DULLES, Va.March 25, 2005--

Mach 2.5 Target Vehicle Demonstrates 15-Foot Low Altitude Performance and High-G Maneuvers

Orbital Sciences Corporation (NYSE:ORB) announced today that it successfully flight-tested the U.S. Navy's GQM-163A "Coyote" Supersonic Sea-Skimming Target (SSST) system for the Naval Air Systems Command (NAVAIR) on March 24, 2005. The flight test was conducted at the Navy's missile test range at Point Mugu in southern California and was the fourth consecutive successful flight in a series of progressively more demanding missions that Orbital has carried out during the last year. Orbital was awarded a development contract in 2000 to meet the Navy's requirement for an affordable SSST to simulate high-speed anti-ship cruise missiles for fleet training and weapon systems research, development, test and evaluation.

Yesterday's flight test of the GQM-163A Coyote had several primary objectives, all of which were achieved. The target missile verified several vehicle performance standards, including the booster ignition, stable first-stage flight, the transition of the ducted-rocket ramjet from booster separation to started inlets, and the ducted rocket ramjet ignition and powered flight performance. The SSST was also flown along a simulated operational trajectory culminating in a descent to 15 feet above the surface of the ocean while under active control of an on-board laser altimeter, and demonstrated threshold level horizontal weave maneuvers over the full terminal maneuver distance required.

Captain Richard Walter, the U.S. Navy's Program Manager of Aerial Target and Decoy Systems, said, "Yesterday's Coyote flight was a great success. The Coyote cruised at an altitude of 50 feet and below at a speed of Mach 2.6 and sustained continuous 10g maneuvers at an altitude of 15 feet throughout the last 15 miles of flight. The Supersonic Ski-Skimming Coyote will provide a excellent testing capability of U.S. Navy ship combat systems and we look forward to providing the fleet this test capability later this year."

Mr. Keven Leith, Orbital's Vice President of Naval Programs, said, "We are pleased with the progress of the GQM-163A flight test program. This latest test flight success demonstrating the Navy's key performance parameters represents a critical step towards making the SSST system ready for operational status and limited fleet deployment in the coming months."

The GQM-163A Coyote target missile design integrates a four-inlet, solid-fuel ducted-rocket ramjet propulsion system into a compact missile airframe 18 feet long and 14 inches in diameter. Ramjet supersonic takeover speed is achieved using a decommissioned Navy MK 70 solid rocket motor for the first stage. Rail-launched from Navy test and training ranges, the highly maneuverable GQM-163A Coyote achieves cruise speeds of Mach 2.5+ following the separation of the MK 70 first-stage booster. The range of the target vehicle system is approximately 50 nautical miles at altitudes of less than 20 feet above the sea surface.

The GQM-163A Coyote program represents a significant milestone for the American aerospace industry by achieving multiple successful flights of a U.S.-built solid-fuel ducted-rocket ramjet. It is also the first successful development and flight test program of a new domestic ramjet missile configuration in over a decade. Orbital is the only U.S. Department of Defense prime contractor to be both developing and operating ramjet-powered missile systems. In addition to developing the GQM-163A Coyote, Orbital provides the Navy with launch services for the MQM-8 VANDAL SSST. The MQM-8 VANDAL is based on the liquid-fuel ramjet-powered Talos missile and provides the Navy with a legacy SSST until the more capable GQM-163A Coyote is determined to be operational for fleet use.

Orbital is developing and manufacturing the GQM-163A Coyote at its launch vehicle engineering and production facility in Chandler, Arizona. Orbital's major subcontractors include Aerojet Corporation in Gainesville, Virginia and Sacramento, California, for the solid-fuel ducted-rocket motor and CEi, Inc. in Sacramento, California, for the vehicle's avionics system.

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.

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