Orbital Sciences Corporation announced today that it is
in final preparations to launch the National Aeronautics and Space
Administration (NASA)’s Demonstration of Autonomous Rendezvous
Technology (DART) spacecraft aboard a Pegasus rocket. The mission is
scheduled to take place on Tuesday, October 26, 2004, from Vandenberg
Air Force Base, CA (VAFB) during an available seven-minute launch
window that extends from 11:15 a.m. to 11:22 a.m. (Pacific). This
operational schedule is subject to the completion of final testing and
other pre-launch activities, as well as acceptable weather conditions
in the VAFB area at the time of the launch.

About the Pegasus Launch Vehicle

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 at approximately 40,000 feet,
reduces cost, improves performance and provides customers with
unparalleled flexibility to operate from virtually anywhere on Earth
with minimal ground support requirements. Orbital has launched the
Pegasus rocket from six sites around the world, including VAFB;
Edwards Air Force Base, CA; Cape Canaveral, FL; Wallops Island, VA;
Kwajalein Atoll in the Central Pacific region; and the Spanish Canary
Islands. The DART mission will be the 36th flight of the Pegasus
rocket since its introduction in 1990. The Pegasus launch vehicle is
provided by Orbital under contract to NASA’s Kennedy Space Center, FL.

About the DART Spacecraft

Orbital designed, developed, manufactured and tested the DART
spacecraft for NASA’s Marshall Space Flight Center in Huntsville, AL.
The DART spacecraft will demonstrate key hardware and software
technologies that will allow one spacecraft to rendezvous with and
conduct close-proximity operations near another in-orbit spacecraft.
While previous U.S. space rendezvous and docking missions have been
piloted by astronauts, the unmanned DART spacecraft will have only
on-board computers and data from sensors to perform its rendezvous and
close-proximity maneuvers functions.

Along with NASA’s Marshall Center, Orbital also engineered,
manufactured and tested the advanced laser guidance sensor that the
DART spacecraft will use to carry out its final rendezvous and
close-proximity maneuvers with its target. Marshall pioneered the
basic video laser technology in the late 1990’s, which Orbital
subsequently qualified for space applications at its Technical
Services Division in Greenbelt, MD.

Future applications of the technologies that the DART mission is
demonstrating may be used in manned and unmanned missions of the U.S.
space program that require in-space assembly, servicing, docking or
other autonomous rendezvous operations. The DART spacecraft is nearly
six feet long with a diameter of about three feet and weighs about 500
pounds.

About the DART Mission

Following its launch aboard Pegasus into a targeted 475-mile polar
orbit, the DART spacecraft will locate and rendezvous with the
mission’s target satellite, the Multiple-Path Beyond-Line-of-Sight
Communications (MUBLCOM) spacecraft that has completed its mission and
is operating well beyond its design life. The MUBLCOM satellite was
also built by Orbital for the Defense Advanced Research Projects
Agency and was launched aboard a previous Pegasus mission in 1999.

Once the DART spacecraft achieves orbit and locates and rendezvous
with MUBLCOM, it will perform several close-proximity operations such
as approaching to as close as 15 feet and moving away from the
satellite on different vectors, as well as performing circumnavigation
maneuvers using data provided by its onboard sensors. The entire DART
mission will be performed without human intervention and will be
completed within 24 hours.

About Orbital

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 satellites and
launch vehicles, including geostationary and low-orbit spacecraft 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, the Pegasus space launch vehicle
and the DART spacecraft can be found at http://www.orbital.com

Notes to Editors:

  • NASA TV will cover live the Pegasus launch of the DART
    spacecraft. NASA TV is broadcast on AMC-9, transponder 9,
    C-band, located at 85 degrees West Longitude. The frequency is
    38880.0 MHz. Polarization is vertical and audio is monaural at
    6.8 MHz.
  • Orbital will link to NASA’s web-based pre-launch and live
    coverage of the DART mission from the company’s web site at
    www.orbital.com

Contact:

Orbital Sciences Corporation

Public and Investor Relations:

Barron Beneski, 703-406-5528

Beneski.barron@orbital.com