Boeing X - 37 The Boeing X - 37 , also known as the X - 37 Orbital Test Vehicle ( OTV ) , is an American reusable unmanned spacecraft . It is boosted into space by a rocket , then re - enters Earth ' s atmosphere and lands as a spaceplane . The X - 37 is operated by the United States Air Force for orbital spaceflight missions intended to demonstrate reusable space technologies . It is a 120 % - scaled derivative of the earlier Boeing X - 40 . The X - 37 began as a NASA project in 1999 , before being transferred to the U . S . Department of Defense in 2004 . It conducted its first flight as a drop test on 7 April 2006 , at Edwards Air Force Base , California . The spaceplane ' s first orbital mission , USA - 212 , was launched on 22 April 2010 using an Atlas V rocket . Its successful return to Earth on 3 December 2010 was the first test of the vehicle ' s heat shield and hypersonic aerodynamic handling . A second X - 37 was launched on 5 March 2011 , with the mission designation USA - 226 ; it returned to Earth on 16 June 2012 . A third X - 37 mission , USA - 240 , launched successfully on 11 December 2012 . Development . Origins . In 1999 , NASA selected Boeing Integrated Defense Systems to design and develop an orbital vehicle , built by the California branch of Boeing ' s Phantom Works . Over a four - year period , a total of $ 192 million was contributed to the project , with NASA contributing $ 109 million , the U . S . Air Force $ 16 million , and Boeing $ 67 million . In late 2002 , a new $ 301 - million contract was awarded to Boeing as part of NASA ' s Space Launch Initiative framework . The X - 37 was transferred from NASA to the Defense Advanced Research Projects Agency ( DARPA ) on 13 September 2004 . Thereafter , the program became a classified project , although it is not known whether DARPA will maintain this status indefinitely . DARPA promoted the X - 37 as part of the independent space policy that the United States Department of Defense has pursued since the 1986 " Challenger " disaster . The X - 37 was originally designed to be carried into orbit in the Space Shuttle ' s cargo bay , but underwent redesign for launch on a Delta IV or comparable rocket after it was determined that a shuttle flight would be uneconomical . The X - 37 ' s aerodynamic design was derived from the Space Shuttle , hence the X - 37 has a similar lift - to - drag ratio , and a lower cross range at higher altitudes and Mach numbers compared to DARPA ' s Hypersonic Technology Vehicle . As part of its mission goals , the X - 37 was designed to rendezvous with friendly satellites to refuel them , or to replace failed solar array s using a robotic arm . Its payload could also support Space Control ( Defensive Counter - Space , Offensive Counter - Space ) , Force Enhancement and Force Application systems . An early requirement for the spacecraft called for a delta - v of to change its orbit . Glide testing . The vehicle that was used as an atmospheric drop test glider had no propulsion system . Instead of an operational vehicle ' s payload bay doors , it had an enclosed and reinforced upper fuselage structure to allow it to be mated with a mothership . In September 2004 , DARPA announced that for its initial atmospheric drop tests the X - 37 would be launched from the Scaled Composites White Knight , a high - altitude research aircraft . On 21 June 2005 , the X - 37A completed a captive - carry flight underneath the White Knight from Mojave Spaceport in Mojave , California . Through the second half of 2005 , the X - 37A underwent structural upgrades , including the reinforcement of its nose wheel supports . Further captive - carry flight tests and the first drop test were initially expected to occur in mid - February 2006 . The X - 37 ' s public debut was scheduled for its first free flight on 10 March 2006 , but was canceled due to an Arctic storm . The next flight attempt , on 15 March 2006 , was canceled due to high winds . On 24 March 2006 , the X - 37 flew again , but a datalink failure prevented a free flight , and the vehicle returned to the ground still attached to its White Knight carrier aircraft . On 7 April 2006 , the X - 37 made its first free glide flight . During landing , the vehicle overran the runway and sustained minor damage . Following the vehicle ' s extended downtime for repairs , the program moved from Mojave to Air Force Plant 42 ( KPMD ) in Palmdale , California for the remainder of the flight test program . White Knight continued to be based at Mojave , though it was ferried to Plant 42 when test flights were scheduled . Five additional flights were performed , two of which resulted in X - 37 releases with successful landings . These two free flights occurred on 18 August 2006 and 26 September 2006 . X - 37B Orbital Test Vehicle . On 17 November 2006 , the U . S . Air Force announced that it would develop its own variant from NASA ' s X - 37A . The Air Force version was designated the X - 37B Orbital Test Vehicle ( OTV ) . The OTV program was built on earlier industry and government efforts by DARPA , NASA and the Air Force , and was led by the U . S . Air Force Rapid Capabilities Office , in partnership with NASA and the Air Force Research Laboratory . Boeing was the prime contractor for the OTV program . The X - 37B was designed to remain in orbit for up to 270 days at a time . The Secretary of the Air Force stated that the OTV program would focus on " risk reduction , experimentation , and operational concept development for reusable space vehicle technologies , in support of long - term developmental space objectives . " The X - 37B was originally scheduled for launch in the payload bay of the Space Shuttle , but following the 2003 " Columbia " disaster , it was transferred to a Delta II 7920 . The X - 37B was subsequently transferred to a shrouded configuration on the Atlas V rocket , following concerns over the unshrouded spacecraft ' s aerodynamic properties during launch . Following their missions , X - 37B spacecraft land on a runway at Vandenberg Air Force Base , California , with Edwards Air Force Base as an alternate site . In 2010 , manufacturing work began on the second X - 37B , OTV - 2 , which conducted its maiden launch in March 2011 . Design . The X - 37 Orbital Test Vehicle is a reusable robotic spaceplane . It is a 120 % - scale derivative of the Boeing X - 40 , measuring over in length , and features two angled tail fins . The X - 37 launches atop an Atlas V version 501 rocket with a Centaur second stage . The X - 37 is designed to operate in a speed range of up to Mach 25 on its reentry . Among the technologies demonstrated in the X - 37 include an improved thermal protection system , enhanced avionics , an autonomous guidance system and an advanced airframe . The spaceplane ' s thermal protection system is built upon previous generations of atmospheric reentry spacecraft , incorporating silica ceramic tiles . The X - 37 ' s avionics suite was used by Boeing to develop its CST - 100 manned spacecraft . According to NASA , the development of the X - 37 will " aid in the design and development of NASA ' s Orbital Space Plane , designed to provide a crew rescue and crew transport capability to and from the International Space Station " . The X - 37 is independently powered by one Aerojet AR2 - 3 engine using storable propellants , providing thrust of . The human - rated AR2 - 3 engine had been used on the dual - power NF - 104A astronaut training vehicle , and was given a new flight certification for use on the X - 37 with hydrogen peroxide / JP - 8 propellants . The X - 37 lands automatically upon returning from orbit , and is the second reusable spacecraft to have such a capability , after the Soviet Buran shuttle . The X - 37 is the smallest and lightest orbital spaceplane flown to date ; with a launch mass of around , it is approximately a quarter the size of the Space Shuttle orbiter . Operational history . OTV - 1 . OTV - 1 , the first X - 37B , launched on its first mission – USA - 212 – on an Atlas V rocket from Cape Canaveral Air Force Station , Florida , on 22 April 2010 at 23 : 58 GMT . The spacecraft was placed into low Earth orbit for testing . While the U . S . Air Force revealed few orbital details of the mission , amateur astronomers claimed to have identified the spacecraft in orbit and shared their findings . A worldwide network of amateur astronomers reported that , on 22 May 2010 , the spacecraft was in an inclination of 39 . 99 degrees , circling the Earth once every 90 minutes on an orbit . OTV - 1 reputedly passed over the same given spot on Earth every four days , and operated at an altitude of , which is typical for military surveillance satellites . Such an orbit is also common among civilian LEO satellites , and the spaceplane ' s altitude was the same as that of the ISS and most other manned spacecraft . The U . S . Air Force announced on 30 November 2010 that OTV - 1 would return for a landing during the 3 – 6 December timeframe . As scheduled , OTV - 1 de - orbited , reentered Earth ' s atmosphere , and landed successfully at Vandenberg AFB on 3 December 2010 , at 1 : 16 PST ( 09 : 16 UTC ) , conducting America ' s first autonomous orbital landing onto a runway ; the first spacecraft to perform such a feat was the Soviet Buran shuttle in 1988 . In all , OTV - 1 spent 224 days in space . OTV - 1 suffered a tire blowout during landing and sustained minor damage to its underside . OTV - 2 . OTV - 2 , the second X - 37B , launched on its inaugural mission , designated USA - 226 , aboard an Atlas V rocket from Cape Canaveral on 5 March 2011 . The mission was classified and described by the U . S . military as an effort to test new space technologies . On 29 November 2011 , the U . S . Air Force announced that it would extend the mission of USA - 226 beyond the 270 - day baseline design duration . In April 2012 , General William L . Shelton of the Air Force Space Command declared the ongoing mission a " spectacular success " . On 30 May 2012 , the Air Force stated that OTV - 2 would complete its mission and land at Vandenberg AFB in June 2012 . The spacecraft landed autonomously on 16 June 2012 , having spent 469 days in space . OTV - 3 . OTV - 3 , the second mission for the first X - 37B and the third X - 37B mission overall , was originally scheduled to launch on 25 October 2012 , but was postponed because of an engine issue with the Atlas V launch vehicle . The X - 37B was successfully launched from Cape Canaveral on 11 December 2012 . The classified mission is designated USA - 240 and is expected to last several months . Controversies . In 2010 , Tom Burghardt wrote for Space Daily that the X - 37B could be used as a spy satellite or to deliver weapons from space . The Pentagon has denied claims that the X - 37B ' s mission supports the development of space - based weapons . In January 2012 , allegations were made that the X - 37B was being used to spy on China ' s Tiangong - 1 space station module . Former U . S . Air Force orbital analyst Brian Weeden later refuted this claim , emphasizing that the different orbits of the two spacecraft precluded any practical surveillance fly - bys . Variants . X - 37A . The X - 37A was the initial NASA version of the spacecraft ; the X - 37A Approach and Landing Test Vehicle ( ALTV ) was used in drop glide tests in 2005 and 2006 . X - 37B . The X - 37B is a modified version of the NASA X - 37A , intended for the U . S . Air Force . It conducted orbital test missions in 2010 , 2011 and 2012 . X - 37C . In 2011 , Boeing announced plans for a scaled - up variant of the X - 37B , referring to the spacecraft as the X - 37C . The X - 37C would be between 165 % and 180 % larger than the X - 37B , allowing it to transport up to six astronauts inside a pressurized compartment housed in the cargo bay . Its proposed launch vehicle is the Atlas V Evolved Expendable Launch Vehicle . The X - 37C may compete with Boeing ' s CST - 100 commercial space capsule .