DULLES, Va.July 1, 2003--Orbital Sciences Corporation (NYSE:ORB) announced today that it has successfully completed its consent solicitation with respect to its outstanding 12% Second Priority Secured Notes due 2006. As of the expiration deadline for the consent solicitation, which was 5:00 p.m., New York City Time, on July 1, 2003, Orbital had received consents from the holders of 89% of the outstanding principal amount of the Notes to the proposed amendments to the indenture relating to the Notes, and the related guarantee termination and collateral release, which are described in the Company's Offer to Purchase and Consent Solicitation Statement dated June 20, 2003 (the "Offer Statement"). This consent solicitation is part of Orbital's offer to purchase the Notes described in the Offer Statement.

Orbital and the trustee under the indenture entered into various agreements to implement the amendments to the indenture, the guarantee release and the release of the collateral securing the Notes. The amendments to the indenture eliminate substantially all of the restrictive covenants contained in the indenture. The amendments, the guarantee termination and the collateral release will not become operative, however, unless and until Orbital accepts the tendered Notes for purchase pursuant to the Offer Statement.

Tendering holders who validly tendered and delivered consents prior to the Consent Date will receive 105.025% of the principal amount of the Notes validly tendered. Following the Consent Date, holders of tendered notes no longer have the right to withdraw their tender. Holders who tender their Notes after the Consent Date but on or prior to 12:00 midnight New York City time on Friday, July 18, 2003, which is the scheduled expiration date of the offer, will receive 104% of the principal amount of the Notes validly tendered. In each case, holders who validly tender their Notes shall receive accrued and unpaid interest and liquidated damages on such principal amount of Notes up to, but not including, the applicable payment date.

This press release does not constitute an offer to purchase (or a solicitation of an offer to sell) the Notes. Complete terms and conditions of the offer and consent solicitation are described in the Offer Statement, copies of which may be obtained by contacting the information agent, D.F. King & Co., Inc. at 888/567-1626.

Orbital has engaged Banc of America Securities LLC to act as exclusive dealer manager and solicitation agent in connection with the offer and consent solicitation. Questions regarding the offer and consent solicitation may be directed to Banc of America Securities, High Yield Special Products, at 888/292-0070 or 704/388-4807 (collect). Requests for documentation may be directed to the D.F. King & Co., Inc., the information agent, at 888/567-1626.

Orbital develops and manufactures small space and missile systems for commercial, civil government and military customers. The company's primary products are satellites and launch vehicles, including low-orbit, geostationary and planetary spacecraft for communications, remote sensing and scientific missions; ground- and air-launched rockets that deliver satellites into orbit; and missile defense boosters 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

    CONTACT: Orbital Sciences Corporation
             Barron Beneski, 703/406-5528

    SOURCE: Orbital Sciences Corporation