DULLES, Va., Jan 3, 2002 /PRNewswire via COMTEX/ --

- NASA-Sponsored Dawn Mission to Journey to Solar System's Two Largest 'Baby Planets' -

Orbital Sciences Corporation (NYSE: ORB) has been selected to develop and build the first spacecraft designed to orbit main-belt asteroids, the company announced today. The Dawn mission, selected by NASA as the next project in its Discovery program of lower-cost interplanetary probes, is scheduled for launch in 2006 on a nine- year voyage to orbit the solar system's two largest asteroids, Ceres and Vesta. By observing these "baby planets," located between Mars and Jupiter some 250 million miles (400 million kilometers) from the Sun, Dawn will improve our understanding of how planets formed to create the solar system billions of years ago. Orbital is the industry partner on the Dawn mission team, led by Dr. Christopher T. Russell of the University of California at Los Angeles and managed by NASA's Jet Propulsion Laboratory (JPL).

Under an $80 million contract to JPL, Orbital will design, manufacture, integrate and test the Dawn spacecraft and support its launch and flight operations. "Orbital is thrilled and honored to be chosen as JPL's industry partner for such an important space exploration mission," said Mr. David W. Thompson, Chairman and Chief Executive Officer. "As the company's first planetary spacecraft, Dawn is a very exciting opportunity for us to extend and apply the Earth-orbiting satellite technologies and know-how we developed and used on over 75 spacecraft in the past decade to a new type of space mission. We are looking forward to working with JPL, the world leader in interplanetary missions, to ensure that Dawn achieves its full scientific goals," he added.

The Dawn spacecraft will draw on extensive design heritage and operational experience from Orbital's LEOStar low-orbit satellites and the company's StarBus geosynchronous-orbit platforms. It also will incorporate JPL's solar- electric (ion) propulsion system and deep-space communications link. The spacecraft will weigh about 2,750 pounds (1,245 kilograms) at launch and will generate approximately 8 kilowatts of solar power at Earth's distance from the Sun. The Dawn spacecraft's core structure will measure about six feet (two meters) high, while its solar arrays will span almost 70 feet (21 meters) in length.

Dawn is scheduled for a mid-2006 launch by a Boeing Delta rocket, beginning its nine-year journey through the asteroid belt during which it will rendezvous with Vesta (in 2010) and Ceres (in 2014), orbiting from as high as 500 miles (800 kilometers) to as low as 60 miles (100 kilometers) above their surfaces.

"Ceres and Vesta are two of the largest unexplored worlds in our solar system. We'll learn about early planet formation in ways that wouldn't have been possible before this mission," said Ms. Sarah Gavit, JPL's Project Manager for the Dawn mission. She also noted that the Dawn spacecraft will employ a high-performance ion rocket engine for its primary propulsion to the asteroid belt, a new technology pioneered by JPL on NASA's Deep Space 1 mission. "I'm ecstatic that we'll have such a great opportunity to show what ion propulsion can do," she added.

Dawn's principal investigator, Dr. Russell of UCLA, will lead a government/industry team consisting of JPL, Orbital, NASA's Goddard Space Flight Center, Germany's DLR space agency, the Department of Energy's Los Alamos National Laboratory and the Institute for Space Astrophysics in Rome in carrying out the mission.

About NASA's Discovery Program

The Discovery program emphasizes lower-cost, highly-focused scientific missions. The past Discovery missions are NEAR Shoemaker, Mars Pathfinder and Lunar Prospector, all of which successfully completed their missions. Additional Discovery missions include Stardust and Genesis, which are now in space, and CONTOUR, Deep Impact and MESSENGER, scheduled for 2002, 2004 and 2004 launches, respectively.

About the Jet Propulsion Laboratory

JPL, a division of the California Institute of Technology in Pasadena, CA, manages the Dawn mission for NASA's Office of Space Science, Washington, D.C.

About Orbital

Orbital develops and manufactures affordable space systems, including satellites, launch vehicles, electronics and advanced space systems. 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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