The Boeing X-37 (also known as the Orbital Test Vehicle) is an American 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 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.
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 and 2011.
U.S. Air Force Pushes For Orbital Test Vehicle by Leonard David, Senior Space Writer Date: 17 November 2006 Time: 11:43 AM ET
There’s new military life in an old NASA project–the X-37 technology demonstrator. The U.S. Air Force announced today that it is developing an Orbital Test Vehicle (OTV), based on the design of a NASA X-37 craft.
It is to be designated as the X-37B Orbital Test Vehicle.
The U.S. Air Force has decided to continue full-scale development and on-orbit testing of an unmanned long-duration, reusable space vehicle.
The new OTV effort dovetails off of industry and government investments by Air Force, NASA, and the Defense Advanced Research Projects Agency (DARPA).
The OTV effort will be led by the Air Force Rapid Capabilities Office and includes partnerships with NASA and the Air Force Research Laboratory. Boeing is the prime contractor for the OTV program–the same firm that was lead on the old NASA X-37 technology demonstrator.
According to a statement from the Secretary of the Air Force, the OTV program will focus on “risk reduction, experimentation, and operational concept development for reusable space vehicle technologies, in support of long term developmental space objectives.”
The first orbital test flight of the OTV is planned for fiscal year 2008, with a launch from Cape Canaveral Air Force Station on an Atlas V launch vehicle.
The OTV is the first vehicle since the space shuttle with the ability to return experiments to Earth for further inspection and analysis.
That maiden orbital flight of the X-37B would demonstrate and validate guidance, navigation and control systems - fault tolerant, autonomous reentry and landing hardware. Also on tap is a shakeout of lightweight high temperature structures and landing gear.
Either Vandenberg Air Force Base in California or Edwards Air Force Base–also in California–will conduct reentry and recovery activities.
When last seen under DARPA program management, the X-37 technology demonstrator–also dubbed the Approach and Landing Test Vehicle–went through a series of taxi and air tests out at the Mojave, California inland spaceport, toted by the White Knight.
White Knight is the Scaled Composites mothership used to carry the privately-built suborbital SpaceShipOne to high-altitude release.
Beyond Future X
On April 7 of this year, the robotic space plane was dropped at high altitude, touching down under autonomous control, but encountered difficulties on landing and rolled off the end of a runway at Edwards Air Force Base.
When the X-37 was under NASA’s wing in the late 1990s, it was to be the first of a planned series of flight demonstrators under the rubric of Future X.
The Boeing-built X-37 was billed at the time as an unpiloted, autonomously operated vehicle designed to conduct on-orbit operations and collect test data in the Mach 25 (reentry) region of flight.
Those early plans for the X-37 called for it to be hauled into orbit by the space shuttle or lofted atop an expendable launch vehicle where it would be deployed in Earth orbit. The vehicle would then fly through space for up to 21 days and perform a variety of experiments before reentering the atmosphere and landing on a conventional runway.
But those plans were scrapped, with NASA transferring its X-37 technology demonstration program to DARPA in late 2004.
The announcement today places the robot space vehicle under the Air Force Rapid Capabilities Office.
USAF To Launch First Spaceplane Demonstrator Aug 3, 2008 By Craig Covault
The Air Force is preparing for the Atlas V launch in December of the first U.S. robotic military spaceplane mission into orbit.
The X-37B Orbital Test Vehicle flight will mark a fundamental technology milestone for the Air Force. It will carry on winged hypersonic space vehicle technology as the space shuttle is canceled. This work is designed to propel the Air Force mission more rapidly - to where the blue sky turns to black - using a reusable hypersonic craft serviced on the ground just like an airplane.
In the future, this could lead to military spaceplane capability for the same kind of rapid access to the blackness of space that the Air Force already has to the blue sky - for the same offensive and defensive missions, including intelligence, strike and communications services to the military as a whole.
The 11,000-lb. Boeing Phantom Works vehicle is about 29 ft. long with a roughly 15-ft. wingspan; the vehicle height is 9.6 ft. Its 205-ft.-tall Atlas V 501 booster will lift off from Launch Complex 41 here on 1 million lb. thrust. The 501 version with no solid rocket motors can carry up to 10.6 tons to low Earth orbit. The orbital test vehicle will be carried under a shroud on the United Launch Alliance booster.
Once in orbit, the spacecraft will open a small payload bay and deploy a gallium arsenide solar array to power its flight. The exact mission duration is classified.
The X-37B is designed for multiple missions, moving X-plane flight testing into space from the ground.
A landing is planned at the space shuttle runway at Vandenberg AFB, Calif., according to U.S. Air Force Lt. Col. Mark W. Brown in the Office of the Secretary of Defense. Touchdown should occur after some weeks in orbit demonstrating the new computational and other technologies of the Space Maneuvering Vehicle (SMV). The shuttle runway at Edwards AFB, Calif., could be an alternate landing site.
The touchdown will involve a steep 20-deg., 170-190-kt. diving shuttle-type approach similar to that used in helicopter drop tests with a subscale X-40 vehicle and the more complex X-37A.
The X-37B is to test advanced thermal protection materials, autonomous approach and landing schemes, and orbital and ground operations.
The U.S. Air Force Space Command and the Defense Advanced Research Projects Agency will control the flight. The project was taken over by Darpa when NASA dropped its collaboration with the Air Force in 2004 after the space agency determined that it was much more a military than a joint civil/military endeavor. The NASA Marshall Space Flight Center, however, has done extensive work on the program.
The X-37B will use advanced thermal protection tiles and carbon-carbon materials to protect its carbon composite and aluminum skin during reentry. The vehicle has as a nitrogen tetroxide/hydrazine propulsion system with a robust propellant load for maneuvering in space and for the deorbit burn. A more cutting-edge Aerojet kerosene/hydrogen peroxide system developed initially for the vehicle was dropped for use on the first flight, but it could fly on later missions.
The mission will use an Atlas V Eastern Range slot that had been reserved for the launch of NASA’s Lunar Reconnaissance Orbiter and Lunar Crater Observation and Sensing Satellite. That flight is now slated for February-March 2009 (AW&ST July 28, p. 30).
Research conducted at the Air Force Institute of Technology at Wright-Patterson AFB, Ohio, shows that an operational SMV would support the Air Force Space Command Strategic Master Plan prepared in 2000. The research found that it would have “direct and substantial” effect on four of the top 10 Space Command priorities in the near term and six in the mid-term. Those priorities include:
Intelligence, surveillance and reconnaissance of ground targets with either integrated sensors or deployed surveillance satellites.
Deployment of Space Control Microsatellites for key surveillance and intelligence missions in a crisis.
Rapid replenishment of constellations by the small satellites that could be carried in an SMV payload bay.
Unclassified tests of X-40 and X-37A atmospheric flight test versions of the vehicle have been underway for years at Edwards AFB and Holloman AFB, N.M.
More recently, drops from the Scaled Composites WhiteKnightOne carrier aircraft for SpaceShipOne have been part of those evaluations.
The X-37’s shape is a 120% scale derivative of the X-40A, also designed and built by Boeing; X-40 drop tests began in 1998.
The X-40A - which lacks the X-37’s advanced thermal protection materials, rocket engine, experiment bay and other spacecraft systems - was released from a U.S. Army Chinook helicopter in a series of free-flight tests in 2001 to reduce technical risk before testing the X-37A from a CH-47. During drops, the X-37A made complex maneuvers such as pitch, roll and yaw adjustments when the nose was raised, rotated and moved side to side in flight.
It’s noteworthy that as the space shuttle is being phased out, X-37B work will continue in space using a winged reusable vehicle that, operationally, would also be equipped with a payload bay. Those attributes - wings for a gliding reentry and horizontal landing, coupled with a payload bay that can be reconfigured for diverse operations - are something that no traditional satellite can provide.
The U.S. flight comes after 50 years of USAF spaceplane research. That work goes back to the manned, winged USAF Dyna-Soar program (that never flew), but preceded even the NASA Project Mercury ballistic capsule in its design.
Neil Armstrong - who was an X-15 pilot, then astronaut commanding Apollo 11 to the first manned landing on the Moon - was selected initially as a Dyna-Soar pilot before he shifted to NASA in 1962.
Until now, the inability of the Air Force to conduct spaceplane tests in orbit, let alone field an operational vehicle, stems back to compromises with NASA over the shuttle development that began 35 years ago. The situation also involves new U.S. national space policy, which has now swung much more in favor of military space.
Ironically, a space shuttle “drop test” of the X-37B had been planned for 2006 but was canceled after the Columbia accident in 2003. The growing military capability in space, however, posed by China, India, Israel and eventually even Iran has helped to keep up momentum in new space-access and counterspace programs.
The X-37B like the shuttle uses a double delta wing, and the vehicle will use shuttle aerodynamic reentry algorithms.
Whether more than one X-37B flight takes place is yet to be determined. But later tests by it or related vehicles, as well as continued technology development, could give the Pentagon a new foothold in space for more diverse robotic military operations.
Unlike the shuttle, operational spaceplane versions would be relatively small and always flown on expendable launch vehicles or larger spaceplane carriers. A rapid access to space and low cost are two other important objectives the shuttle was never able to provide. Robotic operations, as opposed to manned flights, will be a key to lower cost.
The uniquely shaped vehicle is an innovative approach to fulfilling an Air Force need for a new generation of small and reusable, highly maneuverable space vehicles to perform a variety of tasks. It is designed for quick turnaround - 72 hr. or less between missions - and it can remain on station for up to one year.
Boeing Phantom Works developed the SMV demonstrator under the direction of the U.S. Air Force Research Laboratory?Military Spaceplane Technology program at Kirtland AFB, N.M., and the Air Vehicle Directorate at Wright-Patterson AFB, Ohio.
During 1969-88, the Soviet Union conducted five flight tests of a robotic military spaceplane prior to a single robotic flight later in 1988 of its much larger Buran shuttle intended for manned operations. Four of the Soviet “Bor” spaceplane tests, all launched by an expendable booster, were successful.
All were lifting-body wing designs except one with the double delta wing of Buran to validate its hypersonic aerodynamics.
Secretive US X-37B Space Plane Could Evolve to Carry Astronauts by Leonard David, SPACE.com's Space Insider Columnist Date: 07 October 2011 Time: 05:18 PM ET
LONG BEACH, Calif. – The maker of the X-37B robotic space plane has outlined new plans for the spacecraft and a scaled-up version to support space station cargo deliveries or even carry astronauts into orbit.
The Boeing X-37B robotic space plane – also known as the Orbital Test Vehicle or OTV – is being operated by the U.S. Air Force Rapid Capabilities Office, toting top-secret payloads into Earth orbit.
An X-37B OTV and derivatives plan was outlined here by Arthur Grantz, chief engineer, Experimental Systems Group at Boeing Space and Intelligence Systems in Seal Beach, Calif. He spoke at Space 2011, a conference organized by the American Institute of Aeronautics and Astronautics (AIAA).
Small test platform
Last year, the X-37B completed its first test mission of 244 days and demonstrated the viability of a small test platform that can return experiments for post-flight inspection and analysis, Grantz reported. “We validated all the autonomous guidance, navigation and control, aerodynamics and aero-heating and the thermal protection system,” he said.
Grantz said the maiden voyage of the unpiloted X-37B proved highly successful after its launch atop an Atlas 5 501 booster. Its landing at Vandenberg Air Force Base in California required no ground intervention during the entire orbital re-entry.
Turnaround of that first vehicle for its next flight has required less time and hours than expected supporting the concept of an affordable, reusable system. In fact, the deployable and stowable solar array used on that first flight is onboard the third X-37B mission, he said.
“From a test vehicle standpoint, the 244 days is the longest duration on orbit for a reusable spacecraft,” Grantz told the audience.
The X-37B looks much like a miniature version of NASA’s space shuttle, but is much smaller. Two X-37Bs could fit inside the 60-foot (18-meter) cargo bay of a NASA shuttle.
According to Air Force specifications, the basic X-37B design is about 29 feet (8.8 meters) long and 15 feet (4.5 meters) wide. At launch, it weighs about 11,000 pounds (4,990 kilograms).
A larger version of the space plane design, dubbed X-37C in Boeing studies, would also still fit inside a space shuttle payload bay. Boeing is studying potential unmanned and crewed versions of that larger space plane for future missions.
Space plane’s future uses
In scoping out future uses of the X-37B, Grantz said the craft could let loose a free-flying satellite loaded with experiments bound for low to medium Earth orbits, even to a geosynchronous Earth orbit. [Video: Secretive Space Plane, Meet the X-37B]
At the conclusion of the experiment, the free flyer would lower its orbit and re-circularize where the X-37B could rendezvous with it, collect the experiment portion of the free flyer and then return it to Earth for inspection and destructive analysis.
“We can also demonstrate three-dimensional mapping of near-earth Objects” for asteroid detection purposes, Grantz suggested.
With the retirement of the space shuttle orbiter fleet, Grantz noted that the X-37B represents the only vehicle flying in the world today that can provide a soft 1.5-G class return of sensitive cargo from the International Space Station. The X-37B, as currently designed, is able to support high-value payload delivery and return, he said.
For example, the vehicle can support the return of biological samples or material science crystals that are at the core of the space station’s microgravity experiments and unsupported by high acceleration capsules, Grantz reported. Time-sensitive cargo can be quickly extracted from the payload bay after an X-37B’s runway landing.
X-37C: New space plane for astronauts
No new technology is required to build an X-37B customized to the space station cargo mission, Grantz said. The next step, he said, is a larger vehicle with significant cargo return capabilities for ISS Line Replaceable Units (LRU’s) and experiments requiring a low acceleration return to Earth.
Grantz explained that a variety of scaled-up versions of the X-37B space plane have been studied as potential vehicles to carry astronauts or cargo into low-Earth orbit. The studies include looks at transport methods for pressurized and unpressurized cargo transport to and from the space station, as well as future Bigelow space habitats or other forms of space tourism in low-Earth orbit.
The preferred size of these derivatives is approximately 165 to 180 percent of the current X-37B.
The larger X-37C has been blueprinted, sized to support around five to six astronauts with provisions for one that is injured and requires a stretcher.
According to designs in Grantz’s paper for the Space 2011 conference, crew-carrying portion of a future X-37C type space vehicle would fly in a pressurized compartment that would fit into the payload bay of the spacecraft. The seats would be arranged along one side of the spacecraft to allow room for moving through the spacecraft in orbit and to provide the crew access to seats on the launch pad.
A hatch in the main body would be used to provide entry to the space plane on the ground, according to Grantz’s paper.
Launched atop an Atlas Evolved Expendable Launch Vehicle, this spacecraft would be capable of rendezvous, docking, deorbiting, re-entering, and landing autonomously. But it could also include the ability of an onboard pilot to control the craft, Grantz said.
“Once qualified for human flight, these vehicles could transport a mix of astronauts and cargo to the ISS and offer a much gentler return to a runway landing for the space tourism industry,” Grantz’s report states.
Length: 29 ft 3 in (8.9 m)
Wingspan: 14 ft 11 in (4.5 m)
Height: 9 ft 6 in (2.9 m)
Loaded weight: 11,000 lb (4,990 kg)
Powerplant: 1 x Rocketdyne AR2-3 rocket engine (hydrazine), 3,300 lbf (14.7 kN)
Power: Gallium arsenide solar cells with lithium-ion batteries
Payload Bay: 7 x 4 ft (2.1 x 1.2 m)
Orbital speed: 17,500 mph (28,200 km/h)
Orbit: Low Earth orbit
Orbital time: Up to 270 days