DULLES, Va.May 9, 2005--Orbital Sciences Corporation (NYSE:ORB) was recently awarded a launch services contract by the U.S. Air Force involving two new small launch vehicles to serve the U.S. military's need for responsive space launch capabilities, the company stated today. Orbital has named the vehicles Raptor 1 and Raptor 2, the designs of which are based upon the flight-proven technology from Orbital's highly successful family of space launch vehicles, which have carried out nearly 50 missions over the past 15 years with a strong record of on-time and on-cost performance. Both Raptor vehicles are designed to be air-launched to provide unrivaled operational flexibility. Orbital was awarded two contracts to develop technical documentation for these vehicles as the first step toward delivery of launch services under a $100 million indefinite delivery/indefinite quantity (IDIQ) contract announced by the government last week.

The Raptor 1 is a winged, 3-stage solid rocket vehicle carried to launch altitude and released from beneath a carrier aircraft, much as Oribtal's Pegasus space booster is currently operated. The Raptor 2 is air-launched from a C-17 military cargo and transport aircraft, using a parachute-based extraction system recently demonstrated on Orbital's successful flight of the Medium Range Target (MRT) vehicle earlier this year. Both Raptor 1 and Raptor 2 vehicles will employ the most current generation of avionics equipment that have been developed by Orbital as a common modular suite across all of the company's launch vehicle product lines. Both vehicles are approximately 55 feet in overall length and weigh 50,000 pounds at liftoff, not including the satellite payload.

About Orbital

Orbital is one of the world's leading developers and manufacturers of affordable space systems for commercial, civil government and military customers. The company's primary products are satellites and launch vehicles, including geostationary and low-orbit 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
             Beneski.barron@orbital.com

    SOURCE: Orbital Sciences Corporation