Space Shuttle

Space Shuttle Discovery begins liftoff at the start of STS-120.
Function	Manned orbital launch and reentry
Manufacturer	United Space Alliance: Thiokol/Alliant Techsystems (SRBs) Lockheed Martin/Martin Marietta (ET) Boeing/Rockwell (orbiter)
Country of origin	United States of America
Size
Height	56.1 m (184.2 ft)
Diameter	8.7 m (28.5 ft)
Mass	2,030 t (4,470,000 lbm)
Capacity
Payload to LEO	24,400 kg (53,600 lb)
Payload to GTO	3,810 kg (8,390 lbm)
Payload to Polar orbit	12,700 kg (28,000 lb)
Payload to Landing[1]	14,400 kg (32,000 lb)[1] (Return Payload)
Launch history
Status	Retired
Launch sites	LC-39, Kennedy Space Center SLC-6, Vandenberg AFB (unused)
Total launches	135
Successes	134 successful launches 133 successful re-entries
Failures	2 (launch failure, Challenger; re-entry failure, Columbia)
First flight	April 12, 1981
Last flight	July 21, 2011
Notable payloads	Tracking and Data Relay Satellites Spacelab Great Observatories (including Hubble) Galileo, Magellan, Ulysses Mir Docking Module ISS components
Boosters (Stage 0) - Solid Rocket Boosters
No. boosters	2
Engines	1 solid
Thrust	12.5 MN each, sea level liftoff (2,800,000 lbf)
Specific impulse	269 s
Burn time	124 s
Fuel	solid
First stage - External Tank
Engines	3 SSMEs located on Orbiter
Thrust	5.45220 MN total, sea level liftoff (1,225,704 lbf)
Specific impulse	455 s
Burn time	480 s
Fuel	LOX/LH2
Second stage - Orbiter
Engines	2 OME
Thrust	53.4 kN combined total vacuum thrust (12,000 lbf)
Specific impulse	316 s
Burn time	1,250 s
Fuel	MMH / N2O4

The Space Shuttle was a partially reusable launch system and orbital spacecraft operated by the U.S. National Aeronautics and Space Administration (NASA) for human spaceflight missions. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons. The first of four orbital test flights occurred in 1981 leading to operational flights beginning in 1982. It was used on a total of 135 missions from 1981 to 2011 all launched from the Kennedy Space Center, Florida.
Major missions included launching numerous satellites, interplanetary probes, the Hubble Space Telescope (HST), conducting space science experiments, and constructing and servicing the International Space Station. Major components included the orbiters, recoverable boosters, external tanks, payloads, and supporting infrastructure. Five space-worthy orbiters were built; two were destroyed in mission accidents.
The Space Shuttle at launch consisted of the Orbiter Vehicle (OV), one external tank (ET), and two Solid Rocket Boosters (SRBs). It was launched vertically like a conventional rocket with thrust from the two SRBs and three main engines. During launch, the external tank provided fuel for the orbiter's main engines. The SRBs and ET were jettisoned before the orbiter reached orbit. At the conclusion of the orbiter's space mission, it fired its thrusters to drop out of orbit and re-enter the lower atmosphere. The orbiter decelerated in the atmosphere before flying like a glider but with reaction control system thrusters before landing on a long runway.

Overview
The Space Shuttle was a partially reuseable^[2] launch system and orbital spacecraft operated by the U.S. National Aeronautics and Space Administration (NASA) for human spaceflight missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons. The first of four orbital test flights occurred in 1981 leading to operational flights beginning in 1982, all launched from the Kennedy Space Center, Florida. The system was retired from service in 2011 after 135 missions;^[3] on July 8, 2011, with Space Shuttle Atlantis performing that 135th launch - the final launch of the three-decade Shuttle program.^[4] The program ended after Atlantis landed at the Kennedy Space Center on July 21, 2011. Major missions included launching numerous satellites and interplanetary probes,^[5] conducting space science experiments, and servicing and construction of space stations. Enterprise was a prototype orbiter used for atmospheric testing during development in the 1970s, and lacked engines and heat shield. Five space-worthy orbiters were built—two were destroyed in accidents and the others have been retired.
It was used for orbital space missions by NASA, the U.S. Department of Defense, the European Space Agency, Japan, and Germany.^[6][7] The United States funded Space Transportation System (STS) development and Shuttle operations except for Spacelab D1 and D2—sponsored by West Germany and reunified Germany respectively.^{[6][8][9][10][11]} In addition, SL-J was partially funded by Japan.^[7]
At launch, it consisted of the "stack", including a dark orange-colored external tank (ET);^[12][13] two white, slender Solid Rocket Boosters (SRBs); and the Orbiter Vehicle (OV), which contained the crew and payload. Some payloads were launched into higher orbits with either of two different booster stages developed for the STS (single-stage Payload Assist Module or two-stage Inertial Upper Stage). The Space Shuttle was stacked in the Vehicle Assembly Building and the stack mounted on a mobile launch platform held down by four explosive bolts on each SRB which are detonated at launch.^[14]
The Shuttle stack launched vertically like a conventional rocket. It lifted off under the power of its two SRBs and three main engines, which were fueled by liquid hydrogen and liquid oxygen from the external tank. The Space Shuttle had a two-stage ascent. The SRBs provided additional thrust during liftoff and first-stage flight. About two minutes after liftoff, explosive bolts were fired, releasing the SRBs, which then parachuted into the ocean, to be retrieved by ships for refurbishment and reuse. The Shuttle orbiter and external tank continued to ascend on an increasingly horizontal flight path under power from its main engines. Upon reaching 17,500 mph (7.8 km/s), necessary for low Earth orbit, the main engines were shut down. The external tank was then jettisoned to burn up in the atmosphere.^[15] After jettisoning the external tank, the orbital maneuvering system (OMS) engines were used to adjust the orbit.
The orbiter carried people and payloads such as satellites or space station parts into low Earth orbit, the Earth's upper atmosphere or thermosphere.^[16] Usually, five to seven crew members rode in the orbiter. Two crew members, the commander and pilot, were sufficient for a minimal flight, as in the first four "test" flights, STS-1 through STS-4. The typical payload capacity was about 22,700 kilograms (50,000 lb), but could be increased depending on the choice of launch configuration. The orbiter carried its payload in a large cargo bay with doors that opened along the length of its top, a feature which made the Space Shuttle unique among spacecraft. This feature made possible the deployment of large satellites such as the Hubble Space Telescope, and also the capture and return of large payloads back to Earth.
When the orbiter's space mission was complete, it fired its OMS thrusters to drop out of orbit and re-enter the lower atmosphere.^[16] During descent, the orbiter passed through different layers of the atmosphere and decelerated from hypersonic speed primarily by aerobraking. In the lower atmosphere and landing phase, it was more like a glider but with reaction control system (RCS) thrusters and fly-by wire-controlled hydraulically-actuated flight surfaces controlling its descent. It landed on a long runway as a spaceplane. The aerodynamic shape was a compromise between the demands of radically different speeds and air pressures during re-entry, hypersonic flight, and subsonic atmospheric flight. As a result, the orbiter had a relatively high sink rate at low altitudes, and it transitioned during re-entry from using RCS thrusters at very high altitudes to flight surfaces in the lower atmosphere.

Early history

Further information: Space Shuttle program and Space Shuttle design process

President Nixon (right) with NASA Administrator Fletcher in January 1972, three months before Congress approved funding for the Shuttle program

The formal design of what became the Space Shuttle began with "Phase A" contract design studies issued in the late 1960s. However, conceptualization began two decades earlier, before the Apollo program of the 1960s. One of the places the concept of a spacecraft returning from space to a horizontal landing originated was within NACA, in 1954, in the form of an aeronautics research experiment later named the X-15. The NACA proposal was submitted by Walter Dornberger.
In 1958, the X-15 concept further developed into proposal to launch an X-15 into space, and another X-series spaceplane proposal, called the X-20, which was not constructed, as well as variety of aerospace plane concepts and studies. Neil Armstrong was selected to pilot both the X-15 and the X-20. Though the X-20 was not built, another spaceplane similar to the X-20 was built several years later and delivered to NASA in January 1966 called the HL-10 ("HL" indicated "horizontal landing").
In the mid-1960s, the US Air Force conducted a series of classified studies on next-generation space transportation systems and concluded that semi-reusable designs were the cheapest choice. It proposed a development program with an immediate start on a "Class I" vehicle with expendable boosters, followed by slower development of a "Class II" semi-reusable design and perhaps a "Class III" fully reusable design later. In 1967, George Mueller held a one-day symposium at NASA headquarters to study the options. Eighty people attended and presented a wide variety of designs, including earlier Air Force designs as the Dyna-Soar (X-20).
In 1968, NASA officially began work on what was then known as the Integrated Launch and Re-entry Vehicle (ILRV). At the same time, NASA held a separate Space Shuttle Main Engine (SSME) competition. NASA offices in Houston and Huntsville jointly issued a Request for Proposal (RFP) for ILRV studies to design a spacecraft that could deliver a payload to orbit but also re-enter the atmosphere and fly back to Earth. For example, one of the responses was for a two-stage design, featuring a large booster and a small orbiter, called the DC-3, one of several Phase A Shuttle designs. After the aforementioned "Phase A" studies, B, C, and D phases progressively evaluated in-depth designs up to 1972. In the final design, the bottom stage was recoverable solid rocket boosters, and the top stage used an expendable external tank.^[17]
In 1969, President Richard Nixon decided to support proceeding with Space Shuttle development. A series of development programs and analysis refined the basic design, prior to full development and testing. In August 1973, the X-24B proved that an unpowered spaceplane could re-enter Earth's atmosphere for a horizontal landing.
Across the Atlantic, European ministers met in Belgium in 1973 to authorize Western Europe's manned orbital project and its main contribution to Space Shuttle—the Spacelab program.^[18] Spacelab would provide a multi-disciplinary orbital space laboratory and additional space equipment for the Shuttle.^[18]

Description

STS-1 on the launch pad, 1981

The Space Shuttle was the first operational orbital spacecraft designed for reuse. It carried different payloads to low Earth orbit, provided crew rotation for the International Space Station (ISS), and performed servicing missions. The orbiter could also recover satellites and other payloads from orbit and return them to Earth. Each Shuttle was designed for a projected lifespan of 100 launches or ten years of operational life, although this was later extended. The person in charge of designing the STS was Maxime Faget, who had also overseen the Mercury, Gemini, and Apollo spacecraft designs. The crucial factor in the size and shape of the Shuttle Orbiter was the requirement that it be able to accommodate the largest planned commercial and military satellites, and have the cross-range recovery range to meet the requirement for classified USAF missions for a once-around abort from a launch to a polar orbit. Factors involved in opting for solid rockets and an expendable fuel tank included the desire of the Pentagon to obtain a high-capacity payload vehicle for satellite deployment, and the desire of the Nixon administration to reduce the costs of space exploration by developing a spacecraft with reusable components.
Each Space Shuttle is a reusable launch system that is composed of three main assemblies: the reusable Orbiter Vehicle (OV), the expendable external tank (ET), and the two reusable solid rocket boosters (SRBs).^[19] Only the orbiter entered orbit shortly after the tank and boosters are jettisoned. The vehicle was launched vertically like a conventional rocket, and the orbiter glided to a horizontal landing like an airplane, after which it was refurbished for reuse. The SRBs parachuted to splashdown in the ocean where they were towed back to shore and refurbished for later Shuttle missions.

Discovery rockets into orbit, seen here just after booster rocket (SRB) separation

Five space-worthy orbiters were built: Columbia (OV-102), Challenger (OV-099), Discovery (OV-103), Atlantis (OV-104), and Endeavour (OV-105). A mock-up, Inspiration (OV-100), currently stands at the entrance to the Astronaut Hall of Fame. An additional craft, Enterprise (OV-101), was not built for orbital space flight, and was used only for testing gliding and landing. Enterprise was originally intended to be made fully space-worthy after use for the approach and landing test (ALT) program, but it was found more economical to upgrade the structural test article STA-099 into orbiter Challenger (OV-099). Challenger disintegrated 73 seconds after launch in 1986, and Endeavour was built as a replacement for Challenger from structural spare components. Columbia broke apart during re-entry in 2003. Building Space Shuttle Endeavour cost about US$1.7 billion. One Space Shuttle launch costs around $450 million.^[20]
Roger A. Pielke, Jr. has estimated that the Space Shuttle program has cost about US$170 billion (2008 dollars) through early 2008. This works out to an average cost per flight of about US$1.5 billion.^[21] However, two missions were paid for by Germany, Spacelab D1 and D2 (D for Deutschland) with a payload control center in Oberpfaffenhofen, Germany.^[22][23] D1 was the first time that control of a manned STS mission payload was not in U.S. hands.^[6]
At times, the orbiter itself was referred to as the Space Shuttle. Technically, this was a slight misnomer, as the actual "Space Transportation System" (Space Shuttle) was the combination of the orbiter, the external tank, and the two solid rocket boosters. Combined, these were referred to as the "stack"; the components were assembled in the Vehicle Assembly Building, originally built to assemble the Apollo Saturn V rocket.
Responsibility for the Shuttle components was spread among multiple NASA field centers. The Kennedy Space Center was responsible for launch, landing and turnaround operations for equatorial orbits (the only orbit profile actually used in the program), the US Air Force at the Vandenberg Air Force Base was responsible for launch, landing and turnaround operations for polar orbits (though this was never used), the Johnson Space Center served as the central point for all Shuttle operations, the Marshall Space Flight Center was responsible for the main engines, external tank, and solid rocket boosters, the John C. Stennis Space Center handled main engine testing, and the Goddard Space Flight Center managed the global tracking network.^[24]

Orbiter vehicle

Main article: Space Shuttle orbiter

Atlantis deploys the landing gear before landing on a selected runway just like a common aircraft.

The orbiter resembles a conventional aircraft, with double-delta wings swept 81° at the inner leading edge and 45° at the outer leading edge. Its vertical stabilizer's leading edge is swept back at a 50° angle. The four elevons, mounted at the trailing edge of the wings, and the rudder/speed brake, attached at the trailing edge of the stabilizer, with the body flap, controlled the orbiter during descent and landing.
The orbiter's payload bay measures 15 by 60 feet (4.6 by 18 m), comprising most of the fuselage. Information declassified in 2011 showed that the payload bay was designed specifically to accommodate the KH-9 HEXAGON spy satellite operated by the National Reconnaissance Office.^[25] Two mostly symmetrical lengthwise payload bay doors hinged on either side of the bay comprise its entire top. Payloads are generally loaded horizontally into the bay while the orbiter is oriented vertically on the launch pad and unloaded vertically in the near-weightless orbital environment by the orbiter's robotic remote manipulator arm (under astronaut control), EVA astronauts, or under the payloads' own power (as for satellites attached to a rocket "upper stage" for deployment.)
Three Space Shuttle Main Engines (SSMEs) are mounted on the orbiter's aft fuselage in a triangular pattern. The engine nozzles can swivel 10.5 degrees up and down, and 8.5 degrees from side to side during ascent to change the direction of their thrust to steer the Shuttle. The orbiter structure is made primarily from aluminum alloy, although the engine structure is made primarily from titanium alloy.
The space-capable orbiters built were OV-102 Columbia, OV-099 Challenger, OV-103 Discovery, OV-104 Atlantis, and OV-105 Endeavour.^[26]

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  Space Shuttle Atlantis transported by a Boeing 747 Shuttle Carrier Aircraft (SCA), 1998 (NASA)
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  Space Shuttle Endeavour being transported by a Boeing 747
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  An overhead view of Atlantis as it sits atop the Mobile Launcher Platform (MLP) before STS-79. Two Tail Service Masts (TSMs) to either side of the orbiter's tail provide umbilical connections for propellant loading and electrical power.
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  Water is released onto the mobile launcher platform on Launch Pad 39A at the start of a sound suppression system test in 2004. During launch, 350,000 US gallons (1,300,000 L) of water are poured onto the pad in 41 seconds.^[27]
  
  External tank
  

  Main article: Space Shuttle external tank

  The main function of the Space Shuttle external tank was to supply the liquid oxygen and hydrogen fuel to the main engines. It was also the backbone of the launch vehicle, providing attachment points for the two Solid Rocket Boosters and the Orbiter. The external tank was the only part of the Shuttle system that was not reused. Although the external tanks were always discarded, it was possible to take them into orbit and re-use them (such as for incorporation into a space station).^[15][28]
  

  [edit] Solid rocket boosters

  Main article: Space Shuttle Solid Rocket Booster

  Two solid rocket boosters (SRBs) each provided 12.5 million newtons (2.8 million lbf) of thrust at liftoff,^[29] which was 83% of the total thrust needed for liftoff. The SRBs were jettisoned two minutes after launch at a height of about 150,000 feet (46 km), and then deployed parachutes and landed in the ocean to be recovered.^[30] The SRB cases were made of steel about ½ inch (13 mm) thick.^[31] The Solid Rocket Boosters were re-used many times; the casing used in Ares I engine testing in 2009 consisted of motor cases that had been flown, collectively, on 48 Shuttle missions, including STS-1.^[32]
  

  [edit] Orbiter add-ons

  The orbiter could be used in conjunction with a variety of add-ons depending on the mission. This has included orbital laboratories (Spacelab, Spacehab), boosters for launching payloads farther into space (Inertial Upper Stage, Payload Assist Module), and other functions, such as provided by Extended Duration Orbiter, Multi-Purpose Logistics Modules, or Canadarm (RMS). An upper-stage called Transfer Orbit Stage (Orbital Science Corp. TOS-21) was also used once.^[33] Other types of systems and racks were part of the modular Spacelab system —pallets, igloo, IPS, etc., which also supported special missions such as SRTM.^[34]
  

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    MPLM Leonardo
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    IUS deploying with Galileo
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    PAM-D with satellite
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    EDO being installed
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    Spacelab in orbit
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    RMS (Canadarm)
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    Spacehab
     
    
    Spacelab
    

    Main article: Spacelab

    

    

    Spacelab LM2

    A major component of the Space Shuttle Program was Spacelab, primarily contributed by a consortium of European countries, and operated in conjunction with the United States and international partners.^[34] Supported by a modular system of pressurized modules, pallets, and systems, Spacelab missions executed on multidisciplinary science, orbital logistics, international cooperation.^[34] Over 29 missions flew on subjects ranging from astronomy, microgravity, radar, and life sciences, to name a few.^[34] Spacelab hardware also supported missions such as Hubble (HST) servicing and space station resupply.^[34] STS-2 and STS-3 provided testing, and the first full mission was Spacelab-1 (STS-9) launched on November 28, 1983.^[34]
    Spacelab formally began in 1973, after a meeting in Brussels, Belgium, by European heads of state.^[18] Within the decade, Spacelab would go into orbit and provide not only Europe, but also the United States, with an orbital workshop