Press Release

Orbital Set to Launch NASA Satellite Aboard Pegasus Space Launch Vehicle

By SpaceRef Editor
February 4, 2002
Filed under , ,

HESSI Mission Will Be 31st Flight of Company’s Air-Launched Rocket

Orbital Sciences Corporation
today announced that it is in final preparations to launch the
National Aeronautics and Space Administration’s (NASA) High Energy
Spectroscopic Imager (HESSI) satellite aboard the company’s Pegasus® rocket.
The launch is currently scheduled to take place on Tuesday, February 5, 2002
and will originate from Cape Canaveral, FL.

The available launch window for the HESSI mission extends from 3:21 p.m.
to 5:21 p.m. (EST), with a targeted launch time of 3:26 p.m. on Tuesday.
operational schedule is subject to the completion of final pre-launch
activities, as well as acceptable weather conditions at Cape Canaveral.

The powered flight sequence for the HESSI mission is expected to take
approximately 9 1/2 minutes, from the time the Pegasus rocket is released from
the L-1011 carrier aircraft to the time that the satellite is deployed into
Orbital plans to launch the HESSI spacecraft into a circular orbit 373
miles (600 kilometers) above the Earth, inclined at 38 degrees to the equator.

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.

The HESSI mission will be the 31st flight of the Pegasus rocket and its
first mission in 2002.
Several other Pegasus missions are currently scheduled
for 2002, including the launch of NASA’s GALEX and SORCE scientific satellites
and ORBIMAGE’s OrbView-3 high-resolution imaging satellite.

The mission of the HESSI satellite is to help researchers understand what
triggers a solar flare and how it releases energy through massive explosions
in the atmosphere of the Sun.
The HESSI spacecraft will use its imaging
instrument to produce the first high-fidelity color videos of solar flares
during the periods of their highest energy emissions.

Orbital is one of the world’s leading developers and manufacturers of
affordable space systems for commercial, civil government and military
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 .

Barron Beneski, Public and Investor Relations of Orbital
Sciences Corporation, +1-703-406-5528,

SpaceRef staff editor.