The NASA X-38 Crew Return Vehicle

The X-38 was a technology demonstration vehicle project of the Johnson Space Center and Dryden Flight Research Center. The X-38 was a prototype for a crew return vehicle (CRV) that would be attached to the International Space Station. The CRV would provide a means of returning to Earth if an emergency requiring immediate evacuation of the Space Station arises, if an astronaut has a medical emergency requiring immediate treatment on Earth, or if the Space Shuttle fleet is grounded and the astronauts must return to Earth.

Plans for a CRV had been under consideration since the Space Station was first proposed. Proposals for CRVs have taken on many different forms. In the late 1990s NASA and ESA were working together on a concept to satisfy their Space Station crew transport needs. Rather than focusing solely on an emergency return vehicle, ESA wanted to develop a vehicle capable of both launching and returning crew members to and from the station.

CRV development was expected to cost almost $1 billion. Multinational participation remained strong in 1998 as the French company Dassault provided critical design support, and Dutch, German, and Spanish companies produced key components. In 1999, however, ESA declined to allocate funding directly for the CRV program, and instead offered ESA governments the chance to contribute individually.

The X-38 employs a lifting body design based on a 1970s-vintage X-aircraft. Rather than landing in an unassisted glide like the Space Shuttle, the X-38 will deploy a steerable parafoil that will allow the vehicle to maneuver to a landing site. The parafoil is as large as the wing area of a Boeing 747 aircraft.

Four X-38 vehicles were planned, including three atmospheric prototypes and one orbital test vehicle. Two X-38 atmospheric prototypes (Vehicle 131 and Vehicle 132) have been constructed by Scaled Composites, with parafoils supplied by Pioneer Aerospace. Avionics and control systems were incorporated into the test vehicles, and the orbital test vehicle (Vehicle 201) is currently being constructed at the Johnson Space Center.

ESA and NASA agreed to develop a design that is compatible for launch atop an ELV such as Ariane 5. This decision required that the designs of the third prototype and the orbital test vehicle be modified to be able to withstand the structural pressures of launch. While the CRV design had no space maneuvering propulsion system, an orbital transfer vehicle could be used to move it into position at the Space Station, allowing it to carry crews both to and from the Station.

Vehicle 131 conducted free-flight tests on March 12, 1998 and February 6, 1999, during which the vehicle was dropped from the wing of a B-52 and returned to the ground using its parafoil. Following the completion of its testing, the vehicle was returned to Scaled Composites to be retrofitted to the redesigned aerodynamic shape. Vehicle 132 conducted free-flight tests in March and July 1999. The third prototype is intended to become the primary atmospheric test vehicle after the turn of the century. The orbital test vehicle is scheduled for launch on the Space Shuttle in 2001.

Two airframes were manufactured. They have flown a total of 15 flights between 1997-2001. This Advanced Technology Demonstrator for a Crew Return Vehicle from the International Space Station completed four captive flights beneath B-52 0008 during 1997, three in 1998, and then performed its first drop test on March 12, 1998, using a steerable, parafoil parachute. During 1999, the X-38 had successful free flights on Feb. 6, Mar. 5, July 9 with two separate vehicles, one with and one without flight control surfaces. A captive-carry flight of Vehicle 132 attached to the B-52 mothership took place on Sept. 13, with most flight objectives reached, followed by another captive-carry flight on Nov. 18. Employing a lifting-body concept, the X-38 is expected to be developed for a fraction of the costs of previous human space vehicles.

The X-38
Type	Crew Return Vehicle
Manufacturer	Scaled Composites (prototypes)
Maiden flight	1999
Status	Cancelled 29 April 2002
Primary user	NASA
Number built	2 atmospheric vehicles 1 orbital vehicle (incomplete)
Developed from	The Martin-Marietta X-24

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The X-38 research vehicle drops away from NASA's B-52 mothership immediately after being released from the wing pylon

The X-38 Crew Return Vehicle (CRV) was a prototype for a wingless lifting body reentry vehicle that was to be used as a Crew Return Vehicle for the International Space Station (ISS). The X-38 was developed to the point of a drop test vehicle before its development was cancelled in 2002 due to budget cuts. ^[1]

History

The crew size for the ISS depends upon the crew return capability: the crew is limited to three because the Russian Soyuz TMA vehicle that will remain docked to the ISS can only hold three people. Since it is imperative that the crew members be able to return to Earth if there is a medical emergency or if other complications arise, a Crew Return Vehicle able to hold up to seven crew members was planned from the outset: this would have allowed the full complement of seven astronauts to live and work onboard the ISS. NASA has designed several crew return vehicles over the years with varying levels of detail.^[2]

Development

X-38 was the program under leadership of NASA Johnson Space Center to build a series of incremental flight demonstrators for the proposed Crew Return Vehicle. In an unusual move for an X-plane, the program involved the European Space Agency and the German Space Agency DLR. It was originally called X-35. The program manager was John Muratore, while the Flight Test Engineer was future NASA astronaut Michael E. Fossum.

The X-38 design used a wingless lifting body concept originally developed by the U.S. Air Force in the mid-1960s during the X-24A program, and it was Muratore's brainchild.

The X-38 program used unmanned mockups to test the CRV design. The flight models were:

X-38 V-131
X-38 V-132
X-38 V-131R, which was the V-131 prototype reworked with a modified shell
X-38 V-201, which was an orbital prototype to be launched by the Space Shuttle
X-38 V-133 and V-202 were also foreseen at some point in the project but were never built.

The X-38 V-131 and V-132 shared the aerodynamic shape of the X-24A. This shape had to be enlarged for the Crew Return Vehicle needs (crew of seven astronauts) and redesigned, especially in the rear part, which became thicker.

The X-38 V-131R was designed at 80 percent of the size of a CRV, and featured the final redesigned shape (Two later versions, V-133 and V-201, were planned at 100 percent of the CRV size). The X-38 V-201 orbital prototype was 80 percent complete, but never flown.

In tests the V-131, V-132 and V-131R were dropped by a B-52 from altitudes of up to 45,000 ft (13,700 m), gliding at near transonic speeds before deploying a drogue parachute to slow them to 60 mph (95 km/h). The later prototypes had their descent continue under a 7,500 ft² (700 m²) parafoil wing, the largest ever made. Flight control was mostly autonomous, backed up by a ground-based pilot.

The X-38 project cancellation was announced on April 29, 2002 ^[1] due to budget concerns.

The Design

Following the jettison of a deorbit engine, the X-38 would have glided from orbit and used a steerable parafoil for its final descent and landing. The high speeds at which lifting body aircraft operate make them dangerous to land. The parafoil would have been used to slow the vehicle and make landing safer. The landing gear consisted of skids rather than wheels: the skids worked like sleds so the vehicle would have slid to a stop on the ground.

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X-38 V-201 test model located at Bldg. 220 at Johnson Space Center, Houston, Texas

Both the shape and size of the X-38 were different from that of the Space Shuttle. The Crew Return Vehicle would have fit into the payload bay of the shuttle. This does not, however, mean that it would have been small. The X-38 weighed 10,660 kg and was 9.1 meters long. The battery system, lasting nine hours, was to be used for power and life support. If the Crew Return Vehicle was needed, it would only take two to three hours for it to reach Earth.

The parafoil parachute, employed for landing, was derived from technology developed by the U.S. Army. This massive parafoil deploys in stages for optimum performance. A drag chute would have been released from the rear of the X-38. This drag chute would have been used to stabilize and slow the vehicle down. The giant parafoil — area of 687 square meters — was then released. It would open in four stages (a process called staging). While the staging process only takes 45 seconds, it is important for a successful chute deployment. Staging prevents high-speed winds from tearing the parafoil.

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The spacecraft’s landing was to be completely automated. Mission Control would have sent coordinates to the onboard computer system. This system would also have used wind sensors and the Global Positioning System (a satellite-based coordinate system) to coordinate a safe trip home. Since the Crew Return Vehicle was designed with medical emergencies in mind, it made sense that the vehicle could find its way home automatically in the event that crew members were incapacitated or injured. If there was a need, the crew would have the capability to operate the vehicle by switching to the backup systems. In addition, seven high altitude low opening (HALO) parachute packs were included in the crew cabin, a measure designed to provide for the need to jettison the craft.

An Advanced Docking Berthing System (ADBS) was designed for the X-38 and the work on it led to the Low Impact Docking System the Johnson Space Center later created for the planned vehicles in Project Constellation.

References

X-38 (English). Federation of American Scientists. Retrieved on 2006-09-20.

Marcus Lindroos. NASA ACRV (English). Encyclopedia Astronautica. Retrieved on 2007-01-05.

NASA Dryden Fact Sheets. NASA. Retrieved on 2006-09-13.

NASA - Current Research Projects - X-38 CRV. NASA. Retrieved on 2006-09-13.

X38/CRV FDIR. NASA's Smart Systems Research Lab. Retrieved on 2006-09-13.

Crew Return Vehicle (CRV). ESA. Retrieved on 2006-09-14.

Wikipedia

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.

Engineers at NASA's Dryden Flight Research Center, Edwards, Calif., and the Johnson Space Center, (JSC) Houston, Texas, were flight-testing the X-38, a prototype spacecraft that could have become the first new human spacecraft built in the past two decades that travels to and from orbit. The vehicle was being developed at a fraction of the cost of past human space vehicles. The goal was to take advantage of available equipment, and already developed technology for as much as 80 percent of the spacecraft's design.

Using available technology and off-the-shelf equipment significantly reduces cost. The original estimates to build a capsule-type crew return vehicle (CRV) were more than $2 billion in total development cost. According to NASA project officials, the X-38 concept and four operational vehicles will to be built for approximately one quarter of the original $2 billion cost.

Full-scale, unpiloted "captive carry" flight tests began at Dryden in July 1997 in which the vehicle remained attached to the NASA B-52 aircraft. Unpiloted free-flight drop tests from the B-52 began in March 1998.

The immediate goal of the innovative X-38 project, was to develop the technology for a prototype emergency CRV, or lifeboat, for the ISS. The project also intended to develop a crew return vehicle design that could be modified for other uses, such as a possible joint U.S. and international human spacecraft that could be launched on the French Ariane 5 booster.

In the early years of the International Space Station, a Russian Soyuz spacecraft was be attached to the station as a CRV. But, as the size of the crew aboard the station increases, a return vehicle that can accommodate up to six passengers would be needed. The X-38 design used a lifting body concept originally developed by the Air Force's X-24A project in the mid-1970's. After the deorbit engine module is jettisoned, the X-38 would 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 would consist of skids rather than wheels.

Off-the-shelf technology doesn't mean it is old technology. Many of the technologies used in the X-38 had never before been applied to a human spacecraft.

The X-38 flight computer is commercial equipment that is currently used in aircraft, and the flight software operating system is a commercial system already in use in many aerospace applications. The video equipment on the atmospheric vehicles is existing equipment, some of which has already flown on the Space Shuttle for other NASA experiments. The electromechanical actuators that are used on the X-38 come from a previous joint NASA, Air Force, and Navy research and development project.

An existing special coating developed by NASA was to be used on the X-38 thermal tiles to make them 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 Navy fighters.

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. It was baselined with only enough life support supplies to last about nine hours flying free of the space station in orbit. The spacecraft's landing would be totally automated, although the crew would be able to switch to backup systems, control the orientation in orbit, pick a deorbit site, and steer the parafoil, if necessary. The X-38 CRV had a nitrogen gas-fueled attitude control system and used a bank of batteries for power. The spacecraft was to be 28.5 feet long, 14.5 feet wide, and weigh about 16,000 pounds.

An, in-house development study of the X-38 concept began at JSC in early 1995. In the summer of 1995, early flight tests were conducted of the parafoil concept by 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. to build 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 the flight tests at Dryden. A second vehicle was delivered to JSC in December 1996.

Some 200 people were working on the project at Johnson, Dryden, and the Langley Research Center in Hampton, Va. This was the first time a prototype vehicle has been built-up in-house at JSC, rather than by a contractor; an approach that has many advantages. By building up the vehicles in-house, engineers had a better understanding of the problems contractors experience when they build vehicles for NASA. JSC's X-38 team will have a detailed set of requirements for the contractor to use to construct the CRVs for the ISS. This type of hands-on work was done by the National Advisory Committee on Aeronautics (NACA), NASA's predecessor, before the space age began. Dryden conducted model flights in 1995. The 1/6 scale-model of the CRV spacecraft using a parafoil parachute system was flown 13 times. The results showed that the vehicle had good flight control characteristics and also demonstrated good slideout characteristics

The X-38 project is a series of five prototype research vehicles developing technology to build and operate a space station crew return vehicle (CRV). The wingless CRV, when operational, would be the first reusable human spacecraft to be built in more than two decades.

Three X-38s are serving as testbeds in the development program and NASA Dryden Flight Research Center, Edwards, Calif., is the site of the program's atmospheric flight-testing. A fourth vehicle will be space-rated and used to evaluate the CRV design when it is released from an orbiting space shuttle to return to Earth.

The design of the X-38 incorporates the wingless lifting body concept pioneered at Dryden. Six unique lifting body configurations were tested at Dryden between 1963 and 1975. Data from the aerodynamic studies contributed to the design and operational profile of the space shuttles and is reemerging to help develop the CRV.

When operational, the CRV will be an emergency vehicle to return up to seven International Space Station (ISS) crewmembers to Earth. It will be carried to the space station in the cargo bay of a space shuttle and attached to a docking port. If an emergency arose that forced the ISS crew to leave the space station, the CRV would be undocked and - after a deorbit engine burn - the vehicle would return to Earth much like a space shuttle. The vehicle's life support system will have a duration of about seven hours. A steerable parafoil parachute would be deployed at an altitude of about 40,000 feet to carry it through the final descent and the landing. The CRV is being designed to fly automatically from orbit to landing using onboard navigation and flight control systems. Backup systems will allow the crew to pick a landing site and steer the parafoil to a landing, if necessary.

NASA's Johnson Space Center, Houston, Texas, manages the X-38 program and works with personnel from Dryden Flight Research Center, and Langley Research Center, Hampton, Va.

The X-38 design closely resembles the X-24A lifting body flown at Dryden from April 1969 to 1971. Wingless lifting bodies generate aerodynamic lift - essential to flight in the atmosphere - from the shape of their bodies.

The 28 research missions flown by the X-24A helped demonstrate that hypersonic vehicles like the space shuttle returning from orbital flight could be landed on conventional runways without power. The X-24A was modified in 1970 and designated the X-24B in 1971, the last lifting body configuration was tested in the 12-year research program at Dryden.

The three prototype X-38s used in the atmospheric flight testing program are 24.5 feet long, 11.6 feet wide, and 8.4 feet high, approximately 80 percent of the planned size of the CRV. The prototypes are designated V131, V132, and V131R. The V131 prototype was modified for additional testing beginning in the summer of 2000 and now carries the designation V131R. A fourth prototype, V133, will incorporate the exact shape and size of the planned CRV.

The atmospheric test vehicles, built by Scaled Composites, Mojave, Calif., are shells made of composite materials such as fiberglass and graphite epoxy, and strengthened with steel and aluminum at stress points. Vehicle weights range from 15,000 pounds to about 25,000 pounds. They land on skids - reminiscent of the famed X-15 research aircraft - instead of wheels.

The fourth X-38 in the program will be V201, the space-rated vehicle that will be flown back to Earth from an orbiting space shuttle. NASA is constructing it at the Johnson Space Center. Its inner compartment, representing the crew area, will be a pressurized aluminum chamber. A composite fuselage structure will enclose the chamber and the exterior surfaces will be covered with a Thermal Protection System (TPS) to withstand the heat generated by air friction as the vehicle returns to Earth through the atmosphere. The TPS will be similar to materials used on the space shuttles, but much more durable - carbon and metallic-silica tiles for the hottest regions, and flexible blanket-like material for areas receiving less heat during atmospheric reentry.

Much of the technology being used in the X-38 is off-the-shelf, but that doesn't mean it is old or out-dated.

The flight control computer and the flight software operating system are commercially developed and used in many aerospace applications. The space-flight X-38 prototypes will have newly designed actuators.

The current electro-mechanical actuators that move the vehicle's flight control surfaces for pitch, yaw, and roll control have been used on earlier NASA, Air Force, and Navy aeronautical research projects.

Inertial navigation and global positioning systems, similar to units used on aircraft throughout the world, will be linked to the vehicle's flight control system to automatically steer the vehicles along the correct reentry path during atmospheric tests and during the space flight test.

Using global positioning already programmed into the navigation system, the flight control computer becomes the autopilot that flies the vehicle to a predetermined landing site.

The U.S. Army originally developed the design of the parafoil that deploys in the atmosphere and carries the X-38 to Earth. The shroud lines of the steerable parachute are attached to risers linked to actuators controlled by the flight control system. The flight control system receives inputs from the inertial navigation and global positioning units to determine where the vehicle is and steers the parachute until it gets to its destination. During the descending flight, the direction and speed of any winds are calculated by the flight control system and steerage corrections are automatically made. The parafoil guidance system also predicts wind direction across the landing zone and automatically turns the vehicle up wind for a safe landing.

During atmospheric tests at Dryden, the X-38s are dropped from the wing pylon of NASA's B-52 launch aircraft at altitudes ranging from 25,000 feet to 45,000 feet. The higher altitudes give engineers more time to study vehicle aerodynamics and handling qualities during its controlled, unpiloted gliding descent before the steerable parachute is deployed.

GenCorp Aerojet, Sacramento, Calif., is developing the propulsion unit that will be used during the X-38 de-orbit tests. After the X-38 is released from the shuttle cargo bay, the small aft-mounted deorbit rocket will be fired to slow the vehicle's speed to let gravity begin pulling it back to Earth. The rocket unit will be jettisoned during the descent phase. The same deorbit propulsion unit will more than likely be used on CRVs operating with the International Space Station.

A Flush Air Data Sensing System (FADS) developed at Dryden is being used on the X-38 to collect vehicle air speed and attitude (pitch and yaw) data. This information is fed into the flight control computer to maintain the desired flight path. FADS uses tiny ports to collect the aerodynamic data instead of using conventional probes that extend into the air stream. FADS data is also monitored by test personnel on the ground during test flights.

A bank of storage batteries will provide electrical power on each of the X-38 test vehicles to operate the avionics, navigation, guidance, flight control, and parachute steering systems.

The X-38 that will be test flown from the space shuttle and the future CRV itself will use nitrogen gas attitude control systems for guidance and control during flight in space where conventional control surfaces are ineffective.

X-38 flight-testing began in March 1998 with Vehicle 131 and it will continue atmospheric testing with Vehicle 133 through 2004 or 2005.

Vehicle 131 was taken aloft by the B-52 launch aircraft for several captive-carry flights beginning in July 1997 to study its aerodynamics while attached to the aircraft's wing pylon. Two brief free flights followed, in March 1998 and February 1999, to study launch characteristics and to assess the operation of the parachute, from deployment of the small drogue through reefing of the main parafoil and landing. Data from the two flights have helped improve drogue deployment and led to landing skid improvements.

Following the two flights, Vehicle 131 was returned to Scaled Composites to be modified into the actual shape of the future CRV. The vehicle, now designated V131R, has been delivered to the Johnson Space Center where navigation, guidance, flight control, and parachute deployment systems are being installed. The modified vehicle will have the aerodynamics and atmospheric flight capabilities of the full-size CRV in the summer of 2000 when a series of up to six atmospheric test flights is scheduled to begin.

Vehicle 132, which also has the bulbous X-24A shape, carries a full flight control system, including electro-mechanical control surface actuators similar to those to be used on the CRV. V132 was test flown in March and July of 1999 with its final flight on March 30, 2000. It was the highest, fastest and longest flight to date.

The primary objectives of the flights are testing and validating the parachute deployment and steering systems, along with the vehicle's automatic flight control system.

Atmospheric test vehicle 133 is representative of the size and shape of the planned CRV. It will be used to fully test the spacecraft's integrated avionics, guidance, and flight control systems, while studying the vehicle's aerodynamics, handling qualities, and the reliability of the parachute and its steering system.

The connection between Dryden and the X-38 prototypes begins with the lifting body program of the 1960s and 70s, from which the CRV concept emerged. It now encompasses engineers involved in flight test planning and technicians working on the design and integration of vehicle systems. Dryden personnel help operate and staff mission control centers during test flights, and provide expertise in the areas of flight research, aerodynamics, and flight-control systems.

The concept of using a parafoil to autonomously recover a spacecraft from orbit and make a precision landing was successfully tested at Dryden between October 1991 and December 1996 in a project called the Spacecraft Autoland. In 1995, this concept was extended to flying a one-sixth scale X-38 using a small parafoil.

Precursors to actual X-38 flights were made to evaluate vehicle control under the parafoil using a four-foot model of the vehicle. The instrumented test article was carried into the air and dropped 13 times from a Cessna U-206 at California City, Calif., near Dryden.

One of the most prominent components of X-38 support is the B-52 launch aircraft used to take the X-38 to drop altitude. The aircraft, older than any B-52 still flying, is the same launch aircraft used in the X-15 program and was the so-called "mother ship" for all lifting bodies in that nine-year research program. The aircraft has been reconfigured to support a variety of crewed and uncrewed research vehicles that needed to be carried aloft to begin their flights back to the dry lake or conventional runways of Edwards Air Force Base.

The electro-mechanical actuators that move the flight control surfaces on the X-38s are a product of aeronautical research at Dryden. They were developed as space and weight-savers for all-electric flight control systems on new aircraft.

Dryden's involvement with the X-38s also extends to the personnel who have helped develop the flight software that will be used on V201, and its vehicle's guidance, flight control, and flight termination systems.

Pre- and post-flight vehicle inspections are conducted by a team of Dryden maintenance and engineering specialists accustomed to working with unconventional crewed and uncrewed research vehicles.

Through the entire X-38 planning and development program, Dryden engineers and technicians have served as consultants in a variety of disciplines. These include vehicle handling and flying qualities, guidance and control systems, test planning, and analyzing the flight test data.

The X-38 project began at the Johnson Space Center in early 1995 using data from past lifting-body programs and the U.S. Army's Guided Precision Delivery System tests from Yuma Proving Grounds in Yuma, Ariz. Flight tests began in Yuma using pallets dropped from an aircraft to study and develop the steerable parafoil system.

In early 1996, a contract was awarded to Scaled Composites for the construction of two atmospheric test vehicles. The first vehicle, V131, was delivered to the Johnson Space Center in September 1996, where it was outfitted with avionics, computer systems, and other hardware in preparation for its initial flight tests at Dryden. The second vehicle was delivered to JSC in December 1996.

In October 1998, Scaled Composites received an additional contract to modify V131 into V131R.

GenCorp Aerojet, Sacramento, Calif., is designing and building a de-orbit propulsion unit that will be used on V201. The base contract, valued at $16.4 million, is for one propulsion stage for the V201 flight test, with an option for a second unit. There is a second option in the contract for five operational flight units if the project is approved and the operational CRVs are built. All options would have a potential value of $71.9 million.

Total projected cost to develop and flight test the X-38s is approximately $700 million. Using available technology and off-the-shelf equipment has significantly reduced project costs, when compared to other space vehicle projects. Original estimates to build a capsule-type CRV were more than $2 billion in total development cost.

About 100 people, mostly civil servants, are currently working on the X-38 project at the Johnson, Dryden, and Langley centers. The X-38 project is the first in which a prototype space vehicle has been built-up in-house by NASA at the Johnson Space Center, rather than by a contractor. This approach has advantages. By building the vehicles in-house, NASA engineers have a better understanding of the problems contractors experience when they build vehicles for NASA.

The agency's X-38 team will have a detailed set of requirements for the contractor to use when the operational CRVs are built. This type of hands-on work dates back to the National Advisory Committee for Aeronautics (NACA), predecessor agency of NASA.

Once CRVs are operational at the International Space Station, modified follow-on versions of the vehicles could be used for brief science missions after being placed in orbit by Space Shuttles or expendable booster rockets such as the American Delta series and the French Ariane.