NASA and Department of Defense Order Four Pegasus and Minotaur Rockets

DULLES, Va., Jan. 23 /PRNewswire-FirstCall/ -- Orbital Sciences Corporation (NYSE: ORB) recently received firm orders for four small space launch vehicles from the U.S. Government, the company announced today. At the end of 2002, the National Aeronautics and Space Administration (NASA) contracted with the company to launch its Spectroscopy and Photometry of the Intergalactic Medium's Diffuse Radiation (SPIDR) satellite aboard the company's Pegasus rocket in a mission that will take place in 2005. Separately, the U.S. Department of Defense (DoD) contracted with the company for three Minotaur space launch vehicles under the U.S. Air Force's Orbital/Suborbital (OSP)-1 program. One of the Minotaur vehicles will be used for the Department of Defense's Near-Field Infrared Experiment (NFIRE) mission and the other two vehicles will be used for missions to be announced by the DoD at a later date. Together, the four firm orders total approximately $60 million in value. The missions will be executed by Orbital beginning in 2003 and will be completed over the next several years. The company did not disclose the financial terms of the individual missions.

Mr. David W. Thompson, Orbital's Chairman and Chief Executive Officer, said, "As the world's preeminent supplier of small launch vehicles, we are very pleased with the continued strong demand for our family of small launchers and booster rockets. We are very grateful for the confidence our customers have in our launch vehicle products and believe it is well placed. Our company is totally committed to continuing our outstanding reliability record in support of our customers' important missions."

About Pegasus

Orbital's Pegasus rocket is the world's only small space launch vehicle that has been certified with NASA's Payload Risk Category 3, which the space agency reserves for its highest value space missions. With the SPIDR contract, NASA has now awarded Orbital 6 of up to 16 potential missions under Kennedy Space Center's Small Expendable Launch Vehicle Services agreement.

Pegasus is the world's leading launch system for the deployment of small satellites into low-Earth orbit. Its patented air-launch system, in which the rocket is launched from beneath Orbital's "Stargazer" L-1011 carrier aircraft over the ocean, reduces cost and provides customers with unparalleled flexibility to operate from virtually anywhere on Earth with minimal ground support requirements.

The primary objective of the NASA-sponsored SPIDR mission is to map the "cosmic web" of hot gas, which spans the universe. The SPIDR satellite is being developed by Charles Stark Draper Laboratory and is being managed by Boston University.

About Minotaur

Orbital developed the ground-launched four-stage Minotaur rocket for the U.S. Air Force's Orbital/Suborbital Program. The vehicle uses U.S. Government-supplied Minuteman II motors that have been decommissioned as a result of arms reduction treaties, with the deactivated rocket motors serving as the vehicle's first and second stages. Its third and fourth stages, as well as its guidance and control system, use technology from the company's Pegasus rocket. Orbital is under contract to the Air Force to provide OSP integrated launch vehicles and to perform launch operations to deliver small U.S. government sponsored satellites to orbit.

The NFIRE mission to be flown on a Minotaur rocket in 2004 is sponsored by the U.S. Missile Defense Agency through the Air Force Space and Missile Systems Center's Rocket Systems Launch Program. The satellite is designed to evaluate technologies for boost-phase missile defense.

Orbital's space launch vehicles and related suborbital rockets are primarily produced at the company's engineering and manufacturing facility in Chandler, Arizona and its vehicle assembly and integration facilities at Vandenberg Air Force Base, California. The launch vehicles are primarily used by commercial, civil government and military agencies to deliver small satellites into low altitude orbit above the Earth and in missile defense systems, both as threat-simulating target vehicles and as a potential interceptor booster for the U.S. Ground-Based Midcourse Defense system.

Orbital is one of the world's leading developers and manufacturers of small space systems for commercial, civil government and military customers. The company employs approximately 2,000 people at major facilities in Virginia, Maryland, Arizona and California. In addition to its launch vehicle products, Orbital is also a leading supplier of satellites, including low- orbit, geostationary and planetary spacecraft for communications, remote sensing and scientific missions. The company 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 the Orbital
Sciences Corporation, +1-703-406-5528, or Beneski.barron@orbital.com

SOURCE Orbital Sciences Corporation

-0- 01/23/2003

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