DULLES, Va., Jul 11, 2002 /PRNewswire-FirstCall via COMTEX/ --

New Contract From Jet Propulsion Laboratory Marks Company's 15th Satellite Order in Last 18 Months

Orbital Sciences Corporation (NYSE: ORB) announced today that it has been selected for a contract, valued at approximately $39 million, by the Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology, to design, manufacture and support mission operations of a new National Aeronautics and Space Administration (NASA) atmospheric science satellite. As part of the space agency's Earth System Science Pathfinder (ESSP) small satellite program, Orbital will design, develop and build the Orbiting Carbon Observatory (OCO) spacecraft at the company's Dulles, VA satellite manufacturing facility over the next four years. NASA's ESSP missions are funded up to a total of $175 million, which includes the spacecraft, the onboard science instrument, the launch vehicle and overall mission operations. NASA's OCO mission, managed by JPL, intends to provide the first high- resolution global maps of atmospheric carbon dioxide concentrations in order to identify the natural and man-made processes that regulate this important greenhouse gas.

The OCO satellite will be based on Orbital's fully developed LEOStar spacecraft platform. The baseline plan for the OCO program calls for the satellite to be launched aboard an Orbital-supplied Taurus space launch vehicle in 2006. NASA's Kennedy Space Center is responsible for procuring the mission's launch service and will make a final selection at a later date.

Today's announcement of the OCO satellite contract continues Orbital's brisk new order rate in 2001 and 2002 for its satellite design and manufacturing business. Orbital is one of the world's leading providers of low-Earth orbit (LEO) satellites that are used in a variety of missions, including Earth and space science, remote sensing, communications and technology demonstration. The company has also firmly established itself as a first-tier supplier in the global market for higher-altitude, geosynchronous (GEO) satellites used primarily in commercial communications applications, such as television broadcasting and fixed and mobile communications.

With its selection to build the OCO spacecraft, Orbital has been awarded contracts over the past 18 months (January 2001 to July 2002) to build 15 satellites. The new satellite orders include 8 LEO science satellites, 6 GEO communications satellites (including one option order) and 1 planetary exploration spacecraft. The total value of the contracts for the 15 satellites is approximately $550 million.

The primary mission of the OCO satellite is to provide environmental researchers with the answer to the question of where human-generated carbon dioxide is absorbed from the atmosphere by natural processes. Carbon dioxide is produced whenever fuel, such as oil, natural gas and coal, is burned and is one of the principal factors in global climate change.

The OCO satellite will carry an instrument that measures the intensity of reflected sunlight from the Earth's surface. The intensity level changes with the amount of carbon dioxide in the atmosphere. By making global measurements of atmospheric carbon dioxide, scientists will be able to locate where it is being removed from the atmosphere. These high-precision measurements have been identified as critical data by the world's scientific community and will be used by researchers from NASA, the U.S. National Oceanic and Atmospheric Administration (NOAA) and numerous U.S. and international universities.

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, geosynchronous 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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