DULLES, Va., Dec 13, 2006 (BUSINESS WIRE) -- Orbital Sciences Corporation (NYSE: ORB) today announced that it closed its previously announced sale of $143.75 million 2-7/16% convertible senior subordinated notes due 2027, which includes the exercise in full by the initial purchasers of their over-allotment option to purchase up to an additional $18.75 million aggregate principal amount of the notes. The company also has completed the repurchase of 2,655,300 outstanding shares of its common stock, at a price of $18.83 per share, for a total of approximately $50 million.

Orbital intends to use the net proceeds from the sale of the notes, together with cash on hand, to repurchase its outstanding 9% senior notes due 2011 and has used a portion of such funds to fund the above-described share repurchase.

The notes were sold to qualified institutional buyers in accordance with Rule 144A under the Securities Act of 1933, as amended. The notes and common stock issuable upon conversion of the notes have not been registered under the Securities Act of 1933, or any state securities laws, and unless so registered, may not be offered or sold in the United States except pursuant to an exemption from the registration requirements of the Securities Act of 1933 and applicable state laws. Orbital will file a registration statement regarding resales of the notes and common stock issuable upon their conversion with the Securities and Exchange Commission within 120 days after the original issuance of the notes.

This release shall not constitute an offer to sell or the solicitation of an offer to buy any of these securities, nor shall it constitute an offer, solicitation or sale in any jurisdiction in which such offer, solicitation or sale is unlawful.

About Orbital

Orbital develops and manufactures small rockets and space systems for commercial, military and civil government customers. Orbital's primary products are satellites and launch vehicles, including low-orbit, geosynchronous-orbit and planetary spacecraft for communications, remote sensing, scientific and defense 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 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

Safe Harbor Statement

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, product performance and market acceptance of products and technologies, the outcome of the government investigation, as well as other risk factors and business considerations described in the company's SEC filings, including its annual report on Form 10-K/A, 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
Public and Investor Relations:
Barron Beneski, 703-406-5528
Beneski.barron@orbital.com