X-37 Credit - NASA

The Boeing X-37 Space Maneuver Vehicle was a subscale version of a putative USAF 21st Century spaceplane. The smaller-scale X-40 tested some technologies prior to completion of the X-37.

The X-37 Approach and Landing Test Vehicle (ALTV) was an experimental autonomous vehicle designed to demonstrate advanced space flight technologies. Drop tests of the X-37 ALTV were to be conducted at NASA's Dryden Flight Research Center, located at Edwards Air Force Base in California. The ALTV would be dropped five times from NASA's B-52H aircraft from approximately 12 km. Flight research objectives included verification of autonomous landing, demonstration of integrated vehicle and range operation through a Flight Operations Control Center (FOCC), verification of predicted stability and aerodynamic control effectiveness, and verification of ability to conduct flight operations for various wind speeds and different entry azimuths.

The forerunner of the X-37 ALTV, the X-40A, successfully completed a series of seven approach and landing tests at NASA Dryden in 2000 and 2001. About 20 percent smaller than the X-37, the X-40A was released from a helicopter at 4600 m during the series of unpowered glide flights. These flights validated the autonomous flight control system planned for the X-37, thereby reducing the risk of the X-37 program.

The vehicle was assembled at Boeing's High Desert Assembly, Integration and Test Facility in Palmdale, California. NASA's Marshall Space Flight Center in Huntsville, Ala., managed the X-37 program. NASA Dryden was responsible for the X-37 flight activities.