DULLES, Va.Sept. 10, 2004--Orbital Sciences Corporation (NYSE:ORB) today announced that it was awarded a one-year contract, worth up to $6 million, by the National Aeronautics and Space Administration (NASA) to perform a Concept Exploration and Refinement (CE&R) study for human lunar exploration systems and the development of the crew exploration vehicle. Orbital was one of several companies awarded similar contracts that are divided into six-month increments, beginning with a firm portion of approximately $3 million over the first six months and a $3 million optional portion over the second six-month period. Under these contracts from the Exploration Systems Mission Directorate, NASA is seeking outside expertise to work in partnership with the space agency. The company said that work on the contract would begin immediately.

"We are delighted to be able to continue our long-standing support of NASA's efforts to develop new human space exploration systems," said Dr. Doug Stanley, Program Manager for Orbital's Advanced Programs Group. "Ever since the Space Transportation Architecture Studies were commissioned in 1998 and throughout the Space Launch Initiative and the Orbital Space Plane Programs, Orbital has worked in partnership with NASA to develop space system concepts that are innovative, affordable and achievable. We are convinced that our team will continue to add significant value to the development of new space exploration concepts with our unique ability to offer creative solutions grounded in disciplined engineering approaches."

NASA's Vision for Space Exploration is focused on developing a sustained and affordable human and robotic space exploration program designed to explore the solar system and beyond.

About Orbital

Orbital develops and manufactures small space and rocket systems for commercial, military and civil government customers. The company's primary products are satellites and launch vehicles, including low-orbit, geosynchronous 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.

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

    SOURCE: Orbital Sciences Corporation