Orbital's Hyper-X Rocket Successfully Launches NASA's X-43A Hypersonic Scramjet.

Business Editors

DULLES, Va.--(BUSINESS WIRE)--March 27, 2004

Orbital Sciences Corporation (NYSE: ORB) announced today that its Hyper-X Launch Vehicle was successfully launched on Saturday, March 27 in a flight test that originated from NASA's Dryden Flight Research Center located at Edwards Air Force Base, California. The Hyper-X launch vehicle uses a modified first stage rocket motor, originally designed and flight-proven aboard Orbital's Pegasus(R) space launch vehicle, to accelerate NASA's X-43A air-breathing scramjet to seven times the speed of sound.

Unlike vehicles with conventional rocket engines, which carry oxygen onboard, the air-breathing X-43A scoops and compresses oxygen from the atmosphere using the shape of the vehicle's airframe. This type of propulsion system could potentially increase payload capacity of future launch vehicles and make high-speed passenger travel feasible since no onboard supply of oxidizer would be required.

"We are extremely pleased with the results of the Hyper-X flight," said Ron Grabe, Executive Vice President and General Manager of Orbital's Launch Systems Group. "After several years of detailed analysis, design upgrades and testing to address the factors that contributed to the failure of the program's first flight, it is all the more gratifying to have carried out this successful flight test. This flight was one of the most challenging missions Orbital has ever conducted and demonstrated our ability to take on and tackle the toughest technical challenges."

Mr. Grabe added, "Our congratulations go out to NASA and all the partners on this program who persevered to get it right. We now have our sights set on a successful third mission to provide even more critical data to NASA's research into the field of hypersonic flight and to extend the flight speed record set today to Mach 10."

On launch day, flight operations began when NASA's B-52B carrier aircraft took off and flew a predetermined flight path to a point 50 miles off the California coast. The Hyper-X vehicle was released from the B-52 at 2:00 p.m. (PST) approximately 40,000 feet over the Pacific Ocean. Following rocket motor ignition, the Hyper-X Launch Vehicle, carrying the X-43A scramjet, accelerated to a velocity of approximately Mach 7 (or seven times the speed of sound) and reached an altitude of 95,000 feet. Approximately 90 seconds after ignition, with the booster at a precise trajectory condition, the Hyper-X launch vehicle sent commands to the X-43A scramjet, which then separated from the booster.

Early flight results indicate that the X-43A stabilized, ignited its scramjet and provided flight data back to NASA engineers. Following the engine burn, the X-43A executed a number of aerodynamic maneuvers during its eight-minute coast to an ocean impact approximately 450 miles from the launch point. After separation, the spent booster impacted the ocean in a pre-determined splash area.

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.

Note to editors: High-resolution photos of the Hyper-X launch vehicle, suitable for publication, are available on Orbital's web site at: http://www.orbital.com/NewsInfo/Images/AdvancedLaunch/index.html