DULLES, Va.Feb. 27, 2008--Orbital Sciences Corporation (NYSE:ORB), a world leader in smaller-sized civil government and national security satellites, announced today that it has been selected by the Defense Advanced Research Projects Agency (DARPA), Arlington, VA, to develop a Phase 1 concept for System F6 (Future Fast, Flexible, Fractionated, Free-Flying Spacecraft united by Information eXchange). DARPA is the central research and development organization for the Department of Defense (DoD). It manages and directs selected basic and applied research and development projects for DoD, and pursues research and technology where risk and payoff are both very high and where success may provide dramatic advances for traditional military roles and missions. The objective of the F6 program is to demonstrate the feasibility and benefits of a satellite architecture in which traditional "monolithic" spacecraft are replaced by clusters of wirelessly-interconnected spacecraft modules.

"F6 has the potential to be a game-changing event in the history of military space systems in the same way that the internet revolutionized data communications," stated Mr. Gregg Burgess, Orbital's Vice President for National Security Systems in the Advanced Programs Group. "DARPA and Orbital have had a long and productive partnership leading to major innovations such as the Pegasus launch vehicle and numerous advanced small satellites. System F6 could transform today's military space architecture to create a truly networked system of systems in space."

About Orbital

Orbital develops and manufactures small rockets and space systems for commercial, military and civil government customers. The company's primary products are satellites and launch vehicles, including low Earth-orbit, geosynchronous Earth-orbit and planetary spacecraft for communications, remote sensing, scientific and defense missions; human-rated space systems for Earth-orbit, lunar and other 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 software-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
             Public and Investor Relations

    SOURCE: Orbital Sciences Corporation