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.