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X-38 Technology
The X-38 design uses a lifting body concept originally developed by the
U.S. Air Force's X-24A project in the mid-1960s. Following the jettison of
a deorbit engine module, the X-38 will glide from orbit unpowered like the
Space Shuttle and then use a steerable, parafoil parachute, a technology
recently developed by the Army, for its final descent to landing. Its
landing gear consists of skids rather than wheels.
Just because it is off-the-shelf technology doesn't mean it is old
technology. Many of the technologies we are using have never before been
applied to a human spacecraft. The X-38 flight computer is commercial
equipment that is already in use in aircraft, and the flight software
operating system is a commercial system already in use in many aerospace
applications. The video equipment being used on the atmospheric test
vehicles is existing equipment, some of which has already flown on the
Space Shuttle for other NASA experiments. The electro-mechanical actuators
that are used on the X-38 come from a previous joint NASA, Air Force and
Navy research and development project. A special coating that had already
been developed by NASA is planned for use on the X-38 thermal tiles to make
them much more durable than the tiles used on the Space Shuttle. The X-38's
primary navigational equipment, the Inertial Navigation System/Global
Positioning System, is a unit already in use on military aircraft.
Utility
Although the design could one day be modified for other uses such as a
crew transport vehicle, the X-38 would strictly be used as a CRV in its
current design. It is baselined with only enough life support supplies to
last about nine hours flying free of the space station in orbit. The
spacecraft's landing will be totally automated, although the crew will have
the capability to switch to backup systems, control the orientation in
orbit, pick a deorbit site, and steer the parafoil, if necessary. The X-38
has a nitrogen gas-fueled attitude control system and uses a bank of
batteries for power. The CRV spacecraft will be 30 feet long, 14.5 feet
wide and weigh a little over 20,000 pounds.
Beginnings
A small, in-house development study of the X-38 concept first began at
JSC in early 1995, and, in the summer of 1995, early flight tests were
conducted of the parafoil concept, dropping platforms with a parafoil from
an aircraft at the Army's Yuma Proving Ground, Yuma, Arizona. In early
1996, a contract was awarded to Scaled Composites, Inc., of Mojave, Calif.,
for the construction of three full-scale atmospheric test airframes. The
first vehicle airframe was delivered to JSC in September 1996, where it was
outfitted with avionics, computer systems and other hardware in preparation
for flight tests at Dryden. The second vehicle was delivered to JSC in
December 1996.
Further testing will include an unpiloted space flight test in late
2000, and the new century could see the CRV attached to the International
Space Station. It is estimated that the total projected cost of the X-38's
development through the completion of two space test vehicles could be less
than $80 million. About 100 people are currently working on the project at
Dryden Flight Research Center and Johnson Space Center.
Current Status
The first X-38, known as Vehicle 131, arrived at Dryden on June 4, 1997,
aboard an Air Force C-17 transport aircraft and made its maiden flight in
March of 1998. The second aircraft, V132, was delivered to Dryden in
September, 1998 and should fly in February, 1999. V132 contains the full
lifting body flight control system that allows the vehicle to fly
autonomously prior to parafoil deployment. The space flight vehicle, V201,
is nearing structural completion at JSC in Houston. Meanwhile, the
parafoils are undergoing continuous improvement tests at Yuma Proving
Grounds.
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Last Modified: February 13, 2001
Responsible NASA Official: Jenny Baer-Riedhart
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