Orbital’s Launch of Taurus Rocket Unsuccessful

For More Information Contact:
Barron Beneski (703) 406-5528
beneski.barron@orbital.com

(Dulles, VA 21 September 2001) – Orbital Sciences Corporation (NYSE: ORB)
announced today that the launch of its Taurus rocket, which was carrying the
OrbView-4 satellite for ORBIMAGE and the QuikTOMS satellite for NASA, did not
achieve the mission’s intended orbit. Approximately one and a half minutes
after the Taurus rocket lifted off from Vandenberg Air Force Base in California,
an in-flight anomaly was observed during the rocket’s second stage powered
flight. As a result, Orbital believes the rocket released the satellites at a
lower altitude and velocity than intended and that they did not achieve a stable
orbit.

Orbital will immediately convene and lead a failure investigation committee that
will include representatives from Orbital and ORBIMAGE to determine the cause of
today’s launch failure. NASA will also lend its expertise to the investigation.
Orbital believes that it is likely that it gathered sufficient data during the
flight that will enable the company to identify the cause of the failure.

The company stated that it carried risk insurance for the mission.

About Orbital

Orbital develops and manufactures affordable space systems, including
satellites, launch vehicles and advanced space systems. Orbital is also involved
with satellite-based networks that provide wireless data communications and
high-resolution Earth imagery to customers all around the world. More
information about Orbital can be found at: http://www.orbital.com