Company’s Ground-Launched Rocket to Deliver ORBIMAGE’s OrbView-4 Satellite And NASA’s QuikTOMS Ozone Monitoring Spacecraft to Orbit — Orbital’s Space Technology Capabilities Showcased in a Mission That Includes Two Company-Built Satellites, the TOMS Space Sensor and the Taurus Launch Vehicle

Orbital Sciences Corporation
announced today that it is in final preparations to launch its
Taurus® rocket, which will carry two satellites and another small commercial
payload into orbit, on Friday, September 21, 2001.
The available launch
window extends from 11:49 a.m. to 12:07 p.m. (Pacific time), with a targeted
launch time of 11:50 p.m.
This schedule is subject to final preparations and
testing, as well as acceptable weather conditions at the Vandenberg Air Force
Base, California, launch site at the time of the mission.

Onboard Orbital’s four-stage ground-launch rocket will be the OrbView-4
high-resolution and hyperspectral imaging satellite that Orbital built for
Orbital Imaging Corporation (ORBIMAGE).
Also onboard will be Total Ozone
Mapping Spectrometer spacecraft, known as QuikTOMS, which Orbital developed
for NASA’s Goddard Space Flight Center and for which the company built the
ozone mapping instrument.
In addition, the Taurus rocket will carry a small
payload for Celestis, Inc., which will not separate from the rocket’s final
stage once it reaches orbit.

On launch day, the Taurus rocket will be prepared for its mission during a
four-hour countdown procedure.
Following a final launch decision, the vehicle
will ignite its first stage rocket motor, lift off and follow a pre-programmed
launch sequence controlled by its onboard flight computer.
Approximately 11
and a half minutes after liftoff, Taurus will deliver the OrbView-4 spacecraft
into a Sun-synchronous orbit approximately 470 kilometers above the Earth.
About two and a half minutes later, Taurus will also deploy the QuikTOMS
satellite into a Sun synchronous orbit at 470 kilometers above the Earth.
Over the next month, the QuikTOMS satellite’s onboard propulsion system will
boost the spacecraft into its final 800-kilometer orbit.

About the Taurus Launch System:

Orbital developed the ground-launched Taurus vehicle to provide a cost-
effective, reliable means of launching satellites weighing up to 3,000 pounds
into low-Earth orbit.
Taurus incorporates advanced structural and avionics
technology proven on Pegasus and other operational launch systems.
It is also
designed for easy transportability, offering customers rapid-response launches
from a wide range of locations.
Since its debut in 1994, the Taurus rocket
has carried out five space missions, all of which have been successful.
most recent Taurus mission occurred in April 2000, when the rocket launched
the U.S. Department of Energy’s Multispectral Thermal Imager (MTI) satellite.

About the OrbView-4 Satellite

The Orbview-4 satellite that Orbital developed and built for ORBIMAGE will
be one of the world’s first commercial satellite to provide high-resolution
imagery from space.
OrbView-4’s digital electro-optical camera will acquire
one-meter resolution panchromatic (black and white) and four-meter resolution
multispectral (color) imagery.
In addition, OrbView-4 will be the world’s
first commercial satellite to deliver hyperspectral imagery for commercial
applications, such as classifying material types on the Earth’s surface, a
capability that will be beneficial in agricultural management, mineral
exploration and environmental monitoring.
More information about the OrbView-
4 satellite and high-resolution and hyperspectral imagery can be found at: .

About the QuikTOMS Satellite

The QuikTOMS satellite, which Orbital built for NASA’s Goddard Space
Flight Center, is based on the company’s flight-proven MicroStar spacecraft,
on which nearly 40 in-orbit satellites have been based over the last six
Originally developed for the ORBCOMM data communications network, the
MicroStar design has been readily adapted to missions for NASA, DARPA and
several commercial and international customers.
The MicroStar platform has
provided cost and schedule benefits to the QuikTOMS program through the use of
mature designs, automated manufacturing and test equipment, dedicated and
experienced personnel, and established vendors.
More information about the
QuikTOMS program can be found at: .

About the TOMS Sensor

Orbital’s Sensor Systems Division has built four of the five Total Ozone
Monitoring System (TOMS) sensors flown by NASA, including the one that will
operate aboard the QuikTOMS satellite.
Flown on U.S., Russian and Japanese
satellites beginning in the early 1980’s, these instruments have enabled the
international scientific community to better understand the Earth’s ozone
layer and the factors that alter atmospheric ozone distribution. The previous
Orbital-built TOMS sensor, launched aboard a NASA Earth Probe satellite in
1996, operated well beyond its expected in-orbit lifetime, providing the
world’s most widely used data on the Earth’s ozone layer.

In addition, the sensor gathered information on other important
atmospheric conditions, including aerosol particles from desert dust storms,
forest fires and biomass burning, UV-B radiation, and Earth surface and cloud

About Orbital

Orbital develops and manufactures affordable space systems, including
satellites, launch vehicles, sensors and electronics, and advanced 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: .

CONTACT: Barron Beneski, Public Relations of Orbital Sciences Corporation,
+1-703-406-5528, or