DULLES, Va., Feb 5, 2002 /PRNewswire-FirstCall via COMTEX/ --

- 31st Pegasus Mission Originated from Cape Canaveral, Florida -

Orbital Sciences Corporation (NYSE: ORB) announced that it successfully launched the National Aeronautics and Space Administration's (NASA's) High Energy Spectroscopic Imager (HESSI) satellite into its targeted orbit aboard the company's Pegasus(R) rocket earlier today. The scientific satellite was accurately delivered into its targeted orbit approximately 370 miles (595 kilometers) above the Earth. Today's mission, which originated from Cape Canaveral, Florida, was the 31st Pegasus flight, a depth of experience unmatched by any other commercial small launch vehicle.

At approximately 2:29 p.m. EST, the company's L-1011 Pegasus carrier aircraft took off from Cape Canaveral and followed a flight path to a predetermined launch point off the Florida coast. A short-term degradation of one of the communications links between the mission control center and the airborne launch crew required a recycle of the launch sequence, which took about 30 minutes to perform. On the second attempt, the Pegasus rocket was released at approximately 3:58 p.m. and, following a planned five-second free fall, ignited its first stage rocket motor. Approximately nine and a half minutes later, Pegasus accurately deployed the HESSI satellite into its near- circular orbit, inclined 38 degrees to the equator. Preliminary information indicates that the main operating systems of the HESSI satellite are working as planned in the early stages of its mission.

Mr. David W. Thompson, Orbital's Chairman and Chief Executive Officer, said, "This mission once again highlights the Pegasus launch system's outstanding record of reliability. We are very pleased to continue our 2002 space mission operational campaign with such a successful outcome. We wish NASA and the University of California at Berkeley team the greatest of success in their important solar imaging mission."

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. For the HESSI launch, the Florida Space Authority provided logistical and facility support for Orbital's launch team, which is primarily based in California and Virginia.

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 are spacecraft and launch vehicles, including geostationary and low-orbit satellites for communications, remote sensing and scientific missions; ground- and air-launched rockets that deliver satellites into orbit; and missile defense boosters that are used as interceptor and target 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.

                    MAKE YOUR OPINION COUNT -  Click Here
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
Copyright (C) 2002 PR Newswire.  All rights reserved.