management for future operating results, and forecasts of future events. These statements can be identified by the fact that they do not relate strictly to historical or current facts. Forward-looking statements often include the words "anticipate," "forecast," "expect," "believe," "should," "will," "intend," "plan" and words of similar substance. 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, including impacts of potential sequestration under the Budget Control Act of 2011, new product development programs, product performance and market acceptance of products and technologies, achievement of contractual milestones, government contract procurement and termination risks and income tax rates may materially impact Orbital's actual financial and operational results. Other risks, uncertainties and factors are discussed under "Risk Factors" in the Company's Annual Report on Form 10-K for the year ended December 31, 2011 and the Company's Quarterly Reports on Form 10-Q for the quarters ended June 30, 2012 and September 30, 2012. Orbital is under no obligation to, and expressly disclaims any obligation or undertaking to update or alter any forward-looking statement, whether as a result of new information, subsequent events or otherwise, except as required by law.

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