The X-37B Space Plane - Brief History, Mission and the Future of the Program

The X-37B Space Plane - Brief History, Mission and the Future of the Program
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What is the Orbital Test Vehicle?

The X-37 or the Orbital Test Vehicle, is a robotic space plane designed and manufactured by Boeing. It is a reusable remote-controlled mini-space vehicle suitable for unmanned orbital missions. Its design was based on a previous X-40A model, although the X-37 is 120% larger.

On November 17, 2006, the U.S. Air Force developed a new version of X-37, the X-37B space plane or Orbital Test Vehicle (OTV). The new model uses a hydrazine monopropellant rocket instead of the hydrogen peroxide/JP-8 propellants of the previous model, and it is also designed for unmanned test missions.

General and Technical Characteristics of the X-37B


  • Crew: None
  • Length: 8.9 m (29 ft 3 in)
  • Wingspan: 4.5 m (14 ft 11 in)
  • Height: 2.9 m (9 ft 6 in)
  • Payload bay: 2.1 × 1.2 m (7 × 4 ft)
  • Loaded weight: 4,990 kg (11,000 lb)
  • Orbital speed: 28,200 km/h (17,500 mph)


  • Manufacturer: Boeing
  • Power supply: Gallium arsenide solar cells with lithium-ion batteries
  • Propulsion: Hydrazine monopropellant rocket
  • Protection: Advanced thermal protection systems with improved silica ceramic tiles

A Brief History

The plans for the original X-37 space plane began in 1999 by NASA and Boeing. However in 2004 the project was transferred to the Defense Advanced Research Projects Agency (DARPA) and became classified.

After several drop tests, the first mission designated as USA-212 took place on April 22, 2010. During this mission, the vehicle’s heat shield and hypersonic aerodynamic handling were tested. After 225 days in orbit, the space plane returned to the Earth on December 3, 2010 having sustained minor damage to its underside and a tire blowout during landing. The second launch (mission USA-226), took place on March 5, 2011. The space plane took off from Cape Canaveral on an Atlas 5 rocket. It was scheduled to stay into orbit for up to 270 days, however the mission was extended and the plane landed June 16, 2012.

Boeing X-37B Inside Payload Fairing Before Launch

For more details on how the X-37B was designed and developed visit the article: “USAF Plans To Launch the X-37 Spaceplane in 2010”.

The Secrecy Regarding the X-37 Mission and Speculations

The mission of the X-37B is classified. Military officials describe it as a test of new space technologies, however the operational transfer of the project from NASA to the U.S. Air Force has raised many questions.

There are several speculations regarding the objectives of the spaceplane. One of them suggests that it is a test platform for the development of space-based weapons or some kind of spy satellite, although the Pentagon has denied such claims_._ Another possible mission for the vehicle could be for rescuing astronauts, the delivery of valuable cargo to the International Space Station or the retrieval of satellites orbiting the Earth. Certain scenarios also regard the X-37 as a prototype for a future manned space plane.

Amateur astronomers keep track of the space plane’s orbit path, although they have reported that it uses its thrusters to make maneuvers, thus making it difficult to spot it again.

The Future of the Program

More launches are expected for the X-37B by the U.S. Air Force in the near future. However, there is still no timetable for these missions. A reason for this is the full schedule of commercial and military launches that will take place at Cape Canaveral in Florida throughout 2012. An alternative plan could be launching from Vandenberg Air Force Base with the use of a Delta 4 rocket.

Although a third mission is anticipated, no formal arrangements have been made yet. It is almost certain however, that the same space plane will be reused for the next OTV mission.