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.
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.
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.
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. 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.