DULLES, Va.Aug. 26, 2003--Orbital Sciences Corporation (NYSE:ORB) announced today that Mr. Leo Millstein has been named Senior Vice President, General Counsel and Corporate Secretary of the Dulles, VA-based space technology company. Mr. Millstein comes to Orbital with over 20 years of combined experience in the satellite industry at INTELSAT and COMSAT. In addition, Mr. Millstein has served as a Partner at Dryer, Ellis, Joseph & Mills, a Washington, DC-based law firm and, most recently, as General Counsel of MERANT, plc, an international information technology company.

In his role at Orbital, Mr. Millstein will provide legal support to the company's executive management and the Board of Directors on major business issues, such as government contracting and regulatory compliance, corporate governance, litigation activities, SEC reporting, mergers and acquisitions and other corporate transactions. He will oversee a staff of three in-house attorneys in the company's legal department plus additional professional staff members involved in public relations, corporate communications, export control and related areas.

"On behalf of Orbital's executive team and Board of Directors, I am pleased to welcome Leo to the company. We anticipate that his exceptional background in the satellite industry and the legal profession will add a great deal of value to our corporate management efforts," said Mr. David W. Thompson, Orbital's Chairman and Chief Executive Officer.

Mr. Millstein began his career in 1975 as Corporate Counsel at COMSAT, a satellite communications company, where he handled general legal matters for 10 years. In 1985, he left COMSAT to join Washington, DC-based Dryer, Ellis, Joseph & Mills as a Partner. In 1989, Mr. Millstein returned to the satellite industry for the next 11 years, joining INTELSAT, an international satellite communications organization, as Deputy General Counsel. He later served INTELSAT as Director of Corporate Restructuring. In 2000, Mr. Millstein joined MERANT, plc as Vice President, General Counsel and Secretary, where he carried out responsibilities similar to those that he will oversee at Orbital.

Mr. Millstein holds a B.S. degree in Aeronautical and Astronautical Engineering from Purdue University and earned his law degree from George Washington University. He is married to Linda Finkelman and has a daughter.

About Orbital

Orbital develops and manufactures small space 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.

Note to Editors:

A high-resolution photograph of Mr. Leo Millstein, suitable for publication, is available on Orbital's web site at: http://www.orbital.com/Investor/ExecutiveProfiles/lmillstein.html

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

    SOURCE: Orbital Sciences Corporation