DULLES, Va., Jun 19, 2002 /PRNewswire-FirstCall via COMTEX/ --

Launch Vehicle Served as Ballistic Target for Test Of Patriot Missile Defense System

Orbital Sciences Corporation (NYSE: ORB) announced today that it successfully launched a ballistic target vehicle from Wake Island, located in the mid-Pacific Ocean, for the Missile Defense Agency (MDA) Missile Defense Targets Joint Project Office (MDTJPO). The mission supported the operational testing of the Patriot Advanced Capability-3 (PAC-3) defense interceptor system. Orbital's target launch vehicle, identified as OT-2a, lifted off at 2:00 p.m. local Wake Island time, on May 30, 2002. It flew a ballistic trajectory 1,124 kilometers down range, reached an apogee altitude of 270 kilometers and accurately delivered a simulated reentry vehicle to an intercept area northeast of the Reagan Test Site's Gellinam Island in the Marshall Islands.

Orbital's Launch Systems Group, which is responsible for the company's space and suborbital launch programs, designed, manufactured, integrated and tested the OT-2a target vehicle at the company's facility in Chandler, Arizona. The OT-2a target vehicle is a lightweight derivative of Orbital's Theater Missile Defense Critical Measurements Program-3B (TCMP-3B) launch vehicle. It consists of two modified Minuteman SR19 rocket motors integrated with two Multiple Launch Rocket System (MLRS) motors as boost-assists for the vehicle's first stage. The OT-2a vehicle development and flight test program was achieved within an accelerated schedule and included several technological enhancements to meet the demanding mission requirements. Orbital is currently under contract to conduct a launch with a similar vehicle for MDA MDTJPO's Critical Measurements Program (CMP-4) in mid-2003.

"We are extremely pleased with the performance of the OT-2a, an enhanced SR19-based launch vehicle, especially the delivery accuracy demonstrated with new guidance algorithms developed specifically for this mission," said Mr. Ronald J. Grabe, Executive Vice President and General Manager of Orbital's Launch Systems Group. "Orbital is proud to add another successful mission to our history of supporting Patriot test exercises. We look forward to providing other vehicle development and flight test services for MDA MDTJPO in the future."

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 include low-orbit, geostationary and planetary spacecraft for communications, scientific and remote sensing missions; ground- and air-launched rockets that deliver satellites into orbit; and missile defense boosters that are used as target and interceptor 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: Barron Beneski, Public and Investor Relations, of Orbital Sciences Corporation, +1-703-406-5528, or beneski.barron@orbital.com.

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SOURCE Orbital Sciences Corporation

CONTACT:          Barron Beneski, Public and Investor Relations, of Orbital
                  Sciences Corporation, +1-703-406-5528, or beneski.barron@orbital.com

URL:              http://www.orbital.com
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