Space

Orbital's Launch Of Pegasus Rocket Rescheduled

(Dulles, VA 15 March 2006) - Orbital Sciences Corporation (NYSE: ORB) announced that the planned launch of its Pegasus® rocket carrying the National Aeronautics and Space Administration's (NASA's) Space Technology 5 (ST5) satellites was called off earlier today at approximately 9:35 a.m. (EST) when a locking pin in the rocket's control surface mechanism did not retract. Orbital engineers will diagnose and correct the problem and establish a new launch date at the earliest opportunity pending resolution of the issue, the availability of the range and acceptable weather conditions at the Vandenberg Air Force Base, California launch site. The company estimates that the launch delay will be no less than 48 hours.

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-orbit 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.

Contact: Barron Beneski, 7034065000, beneski.barron@orbital.com