DULLES, Va., Feb. 13 /PRNewswire/ -- Orbital Sciences Corporation (NYSE: ORB) announced today that critical equipment built by the company's Sensor Systems division was successfully activated aboard the International Space Station (ISS). Carried aboard Space Shuttle Flight STS-98 as part of the U.S.-built Destiny laboratory module, the Major Constituent Analyzer (MCA) sensor will monitor the air that the astronauts breathe to ensure that the on- board air revitalization system is working properly. Similar Orbital sensors have flown on the Space Shuttle, Skylab and Spacelab and are currently in use on all U.S. Navy nuclear submarines.

Developed under contract to The Boeing Company, the MCA sensor will monitor the six major atmospheric constituents: oxygen, nitrogen, carbon dioxide, hydrogen, water vapor and methane. It will automatically sample the air throughout the ISS up to 200 times per minute, providing stable, accurate and reliable atmospheric information to the astronaut crew and to engineers on Earth. The MCA sensor weighs 125 pounds and fits into a 19-inch equipment rack. It was designed and qualified to operate for over 10 years with only routine maintenance.

Orbital's MCA unit was activated today and will play a vital role in monitoring the atmosphere aboard Destiny, where astronauts will conduct scientific research. Orbital has served as a partner on the ISS industrial team for the past 12 years, and will provide in-orbit and logistics support, as well as maintenance, for at least the next decade. A second MCA unit is planned for launch to the ISS in the 2004-2005 timeframe.

Orbital has become increasingly involved in the construction and maintenance of the ISS, the largest and most complex global space project ever undertaken. Orbiting about 200 miles above the Earth's surface, the ISS will serve not only as a laboratory for research into Earth sciences, life sciences and astronomy, but also as a crucial step toward future human space exploration.

Aside from the MCA sensor, the ISS will host a state-of-the-art space robotics system built by MD Robotics, a unit of Orbital's Canadian subsidiary MacDonald Dettwiler and Associates (MDA). This system will include multiple components such as a 58-foot "arm" to handle large payloads and assist with the docking of the Space Shuttle and a two-arm robot to handle many of the servicing and assembly tasks currently performed by astronauts on space walks. Orbital has also been supporting an initiative by the National Aeronautics and Space Administration (NASA) to study the development of a crew return vehicle (CRV), or emergency "lifeboat," for astronauts manning the ISS.

About Orbital's Sensor Systems Division

Located in Pomona, California, Orbital's Sensor Systems division has over 40 years of experience in designing, developing and manufacturing sophisticated sensors and analytical instruments for space, defense and industrial applications. Major products include space instruments, atmosphere monitors, chemical and biological agent detection devices and commercial process analyzers. The next Sensor Systems product to be deployed in space will be the Total Ozone Mapping Spectrometer (TOMS) instrument, which will monitor and map the worldwide distribution of atmospheric ozone as part of NASA's QuikTOMS satellite mission, scheduled for later this year.

More information about Orbital's Sensor Systems division can be found at http://www.orbital.com/SensorSystems .

About Orbital

Orbital is one of the largest space technology and satellite services companies in the world, with 1999 total enterprise revenues (including revenues from unconsolidated affiliates) of approximately $915 million. The company, headquartered in Dulles, Virginia, employs about 4,500 people at major facilities in the United States, Canada and several overseas locations.

Orbital is one of the world's leading manufacturers of low-cost space systems, including satellites, launch vehicles, electronics and sensors, satellite ground systems and related digital infrastructure. Its Magellan subsidiary is a pioneer in satellite-based navigation and communications products for consumer and industrial markets. Through its ORBCOMM and ORBIMAGE affiliates and ORBNAV subsidiary, Orbital is also a major operator of satellite-based networks that provide data communications, high-resolution imagery and automotive information services to customers all around the world.

More information about Orbital can be found at http://www.orbital.com . SOURCE Orbital Sciences Corporation

CONTACT: Barron Beneski, 703-406-5000, or beneski.barron@orbital.com, or Investors: Timothy Perrott, 703-406-5997, or perrott.tim@orbital.com, both of Orbital Sciences Corporation/