Orbital Sciences Corporation (NYSE: ORB)
today that it is preparing to launch the National Aeronautics and Space
Administration’s (NASA’s) X-43A “Hyper-X” research aircraft on June 2, 2001.
The X-43A will be boosted to a predetermined altitude and velocity by a
Pegasus rocket launched from NASA’s B-52 carrier aircraft off the coast of
California. The available window for the mission extends from 1:00 to 4:00
Pacific Time with a targeted launch time of 1:30 p.m. The launch schedule
subject to completion of final pre-launch testing, as well as to acceptable
weather conditions at the Edwards Air Force Base, California launch site.

The Hyper-X program is a five-year, $185 million effort to demonstrate
hypersonic propulsion and airframe technologies. While vehicles with
conventional rocket engines carry oxygen on board, the air-breathing X-43A
scramjet ingests and compresses oxygen from the atmosphere using the
uniquely shaped airframe. This type of propulsion system could potentially
increase payload capacity on future vehicles since no onboard supply of
would be required. The X-43A research vehicle was developed by NASA and
Craft Inc. of Tullahoma, Tennessee and the program is administered jointly
NASA’s Dryden and Langley Research Centers.

Orbital’s Launch Systems Group in Chandler, Arizona is building three
Pegasus-derivative rockets for the Hyper-X program. In this specialized
application, the Pegasus rocket’s second and third stages have been
as has the payload fairing, which is normally used to protect satellite
payloads. Instead of being encapsulated in a payload fairing, the X-43A
research vehicle and its adapter ride atop the front of a specially
Pegasus first-stage solid rocket motor. A newly developed thermal
system protects the Pegasus composite structures against severe heating
associated with lower-altitude hypersonic operations. Other modifications
Pegasus include upgraded first stage guidance and an avionics repackaging
permits ballasting of the booster for hypersonic flight conditions up to

On launch day, following takeoff from Edwards AFB, the B-52 carrier aircraft
will fly to a predetermined point over the Pacific Ocean on the Navy sea
and release the Hyper-X launch vehicle and X-43A research vehicle “stack.”
After a five-second free-fall, the rocket motor will ignite and quickly
accelerate the 41,400-pound stack to supersonic speeds. Approximately 90
seconds after ignition, at an altitude of approximately 95,000 feet and
speed of
Mach 7, the X-43A will separate from the launch vehicle to conduct its

The Hyper-X team has successfully achieved a number of program milestones in
short timeframe. The X-43A research vehicle and booster were first mated in
January, a comprehensive NASA Independent Review was completed in February,
a successful combined systems and taxi test was carried out in March. On
28, NASA and Orbital successfully conducted a two and a half-hour captive
flight on the B-52 aircraft. This flight verified the flutter properties of
Hyper-X stack in a representative flight environment, the Hyper-X launch
avionics and control hardware and the Hyper-X airborne support equipment.
flight also served as a complete dress rehearsal for the launch operations,
including a simulated launch at the nominal launch location and with nominal
flight conditions. Following tomorrow’s mission, two additional flight tests
planned for late 2001 and 2002.

Orbital is one of the world’s leading manufacturers of low-cost space
including satellites, launch vehicles, electronics and sensors, and
ground 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