DULLES, Va.Dec. 7, 2006--Orbital Sciences Corporation (NYSE: ORB) announced today that it priced its offering of $143.75 million aggregate principal amount of 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 closing of the notes offering is expected to occur on December 13, 2006.

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. Concurrently with the offering, the company is repurchasing 2,655,300 outstanding shares of its common stock, at a price of $18.83 per share, for a total of approximately $50 million.

Under certain circumstances, the notes will be convertible at the option of the holder into cash and, at Orbital's option, shares of common stock, at an initial conversion rate of 40.8513 shares per $1,000 principal amount of notes. The initial conversion price of approximately $24.48 represents a 30% premium to today's closing price of $18.83 per share of Orbital common stock.

The notes are convertible upon the occurrence of certain events and, in addition, on or after January 15, 2026, will be convertible at any time prior to the second business day prior to maturity. Upon conversion, the company will pay cash or a combination of cash and shares of Orbital common stock. The initial conversion rate is subject to adjustment in certain circumstances.

Orbital will have the right to redeem the notes any time on or after January 21, 2014 at the principal amount plus accrued and unpaid interest (including additional interest, if any). Noteholders will have the right to require Orbital to repurchase all or a portion of their notes for cash on January 15, 2014, January 15, 2017, and January 15, 2022, or after the occurrence of certain fundamental changes.

The notes will be 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.

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 include for example, our expectations regarding the completion of the sale of the convertible notes and the repurchase of the existing senior notes and common stock. 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.

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

    SOURCE: Orbital Sciences Corporation