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{{Two other uses|the U.S. Space Transportation System|the NASA STS Program|Space Shuttle program|other space shuttles|Spaceplane}}
{{Infobox rocket
|image=STS120LaunchHiRes.jpg
|caption=Space Shuttle ''[[Space Shuttle Discovery|Discovery]]'' launches at the start of [[STS-120]].
|name=Space Shuttle
|function=Manned partially re-usable launch and reentry system
|manufacturer=[[United Space Alliance]]:<br />[[Thiokol]]/[[Alliant Techsystems]] (SRBs)<br />[[Lockheed Martin]] ([[Martin Marietta]]) – (ET)<br />[[Rockwell International|Rockwell]]/[[Boeing]] (orbiter)
|country-origin={{USA}}
|height=184 ft
|alt-height=56.1 m
|diameter=28.5 ft
|alt-diameter=8.69 m
|mass=4,470,000 lb
|alt-mass=2,030 t
|stages=2
|LEO-payload=24,400 kg
|alt-LEO=53,600 lb
|payload-location=[[Geostationary transfer orbit|GTO]]
|payload=3,810 kg
|alt-payload=8,390 lb
|status=Active
|sites=[[Kennedy Space Center Launch Complex 39|LC-39]], [[Kennedy Space Center]]<br />[[Vandenberg AFB Space Launch Complex 6|SLC-6]], [[Vandenberg Air Force Base|Vandenberg AFB]] (unused)
|launches=129
|success=128 <!-- Note these are labeled LAUNCH Successes, not mission successes. -->
|fail=1 ([[Space Shuttle Challenger disaster|launch failure]], ''[[Space Shuttle Challenger|Challenger]]'')<!-- LAUNCH failures only to match label in Infobox. -->
|partial=<!-- Partial Launch successes. -->
|other_outcome=1 ([[Space Shuttle Columbia disaster|re-entry failure]], ''[[Space Shuttle Columbia|Columbia]]'')
|payloads=[[Tracking and Data Relay Satellite]]s <br />[[Spacelab]] <br />[[Great Observatories program|Great Observatories]] <br />[[Galileo spacecraft|Galileo]] <br />[[Magellan probe|Magellan]] <br />[[International Space Station|Space Station components]]
|first=April 12, 1981
|plannedretirement=2010
|boosters=2
|boostername=[[Space Shuttle Solid Rocket Booster|Solid Rocket Boosters]]
|boosterengines=1 [[Solid-fuel rocket|solid]]
|boosterthrust=2,800,000 [[pound force|lbf]] each, [[sea level]] liftoff
|alt-boosterthrust=12.5 [[meganewton|MN]]
|boosterSI=269 s
|boostertime=124 s
|boosterfuel=solid
|stage1name=[[Shuttle External Tank|External Tank]]
|stage1engines=(none) <br />(3 [[Space Shuttle main engine|SSME]]s located on Orbiter)
|stage1thrust=1,225,704 lbf total, sea level liftoff
|alt-stage1thrust=5.45220 MN
|stage1SI=455 s
|stage1time=480 s
|stage1fuel=[[Liquid oxygen|LOX]]/[[Liquid hydrogen|LH2]]
|stage2name=[[Space Shuttle Orbiter|Orbiter]]
|stage2engines=2 [[Orbital Maneuvering System|OME]]
|stage2thrust=53.4 kN combined total vacuum thrust
|alt-stage2thrust=12,000 lbf
|stage2SI=316 s
|stage2time=1250 s
|stage2fuel=[[Monomethylhydrazine|MMH]]/[[Dinitrogen tetroxide|N<sub>2</sub>O<sub>4</sub>]]
}}

The '''Space Shuttle''', part of the '''Space Transportation System''' ('''STS'''), is an American [[spacecraft]] operated by [[NASA]] for orbital [[human spaceflight]] missions. The first of four test flights occurred in 1981, which were followed by operational flights beginning in 1982. The system is scheduled to be retired from service in 2010 after 134 launches. Major missions have included launching numerous satellites and interplanetary probes, conducting space science experiments, and servicing and construction of space stations. The Shuttle has been used for orbital space missions by NASA, the U.S. Department of Defense, the European Space Agency, and Germany. The United States funded STS development and shuttle operations.

At launch, the Space Shuttle consists of a dark orange-colored [[Space Shuttle external tank|external tank]] (ET);<ref name="et_paint1">[http://www.msfc.nasa.gov/news/news/releases/1999/99-193.html "NASA Takes Delivery of 100th Space Shuttle External Tank"]. NASA, August 16, 1999. Quote: "…orange spray-on foam used to insulate…"</ref><ref name="et_paint2">[http://www.nasa.gov/home/hqnews/2004/dec/HQ_04hh_external_tank.html "Media Invited To See Shuttle External Fuel Tank Ship From Michoud"]. NASA, December 28, 2004. Quote: "The gigantic, rust-colored external tank…"</ref> two white, slender [[Space Shuttle Solid Rocket Booster|Solid Rocket Boosters]] (SRBs); and the STS [[Space Shuttle orbiter|Orbiter Vehicle]] (OV) which contains the crew and payload. Payloads can be launched into higher orbits with either of two different booster stages developed for STS (1 stage PAM or 2 stage IUS).

The shuttle stack launches vertically like a conventional rocket from a mobile launch platform. It lifts off under the power of its two solid rocket boosters (SRBs) and its three main engines (SSMEs), the latter fueled by liquid hydrogen and liquid oxygen from the external tank. The Space Shuttle has a two stage ascent. The boosters are used only for the first stage, while the main engines burn for both stages. About two minutes after liftoff, staging occurs: the SRBs are released, and shortly begin falling into the ocean to be retrieved for reuse. The shuttle orbiter and external tank continue to ascend under power from the three main engines and their inertia. Upon reaching orbit, the main engines are shut down, and the external tank is jettisoned downward and falls to burn up in the atmosphere. However, it is possible for it to be re-used in orbit for various applications.<ref name=etuse/> At this point, the orbital maneuvering system (OMS) engines may be used to adjust or circularize the achieved orbit.

The orbiter carries [[astronaut]]s and payload such as satellites or space station parts into [[low earth orbit]], into the Earth's upper atmosphere or [[thermosphere]].<ref name="atmos">{{cite web|url=http://liftoff.msfc.nasa.gov/academy/space/atmosphere.html|title=Earth's Atmosphere|accessdate=October 25, 2007|dateformat=mdy|publisher=[[National Aeronautics and Space Administration]]|year=1995|author=NASA}}</ref> Usually, five to seven crew members ride in the orbiter. Two crew members, the Commander and Pilot, are sufficient for a minimal flight, as in the first four "test" flights, STS-1 through STS-4. A typical payload capacity is about {{convert|22700|kg|lb|sigfig=3|sp=us}}, but can be raised depending on the choice of launch configuration. The orbiter carries the payload in a large cargo bay with doors that open along the length of its top, a feature which makes the Space Shuttle unique among present spacecraft. This feature made possible the deployment of large satellites such as the [[Hubble Space Telescope]], and also to capture and return large payloads back to Earth.

When the orbiter's space mission is complete it fires its [[Orbital Maneuvering System]] (OMS) thrusters to drop out of orbit and [[Atmospheric reentry|re-enter]] the lower atmosphere.<ref name="atmos"/> During the descent, the shuttle orbiter passes through different layers of the atmosphere and decelerates from [[hypersonic]] speed primarily by [[aerobraking]]. In the lower atmosphere and landing phase, it acts as a [[Glider aircraft|glider]] with [[reaction control system]] (RCS) thrusters and [[fly-by wire]] controlled hydraulically actuated flight surfaces controlling its descent. It then makes a landing on a long runway as a [[spaceplane]]. The aerodynamic shape is a compromise between the demands of radically different speeds and air pressures during re-entry, subsonic atmospheric flight, and hypersonic flight. As a result the orbiter has a high sink rate at low altitudes, and transitions from using RCS thrusters in low pressure to flight surfaces at low altitudes.

With more than 2.5 million parts, the Space Shuttle has been called the most complex machine yet created by humanity.<ref name="parts">{{cite web|url=http://spaceflight.nasa.gov/shuttle/upgrades/upgrades5.html|title=The 21st Century Space Shuttle — Fun Facts |accessdate=January 11, 2010|dateformat=mdy|publisher=[[National Aeronautics and Space Administration]]|author=NASA}}</ref>

==Early history==
Though design and construction of the Space Shuttle began in the early 1970s, conceptualization actually began two decades earlier, even before the [[Apollo program]] of the 1960s.<ref>Please refer to [[Space Shuttle design process]].</ref><ref name="X15">Please refer also to [[North American X-15#Design_and_development]].</ref> The conceptual idea of a [[spacecraft]] returning from [[space]] to a horizontal landing begins within [[NACA]], in 1954,<ref name="X15" /> in the form of an [[aeronautics]] research experiment later to be named the [[North American X-15|X-15]]. The NACA proposal was submitted by [[Walter Dornberger]].<ref name="X15" />

In 1957, the X-15 concept further developed into another [[X-plane|X-series]] [[spaceplane]] proposal, called the [[X-20 Dyna-Soar|X-20]], which was never constructed.<ref name="X20">Please refer to [[X-20 Dyna-Soar]].</ref> [[Neil Armstrong]] was selected to pilot both the X-15 and the X-20.<ref name="X15" /><ref name="X20" />

Though the X-20 was never built, another spaceplane design similar in function to the X-20 was constructed several years later and was delivered to NASA in January of 1966.<ref name="HL10">Please refer to [[Northrop HL-10]].</ref> It was called the [[Northrop HL-10|HL-10]].<ref name="HL10" /> "HL" designated its horizontal landing capability after returning from space.<ref name="HL10" />

In the mid-1960's the [[US Air Force]] conducted a series of classified studies on next-generation space transportation systems and concluded that semi-reusable designs were the best choice from an overall cost basis.<ref name="DC3">Please refer to [[North_American_DC-3#History]].</ref> They proposed a development program with an immediate start on a "Class I" vehicle based on expendable boosters, followed by a slower development of a "Class II" semi-reusable design, and perhaps a "Class III" fully-reusable design in the further future.<ref name="DC3" /> In 1967 [[George Mueller (NASA)|George Mueller]] held a one-day symposium at NASA headquarters to study the options.<ref name="DC3" /> Eighty people attended and presented a wide variety of potential 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).<ref name="DC3" /> At the same time, a separate [[Space Shuttle Main Engine]] (SSME) competition was held.<ref name="DC3" /> NASA offices in [[Houston]] and [[Huntsville]] jointly issued a [[Request for Proposal]] (RFP) for ILRV studies, requesting ideas for a [[spacecraft]] that could deliver a payload to orbit but also re-enter the atmosphere and safely fly back to Earth.<ref name="DC3" /> Included in the proposals was that of a two-stage design, featuring a large booster and a small orbiter, called the [[North_American_DC-3|DC-3]].

In 1969 [[President Nixon]] decided to proceed with Space Shuttle development.<ref>Please refer to [[Space_Shuttle_design_process#Decision-making_process]].</ref>

In August 1973, the [[Martin-Marietta_X-24#X-24B|X-24B]] proved that an unpowered spaceplane could re-enter Earth's atmosphere from space for a safe return to a horizontal landing.

{{see|Space Shuttle program|Space Shuttle design process}}

==Description==
The Space Shuttle is the first orbital [[spacecraft]] designed for [[Reusable launch system|reusability]]. It carries different payloads to [[low Earth orbit]], provides crew rotation for the [[International Space Station]] (ISS), and performs servicing missions. The orbiter can also recover [[satellite]]s and other payloads from orbit and return them to [[Earth]]. Each Shuttle was designed for a projected lifespan of 100 launches or ten years 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 classified 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.

[[File:Sts-127 landing.ogg|250px|thumb|left|[[Space Shuttle Endeavour]] STS-127 landing video]]
Six airworthy Space Shuttle orbiters have been built; the first, [[Space Shuttle Enterprise|''Enterprise'']], was not built for orbital space flight, and was used only for testing purposes. Five space-worthy orbiters were built: [[Space Shuttle Columbia|''Columbia'']], [[Space Shuttle Challenger|''Challenger'']], [[Space Shuttle Discovery|''Discovery'']], [[Space Shuttle Atlantis|''Atlantis'']], and [[Space Shuttle Endeavour|''Endeavour'']]. ''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'' [[Space Shuttle Challenger disaster|disintegrated]] 73 seconds after launch in 1986, and ''Endeavour'' was built as a replacement from structural spare components. ''Columbia'' [[Space Shuttle Columbia disaster|broke apart]] during re-entry in 2003.

Each Space Shuttle is a [[reusable launch system]] that is composed of three main assemblies: the reusable [[Space Shuttle Orbiter|Orbiter Vehicle]] (OV), the [[Space Shuttle External Tank|external tank]] (ET), and the two reusable [[Space Shuttle Solid Rocket Booster|solid rocket boosters]] (SRBs).<ref>[http://www.nasa.gov/returntoflight/system/system_STS.html Shuttle Basics]. NASA.</ref> The tank and boosters are jettisoned during ascent; only the orbiter enters orbit. The vehicle is launched vertically like a conventional rocket, and the orbiter glides to a horizontal landing, after which it is refurbished for reuse. The SRBs parachute back to earth, where they are collected from the ocean and refilled for another use. Although the external tanks have always been discarded, it is possible to take them into orbit and re-use them (such as for incorporation into a space station).<ref name=etuse>[http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940004970_1994004970.pdf NASA-CR-195281, "Utilization of the external tanks of the space transportation system"]. NASA, August 23–27, 1982.</ref><ref name=etuse2>[http://www.astronautix.com/craft/stsation.htm STS External Tank Station]. astronautix.com</ref>

[[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.<ref> [http://sciencepolicy.colorado.edu/admin/publication_files/resource-2656-2008.18.pdf ''The Rise and Fall of the Space Shuttle''], Book Review: Final Countdown: NASA and the End of the Space Shuttle Program by Pat Duggins, American Scientist, 2008, Vol. 96, No. 5, p. 32.</ref> However, two missions were paid for by [[Germany]], Spacelab [[STS-61-A|D-1]] and [[STS-55|D-2]] (for ''Deutschland'') with a mission control in [[Oberpfaffenhofen]], Germany.<ref>[http://www.damec.dk/vis.asp?id=44 ]</ref><ref>[http://www.eads.com/1024/en/investor/News_and_Events/news_ir/2008/20081128_eads_astrium_spacelab.html ]</ref>

At times, the orbiter itself is referred to as the Space Shuttle. Technically, this is a slight misnomer, as the actual "Space Transportation System" (Space Shuttle) is the combination of the orbiter, the external tank, and the two solid rocket boosters. Combined, these are referred to as the "Stack"; the components are assembled in the [[Vehicle Assembly Building]], which was originally built to assemble the Apollo Saturn V rocket stacks.

===Orbiter vehicle===
{{Main|Space Shuttle orbiter}}

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 [[elevon]]s, 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, control the orbiter during descent and landing.

The orbiter has a large payload bay measuring {{convert|15|by|60|ft|m|sigfig=2|sp=us}} comprising most of the [[fuselage]]. 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 engine]]s (SSMEs) are mounted on the orbiter's aft fuselage in a triangular pattern. The three engines 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 and steer the shuttle as well as push. The orbiter structure is made primarily from [[Aluminium|aluminum]] [[alloy]], although the engine thrust structure is made primarily from [[titanium]] alloy.

The orbiter can 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 add-ons like the [[Extended Duration Orbiter]], [[Multi-Purpose Logistics Module]]s, and [[Canadarm]] (RMS).

The space-capable orbiters built are [[Space Shuttle Challenger|OV-099 ''Challenger'']], [[Space Shuttle Columbia|OV-102 ''Columbia'']], [[Space Shuttle Discovery|OV-103 ''Discovery'']], [[Space Shuttle Atlantis|OV-104 ''Atlantis'']], and [[Space Shuttle Endeavour|OV-105 ''Endeavour'']].<ref>{{cite web |url = http://science.ksc.nasa.gov/shuttle/resources/orbiters/orbiters.html |title = Orbiter Vehicles |publisher=NASA Kennedy Space Center |accessdate = 2009-10-11 }}</ref>

'''Orbiter add-ons:'''
<center><gallery>
File:Mplm in shuttle.jpg|MPLM ''Leonardo''
File:1989 s34 Galileo Deploy2.jpg|IUS deploying with Galileo
File:SBS-3 with PAM-D stage.jpg|PAM-D with satellite
Image:EDO pallet.jpg|EDO being installed
File:Spacelab Module in Cargo Bay.jpg|Spacelab in orbit
File:1996 s72 Scott EVA.jpg|RMS (Canadarm)
</gallery></center>

===Solid Rocket Boosters===
{{Main|Space Shuttle Solid Rocket Booster}}

Two solid rocket boosters (SRBs) each provide 12.5 million newtons (2.8 million lbf) of thrust at liftoff,<ref name="Columbia Accid Report D.7">[http://caib.nasa.gov/news/report/pdf/vol2/part07.pdf Columbia Accident Investigation Board Report, Vol II, Appendix D.7]. NASA, October 2003.</ref> which is 83% of the total thrust needed for liftoff. The SRBs are jettisoned two minutes after launch at a height of about {{convert|150000|ft|km|sigfig=2|sp=us}}, and then deploy parachutes and land in the ocean to be recovered.<ref>{{cite web|title=NASA Space Shuttle Columbia Launch|url=http://www.asterpix.com/console?as=1203639196321-20328515dc }}</ref> The SRB cases are made of steel about <sup>1</sup>&frasl;<sub>2</sub>&nbsp;inch (13&nbsp;mm) thick.<ref>{{cite web|author=NASA|url=http://history.nasa.gov/rogersrep/v2appl2b.htm|title=Report of the Presidential Commission on the Space Shuttle Challenger Accident|publisher=NASA}}</ref> The Solid Rocket Boosters are re-used many times; the casing used in [[Ares I]] engine testing in 2009 consisted of motor cases that have been flown, collectively, on 48 shuttle missions, including [[STS-1]].<ref>[http://www.nasa.gov/mission_pages/constellation/ares/09-053.html NASA Ares I First Stage Motor to be Tested August 25]. NASA, July 20, 2009.</ref>

===Flight systems===
Early shuttle missions took along the [[GRiD Compass]], arguably one of the first [[laptop]] computers. The Compass sold poorly, as it cost at least [[United States dollar|US$]]8000, but it offered unmatched performance for its weight and size.<ref name="GRiD">{{cite web|url=http://www.computerhistory.org/events/index.php?id=1139464298|title=Pioneering the Laptop:Engineering the GRiD Compass|accessdate=October 25, 2007|dateformat=mdy|publisher=The Computer History Museum|year=2006|author=The Computer History Museum}}</ref> NASA was one of its main customers.<ref name="GRiDNASA">{{cite web|url=http://ntrs.nasa.gov/search.jsp?R=499112&id=1&qs=Ntt%3DGRiD%252BCompass%26Ntk%3Dall%26Ntx%3Dmode%2520matchall%26N%3D0%26Ns%3DHarvestDate%257c1|title=Portable Computer|accessdate=October 26, 2007|dateformat=mdy|publisher=NASA|year=1985|author=NASA}}</ref>

The shuttle was one of the earliest craft to use a computerized [[fly-by-wire]] digital [[flight control system]]. This means no mechanical or hydraulic linkages connect the pilot's control stick to the control surfaces or [[reaction control system]] thrusters.

A primary concern with digital fly-by-wire systems is reliability. Much research went into the shuttle computer system. The shuttle uses five identical redundant IBM 32-bit general purpose computers (GPCs), model [[IBM AP-101|AP-101]], constituting a type of [[embedded system]]. Four computers run specialized software called the Primary Avionics Software System (PASS). A fifth backup computer runs separate software called the Backup Flight System (BFS). Collectively they are called the Data Processing System (DPS).<ref name="LogicD">{{cite web|publisher=NASA Office of Logic Design|url=http://www.klabs.org/mapld06/abstracts/139_ferguson_a.html|title=Implementing Space Shuttle Data Processing System Concepts in Programmable Logic Devices|accessdate=2006-08-27|author=Ferguson, Roscoe C.|coauthors=Robert Tate and Hiram C. Thompson}}</ref><ref name="ibm">{{cite web|url=http://www-03.ibm.com/ibm/history/exhibits/space/space_shuttle.html|title=IBM and the Space Shuttle|dateformat=mdy|accessdate=August 27, 2006|author=IBM|publisher=[[IBM]]}}</ref>

The design goal of the shuttle's DPS is fail-operational/fail-safe reliability. After a single failure, the shuttle can still continue the mission. After two failures, it can still land safely.

The four general-purpose computers operate essentially in lockstep, checking each other. If one computer fails, the three functioning computers "vote" it out of the system. This isolates it from vehicle control. If a second computer of the three remaining fails, the two functioning computers vote it out. In the rare case of two out of four computers simultaneously failing (a two-two split), one group is picked at random.
[[Image:Atlantis is landing after STS-30 mission.jpg|thumb|left|''Atlantis'' deploys [[landing gear]] before landing on a selected runway just like a common aircraft.]]

The Backup Flight System (BFS) is separately developed software running on the fifth computer, used only if the entire four-computer primary system fails. The BFS was created because although the four primary computers are hardware redundant, they all run the same software, so a generic software problem could crash all of them. [[Embedded system]] [[Avionics|avionic]] software is developed under totally different conditions from public commercial software: the number of code lines is tiny compared to a public commercial software, changes are only made infrequently and with extensive testing, and many programming and test personnel work on the small amount of computer code. However, in theory it can still fail, and the BFS exists for that contingency. While BFS will run in parallel with PASS, to date, BFS has never been engaged to take over control from PASS during any shuttle mission.

The software for the shuttle computers is written in a high-level language called [[HAL/S]], somewhat similar to [[PL/I]]. It is specifically designed for a [[Real-time computing|real time]] [[embedded system]] environment.

The IBM AP-101 computers originally had about 424 kilobytes of [[magnetic core memory]] each. The CPU could process about 400,000 instructions per second. They have no hard disk drive, and load software from magnetic tape cartridges.

In 1990, the original computers were replaced with an upgraded model AP-101S, which has about 2.5 times the memory capacity (about 1 megabyte) and three times the processor speed (about 1.2 million instructions per second). The memory was changed from magnetic core to semiconductor with battery backup.
[[Image:Shuttle Patch.svg|thumb|left|Space Shuttle program [[insignia]]]]

===Markings and insignia===
The [[typeface]] used on the Space Shuttle Orbiter is [[Helvetica]].<ref>{{cite video
|date=2007-09-12
|title=[[Helvetica (film)|Helvetica]]
|medium=[[Documentary film|Documentary]]
}}</ref> On the side of the shuttle between the cockpit windows and the cargo bay doors is the name of the orbiter. Underneath the rear of the cargo bay doors is the [[NASA logo|NASA insignia]], the text 'United States' and a [[flag of the United States]]. Another United States flag appears on the right wing.

===Upgrades===
[[Image:STSCPanel.jpg|thumb|During [[STS-101]], [[Space Shuttle Atlantis|''Atlantis'']] was the first shuttle to fly with a [[glass cockpit]].]]

The Space Shuttle is a 1970s-era [[spacecraft]]<ref name="shuttle_sale">{{cite news|url=http://abcnews.go.com/Technology/wireStory?id=9574776|title=Recession Special: NASA Cuts Space Shuttle Price|last=Dunn|first=Marcia|date=January 15, 2010|publisher=''[[ABC News]]''|accessdate=January 15, 2010}}</ref> and has received many upgrades and modifications since then for improvements ranging from performance and reliability to safety. Internally, the shuttle remains largely similar to the original design, with the exception of the improved avionics computers. In addition to the computer upgrades, the original analog primary flight instruments were replaced with modern full-color, flat-panel display screens, similar to those of contemporary airliners like the [[Airbus A380]] and [[Boeing 777]]. This is called a [[glass cockpit]]. Programmable calculators are carried as well (originally the [[HP-41C]]). With the coming of the ISS, the orbiter's internal airlocks have been replaced with external docking systems to allow for a greater amount of cargo to be stored on the shuttle's mid-deck during station resupply missions.

The [[Space Shuttle Main Engine]]s (SSMEs) have had several improvements to enhance reliability and power. This explains phrases such as "Main engines throttling up to 104%." This does not mean the engines are being run over a safe limit. The 100% figure is the original specified power level. During the lengthy development program, [[Rocketdyne]] determined the engine was capable of safe reliable operation at 104% of the originally specified thrust. They could have rescaled the output number, saying in essence 104% is now 100%. To clarify this would have required revising much previous documentation and software, so the 104% number was retained. SSME upgrades are denoted as "block numbers", such as block I, block II, and block IIA. The upgrades have improved engine reliability, maintainability and performance. The 109% thrust level was finally reached in flight hardware with the Block II engines in 2001. The normal maximum throttle is 104%, with 106% or 109% used for mission aborts.

For the first two missions, [[STS-1]] and [[STS-2]], the [[Space Shuttle external tank|external tank]] was painted white to protect the insulation that covers much of the tank, but improvements and testing showed that it was not required. The weight saved by not painting the tank results in an increase in payload capability to orbit.<ref name="aerospaceweb">{{cite web|url=http://www.aerospaceweb.org/question/spacecraft/q0285.shtml|title=Space Shuttle External Tank Foam Insulation |accessdate=October 25, 2007 |dateformat=mdy |publisher=Aerospaceweb.org |year=2006 |author=Aerospaceweb.org}}</ref> Additional weight was saved by removing some of the internal "stringers" in the hydrogen tank that proved unnecessary. The resulting "light-weight external tank" has been used on the vast majority of shuttle missions. [[STS-91]] saw the first flight of the "super light-weight external tank". This version of the tank is made of the 2195 aluminum-lithium alloy. It weighs 3.4 metric tons (7,500&nbsp;lb) less than the last run of lightweight tanks. As the shuttle cannot fly unmanned, each of these improvements has been "tested" on operational flights.

The SRBs (Solid Rocket Boosters) have undergone improvements as well. Design engineers added a third [[O-ring]] seal to the joints between the segments after the [[Space Shuttle Challenger disaster|Space Shuttle ''Challenger'' disaster]].
[[Image:SSME1.jpg|thumb|upright|left|The three nozzles of the [[Space shuttle main engine|Main Engine cluster]] with the two [[Orbital Maneuvering System]] (OMS) pods, and the [[vertical stabilizer]] above.]]

Several other SRB improvements were planned in order to improve performance and safety, but never came to be. These culminated in the considerably simpler, lower cost, probably safer and better performing [[Space Shuttle Solid Rocket Booster#Advanced Solid Rocket Booster|Advanced Solid Rocket Booster]]. These rockets entered production in the early to mid-1990s to support the Space Station, but were later canceled to save money after the expenditure of $2.2 billion.<ref>{{cite web |author=Encyclopedia Astronautica|url=http://www.astronautix.com/lvfam/shuttle.htm|title=Shuttle|publisher=Encyclopedia Astronautica}}</ref> The loss of the ASRB program resulted in the development of the Super LightWeight external Tank (SLWT), which provides some of the increased payload capability, while not providing any of the safety improvements. In addition, the Air Force developed their own much lighter single-piece SRB design using a filament-wound system, but this too was canceled.

[[STS-70]] was delayed in 1995, when [[woodpecker]]s bored holes in the foam insulation of ''Discovery'''s external tank. Since then, NASA has installed commercial plastic owl decoys and inflatable owl balloons which must be removed prior to launch.<ref>{{cite web|url=http://science.ksc.nasa.gov/shuttle/missions/sts-70/woodpecker.html|title=Woodpeckers damage STS-70 External Tank|accessdate=2006-08-27|author=Jim Dumoulin|publisher=NASA}}</ref> The delicate nature of the foam insulation has been the cause of damage to the [[Space Shuttle thermal protection system|Thermal Protection System]], the tile heat shield and heat wrap of the orbiter, during recent launches. NASA remains confident that this damage, while it was the primary cause of the [[Space Shuttle Columbia disaster|Space Shuttle ''Columbia'' disaster]] on February 1, 2003, will not jeopardize the objective of NASA to complete the [[International Space Station]] (ISS) in the projected time allotted.

A cargo-only, unmanned variant of the shuttle has been variously proposed, and rejected since the 1980s. It was called the [[Shuttle-C]], and would have traded re-usability for cargo capability, with large potential savings from reusing technology developed for the Space Shuttle.

On the first four shuttle missions, astronauts wore modified U.S. Air Force high-altitude full-pressure suits, which included a full-pressure helmet during ascent and descent. From the fifth flight, [[STS-5]], until the loss of [[Space Shuttle Challenger disaster|''Challenger'']], one-piece light blue [[nomex]] flight suits and partial-pressure helmets were worn. A less-bulky, partial-pressure version of the high-altitude pressure suits with a helmet was reinstated when shuttle flights resumed in 1988. The Launch-Entry Suit ended its service life in late 1995, and was replaced by the full-pressure [[Advanced Crew Escape Suit]] (ACES), which resembles the [[Gemini space suit]] worn in the mid-1960s.

To extend the duration that orbiters can stay docked at the ISS, the [[Station-to-Shuttle Power Transfer System]] (SSPTS) was installed. The SSPTS allows these orbiters to use power provided by the ISS to preserve their consumables. The SSPTS was first used successfully on [[STS-118]].

===Technical data===
[[File:Space Shuttle Orbiter-Illustration.jpg|thumb|300px|Space Shuttle orbiter illustration]]
[[File:Plánik orbitera 2.JPG|thumb|300px|Space Shuttle drawing]]
[[File:Shuttle Left Wing Cutaway Diagram.jpg|thumb|Space Shuttle wing cutaway]]
[[Image:Atlantis on Shuttle Carrier Aircraft.jpg|thumb|[[Space Shuttle Atlantis|Space Shuttle ''Atlantis'']] transported by a [[Boeing 747]] [[Shuttle Carrier Aircraft]] (SCA), 1998 (NASA).]]
[[Image:Space Shuttle Transit.jpg|thumb|[[Space Shuttle Endeavour|Space Shuttle ''Endeavour'']] being transported by a [[Boeing 747]].]]
[[Image:Space Shuttle vs Soyuz TM - to scale drawing.png|thumb|Space Shuttle Orbiter and [[Soyuz-TM]] (drawn to scale).]]
[[Image:STS-79 rollout.jpg|right|thumb|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.]]
[[Image:MainSPStest.jpg|thumb|right|[[Water]] is released onto the mobile launcher platform on [[Launch Pad 39A]] at the start of a rare sound suppression system test in 2004. During launch, 300,000 US [[gallon]]s (1,100 m³) are poured onto the pad in only 41 seconds.]]
[[Image:Space shuttles Atlantis (STS-125) and Endeavour (STS-400) on launch pads.jpg|thumb|200px|upright|Two Space Shuttles sit at launch pads. This particular occasion is due to the final Hubble servicing mission, where the International Space Station is unreachable, necessitating having a Shuttle on standby for a possible rescue mission.]]

'''Orbiter specifications'''<ref name="tech">{{cite book|last=Jenkins |first=Dennis R. |title=Space Shuttle: The History of the National Space Transportation System |publisher=Voyageur Press |edition= |date=2007 |pages= |isbn=0963397451}}</ref> (for ''Endeavour'', OV-105)
*Length: {{convert|122.17|ft|m|abbr=on|sigfig=5}}
*Wingspan: {{convert|78.06|ft|m|abbr=on|sigfig=4}}
*Height: {{convert|58.58|ft|abbr=on|sigfig=4}}
*Empty weight: {{convert|172000|lb|kg|abbr=on|sigfig=3}}<ref>{{cite web|url=http://www-pao.ksc.nasa.gov/shuttle/resources/orbiters/endeavour.html |title=John F. Kennedy Space Center - Space Shuttle Endeavour |publisher=Pao.ksc.nasa.gov |date= |accessdate=2009-07-17}}</ref>
*Gross liftoff weight: {{convert|240000|lb|kg|abbr=on|sigfig=2}}
*Maximum landing weight: {{convert|230000|lb|kg|abbr=on|sigfig=2}}
*Main engines: Three Rocketdyne Block IIA SSMEs, each with a sea level [[thrust]] of {{convert|393800|lbf|MN|abbr=on|sigfig=4}} at 104% power <!--393,800 lbf per reference listed above.-->
*Maximum payload: {{convert|55250|lb|kg|abbr=on|sigfig=4}}
*Payload bay dimensions: {{convert|15|by|59|ft|m|abbr=on|sigfig=2}}
*Operational altitude: {{convert|100|to|520|nmi|km mi|lk=in|abbr=on|sigfig=2}}
*Speed: {{convert|7743|m/s|km/h mph|abbr=on|lk=on|sigfig=4}}
*Crossrange: {{convert|1085|nmi|km mi|abbr=on|sigfig=4}}
*Crew: Varies. The earliest shuttle flights had the minimum crew of two; many later missions a crew of five. Today, typically seven people fly ([[commander]], [[Aviator|pilot]], several [[mission specialist]]s, and rarely a [[flight engineer]]). On two occasions, eight astronauts have flown ([[STS-61-A]], [[STS-71]]). Eleven people could be accommodated in an emergency mission (see [[STS-3xx]]).

'''External tank specifications''' (for SLWT)
*Length: {{convert|46.9|m|ft|abbr=on|sigfig=3}}
*Diameter: {{convert|8.4|m|ft|abbr=on|sigfig=2}}
*Propellant volume: {{convert|2025|m3|USgal|abbr=on|sigfig=4}}
*Empty weight: {{convert|26535|kg|lb|abbr=on|sigfig=5}}
*Gross liftoff weight: {{convert|756000|kg|lb|abbr=on|sigfig=3}}

'''Solid Rocket Booster specifications'''
*Length: {{convert|45.46|m|ft|abbr=on|sigfig=3}}<ref name="Jenkins_3rd">{{cite book|last=Jenkins |first=Dennis R. |title=Space Shuttle: The History of the National Space Transportation System |publisher=Voyageur Press |edition=Third |date=2002 |pages= |isbn=0-9633974-5-1}}</ref>
*Diameter: {{convert|3.71|m|ft|abbr=on|sigfig=3}}<ref name="Jenkins_3rd"/>
*Empty weight (per booster): {{convert|68000|kg|lb|abbr=on|sigfig=3}}<ref name="Jenkins_3rd"/>
*Gross liftoff weight (per booster): {{convert|571000|kg|lb|abbr=on|sigfig=3}}<ref name=STS_prop_systems>[http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19910018886_1991018886.pdf Space Shuttle Propulsion Systems], p. 153. NASA, June 26, 1990.</ref>
*Thrust (at liftoff, sea level): {{convert|12.5|MN|lbf|abbr=on|lk=on|sigfig=2}}<ref name="Columbia Accid Report D.7"/>

'''System Stack specifications'''
*Height: {{convert|56|m|ft|abbr=on|sigfig=2}}
*Gross liftoff weight: {{convert|2000000|kg|lb|abbr=on|sigfig=2}}
*Total liftoff thrust: {{convert|30.16|MN|lbf|abbr=on|sigfig=3}}

==Mission profile==
===Launch===
All Space Shuttle missions are launched from [[Kennedy Space Center]] (KSC). The same [[launch commit criteria|weather criteria used for launch]] are also for end of mission landing at KSC, and include precipitation (none allowed at the launch pad or flight path), temperatures above 99 °F (37 °C) or below 35 °F (2 °C), a 20% or greater chance of lightning within 5 nautical miles (9 km) and cloud cover allows direct visual observation of the shuttle through 8,000 feet.<ref name="weather launch criteria">{{cite web|url=http://www-pao.ksc.nasa.gov/kscpao/release/1999/39-99.htm|title=SPACE SHUTTLE WEATHER LAUNCH COMMIT CRITERIA AND KSC END OF MISSION WEATHER LANDING CRITERIA|work=KSC Release No. 39-99|publisher=NASA Kennedy Space Center|accessdate=2009-07-06}}</ref> The shuttle will not be launched under conditions where it could be struck by [[lightning]]. Aircraft are often struck by lightning with no adverse effects because the [[electricity]] of the strike is dissipated through its conductive structure and the aircraft is not electrically [[Ground (electricity)|grounded]]. Like most jet airliners, the shuttle is mainly constructed of conductive aluminum, which would normally shield and protect the internal systems. However, upon takeoff the shuttle sends out a long exhaust plume as it ascends, and this plume can trigger lightning by providing a current path to ground. The NASA Anvil Rule for a shuttle launch states that an [[anvil cloud]] cannot appear within a distance of 10 [[nautical miles]].<ref>Weather at About.com. [http://weather.about.com/od/thunderstormsandlightning/f/anvilrule.html What is the Anvil Rule for Thunderstorms?]. Retrieved 2008-06-10.</ref> The Shuttle Launch Weather Officer will monitor conditions until the final decision to scrub a launch is announced. In addition, the weather conditions must be acceptable at one of the Transatlantic Abort Landing sites (one of several [[Space Shuttle abort modes]]) to launch as well as the solid rocket booster recovery area.<ref name="weather launch criteria" /><ref>NASA Launch Blog. [http://www.nasa.gov/mission_pages/shuttle/launch/sts-121/launch-vlcc_070106.html ]. Retrieved 2008-06-10.</ref> While the shuttle might safely endure a lightning strike, a [[Apollo 12#Mission highlights|similar strike caused problems on Apollo 12]], so for safety [[NASA]] chooses not to launch the shuttle if lightning is possible (NPR8715.5).

[[Image:Sts mprof.jpg|thumb|left|STS [[Space mission|mission]] profile]]

Historically, the Shuttle was not launched if its flight would run from December to January (a year-end rollover or YERO). Its flight software, designed in the 1970s, was not designed for this, and would require the orbiter's computers be reset through a change of year, which could cause a glitch while in orbit. In 2007, NASA engineers devised a solution so Shuttle flights could cross the year-end boundary.<ref name="YERO">{{cite web |last=Bergin |first=Chris |title=NASA solves YERO problem for shuttle |url=http://www.nasaspaceflight.com/content/?cid=5026 |date=February 19, 2007 |accessdate=2007-12-22 }}</ref>

On the day of a launch, after the final hold in the countdown at T minus 9 minutes, the Shuttle goes through its final preparations for launch, and the countdown is automatically controlled by the Ground Launch Sequencer (GLS), software at the Launch Control Center, which stops the count if it senses a critical problem with any of the Shuttle's on-board systems. The GLS hands off the count to the Shuttle's on-board computers at T minus 31 seconds, in a process called auto sequence start.

At T minus 16 seconds, the massive sound suppression system (SPS) begins to drench the [[Mobile Launcher Platform]] (MLP) and SRB trenches with {{convert|300000|USgal|m3|sigfig=2}} of water to protect the Orbiter from damage by [[acoustical]] energy and rocket exhaust reflected from the flame trench and MLP during liftoff.<ref name="sps">National Aeronautics and Space Administration. [http://www-pao.ksc.nasa.gov/kscpao/nasafact/count4ssws.htm "Sound Suppression Water System"] Revised 2000-08-28. Retrieved 2006-07-09.</ref>

At T-minus 10 seconds, hydrogen igniters are activated under each engine bell to quell the stagnant gas inside the cones before ignition. Failure to burn these gases can trip the onboard sensors and create the possibility of an overpressure and explosion of the vehicle during the firing phase. The main engine turbopumps also begin charging the combustion chambers with liquid hydrogen and liquid oxygen at this time. The computers reciprocate this action by allowing the redundant computer systems to begin the firing phase.
[[Image:Atlantis launch plume edit.jpg|thumb|left|upright|Shuttle launch of ''Atlantis'' at sunset in 2001. The sun is behind the camera, and the plume's shadow intersects the [[moon]] across the sky.]]

The three [[Space shuttle main engine|Space Shuttle Main Engines (SSMEs)]] start at T minus 6.6 seconds. The main engines ignite sequentially via the shuttle's general purpose computers (GPCs) at 120 millisecond intervals. The GPCs require that the engines reach 90% of their rated performance to complete the final gimbal of the main engine nozzles to liftoff configuration.<ref name="countdown101">National Aeronautics and Space Administration. [http://www.nasa.gov/mission_pages/shuttle/launch/countdown101.html "NASA - Countdown 101"]. Retrieved 2006-07-10.</ref> When the SSMEs start, the water from the sound suppression system flashes into a large volume of steam that shoots southward. All three SSMEs must reach the required 100% thrust within three seconds, otherwise the onboard computers will initiate an [[Space Shuttle abort modes#Redundant Set Launch Sequencer .28RSLS.29 Abort|RSLS abort]]. If the onboard computers verify normal thrust buildup, at T minus 0 seconds, the 8 [[Pyrotechnic fastener|pyrotechnic nuts]] holding the vehicle to the pad are detonated and the [[Space Shuttle Solid Rocket Booster|SRBs]] are ignited. At this point the vehicle is committed to takeoff, as the SRBs cannot be turned off once ignited.<ref>{{cite web|url=http://spaceflight.nasa.gov/shuttle/reference/shutref/srb/posts.html |title=HSF - The Shuttle |publisher=Spaceflight.nasa.gov |date= |accessdate=2009-07-17}}</ref> The plume from the solid rockets exits the flame trench in a northward direction at near the speed of sound, often causing a rippling of shockwaves along the actual flame and smoke contrails. At ignition, the GPCs mandate the firing sequences via the Master Events Controller, a computer program integrated with the shuttle's four redundant computer systems. There are extensive emergency procedures ([[Space Shuttle abort modes|abort modes]]) to handle various failure scenarios during ascent. Many of these concern SSME failures, since that is the most complex and highly stressed component. After the [[Space Shuttle Challenger disaster|Challenger disaster]], there were extensive upgrades to the abort modes.

After the main engines start, but while the solid rocket boosters are still clamped to the pad, the offset thrust from the Shuttle's three main engines causes the entire launch stack (boosters, tank and shuttle) to pitch down about 2 m at cockpit level. This motion is called the "nod", or "twang" in NASA jargon. As the boosters flex back into their original shape, the launch stack pitches slowly back upright. This takes approximately six seconds. At the point when it is perfectly vertical, the boosters ignite and the launch commences.

Shortly after clearing the tower the Shuttle begins a roll and pitch program to set its orbital inclination and so that the vehicle is below the external tank and SRBs, with wings level. The vehicle climbs in a progressively flattening arc, accelerating as the weight of the SRBs and main tank decrease. To achieve low orbit requires much more horizontal than vertical acceleration. This is not visually obvious, since the vehicle rises vertically and is out of sight for most of the horizontal acceleration. The near circular orbital velocity at the {{convert|380|km|mi|sigfig=3|sp=us}} altitude of the [[International Space Station]] is 7.68 kilometers per second {{convert|27650|km/h|mph|abbr=on|sigfig=4}}, roughly equivalent to Mach 23 at sea level. As the International Space Station orbits at an inclination of 51.6 degrees, the Shuttle has to set its inclination to the same value to rendezvous with the station.

[[Image:SSLV ascent.jpg|thumb|right|upright|SSLV at Mach 2.46 and {{convert|66000|ft|m|abbr=on|sigfig=2}}. The surface of the vehicle is colored by the pressure coefficient, and the gray contours represent the density of the surrounding air, as calculated using the [[Overflow (software)|overflow]] codes.]]

Around a point called [[Max Q]], where the aerodynamic forces are at their maximum, the main engines are temporarily throttled back to avoid [[overspeed (aircraft)|overspeeding]] and hence overstressing the Shuttle, particularly in vulnerable areas such as the wings. At this point, a phenomenon known as the [[Prandtl-Glauert singularity]] occurs, where condensation clouds form during the vehicle's transition to supersonic speed.

At ''T''+126 seconds after launch, [[explosive bolt]]s release the SRBs and small separation rockets push them laterally away from the vehicle. The SRBs parachute back to the ocean to be reused. The Shuttle then begins accelerating to orbit on the [[Space Shuttle main engine]]s. The vehicle at that point in the flight has a thrust-to-weight ratio of less than one{{ndash}} the main engines actually have insufficient thrust to exceed the force of gravity, and the vertical speed given to it by the SRBs temporarily decreases. However, as the burn continues, the weight of the propellant decreases and the thrust-to-weight ratio exceeds 1 again and the ever-lighter vehicle then continues to accelerate towards orbit.
[[Image:space shuttle glow.JPG|thumb|left|A picture taken of the [[afterglow]] from [[STS 119]] with colors varying from white to orange.]]

The vehicle continues to climb and takes on a somewhat nose-up angle to the horizon{{ndash}} it uses the main engines to gain and then maintain altitude while it accelerates horizontally towards orbit. At about five and three-quarter minutes into ascent, the orbiter rolls heads up to switch communication links from ground stations to [[Tracking and Data Relay Satellite]]s.

Finally, in the last tens of seconds of the main engine burn, the mass of the vehicle is low enough that the engines must be throttled back to limit vehicle acceleration to 3 ''g'' (30 m/s²), largely for astronaut comfort.

The main engines are shut down before complete depletion of propellant, as running dry would destroy the engines. The oxygen supply is terminated before the hydrogen supply, as the SSMEs react unfavorably to other shutdown modes. (Liquid oxygen has a tendency to react violently, and supports combustion when it encounters hot engine metal.) The external tank is released by firing explosive bolts and falls, largely burning up in the atmosphere, though some fragments fall into the ocean, in either the [[Indian Ocean]] or the [[Pacific Ocean]] depending on launch profile.<ref name="tech" /> The sealing action of the tank plumbing and lack of pressure relief systems on the external tank helps it break up in the lower atmosphere. After the foam burns away during reentry, the heat causes a pressure buildup in the remaining liquid oxygen and hydrogen until the tank explodes. This ensures that any pieces that fall back to Earth are small.

To prevent the shuttle from following the external tank back into the lower atmosphere, the [[Orbital maneuvering system]] (OMS) engines are fired to raise the perigee higher into the upper atmosphere. On some missions (e.g., missions to the ISS), the OMS engines are also used while the main engines are still firing. The reason for putting the orbiter on a path that brings it back to Earth is not just for external tank disposal but also one of safety: if the OMS malfunctions, or the cargo bay doors cannot open for some reason, the shuttle is already on a path to return to earth for an emergency abort landing.

===In orbit===
Once in orbit, the shuttle does any number of tasks, and usually some combination. In the 1980s and 1990s, many flights involved space science missions on the NASA/ESA [[Spacelab]], or launching various types of satellites and science probes. By the 1990s and 2000s the focus shifted more to servicing space stations, with fewer satellite launches. Most missions involve staying in orbit several days to two weeks, although longer missions are possible with the [[Extended Duration Orbiter]] add-on or when attached to a space station.

===Re-entry and landing===
{{Refimprovesect|date=June 2007}}
{{commonscat|Landings of space shuttles}}

Almost the entire Space Shuttle [[atmospheric reentry|re-entry]], except for lowering the landing gear and deploying the air data probes, is normally performed under computer control. However, the re-entry can be flown entirely manually if an emergency arises. The approach and landing phase can be controlled by the autopilot, but is usually hand flown.

The vehicle begins re-entry by firing the Orbital maneuvering system engines, while flying upside down, backside first, in the opposite direction to orbital motion for approximately three minutes, which reduces the shuttle's velocity by about {{convert|200|mph|km/h|abbr=on|sigfig=3}}. The resultant slowing of the Shuttle lowers its orbital [[perigee]] down into the upper atmosphere. The shuttle then flips over, by pushing its nose down (which is actually "up" relative to the Earth, because it's flying upside down). This OMS firing is done roughly halfway around the globe from the landing site.

The vehicle starts encountering more significant air density in the lower thermosphere at about {{convert|400000|ft|km|abbr=on|sigfig=2}}, at around [[Mach number|Mach]] 25, {{convert|8200|m/s|km/h mph|abbr=on|sigfig=2}}. The vehicle is controlled by a combination of [[Reaction Control System|RCS thrusters]] and control surfaces, to fly at a 40 degree nose-up attitude, producing high drag, not only to slow it down to landing speed, but also to reduce reentry heating. As the vehicle encounters progressively denser air, it begins a gradual transition from spacecraft to aircraft. In a straight line, its 40 degree nose-up attitude would cause the descent angle to flatten-out, or even rise. The vehicle therefore performs a series of four steep S-shaped banking turns, each lasting several minutes, at up to 70 degrees of bank, while still maintaining the 40 degree angle of attack. In this way it dissipates speed sideways rather than upwards. This occurs during the 'hottest' phase of re-entry, when the heat-shield glows red and the G-forces are at their highest. By the end of the last turn, the transition to aircraft is almost complete. The vehicle levels its wings, lowers its nose into a shallow dive and begins its approach to the landing site.

<center><gallery>
Image:Stsheat.jpg|[[Simulation]] of the outside of the Shuttle as it heats up to over 1,500&nbsp; °C during re-entry.
Image:Nasa Shuttle Test Using Electron Beam full.jpg|A Space Shuttle model undergoes a [[wind tunnel]] test in 1975. This test is simulating the ionized gasses that surround a shuttle as it reenters the atmosphere.
Image:CFD Shuttle.jpg|A [[computer]] simulation of high velocity air flow around the Space Shuttle during re-entry.
</gallery></center>

The orbiter's maximum [[glide ratio]]/[[lift-to-drag ratio]] varies considerably with speed, ranging from 1:1 at [[hypersonic]] speeds, 2:1 at supersonic speeds and reaching 4.5:1 at subsonic speeds during approach and landing.<ref>http://klabs.org/DEI/Processor/shuttle/shuttle_tech_conf/1985008580.pdf</ref>

In the lower atmosphere, the orbiter flies much like a conventional glider, except for a much higher descent rate, over {{convert|50|m/s|km/h mph|abbr=on|sigfig=2|sp=us}}. At approximately Mach 3, two air data probes, located on the left and right sides of the orbiter's forward lower fuselage, are deployed to sense air pressure related to the vehicle's movement in the atmosphere.

When the approach and landing phase begins, the orbiter is at a {{convert|3000|m|ft|abbr=on|sigfig=2}} altitude, {{convert|12|km|mi|abbr=on}} from the runway. The pilots apply aerodynamic braking to help slow down the vehicle. The orbiter's speed is reduced from {{convert|682|to|346|km/h|mph|abbr=on}}, approximately, at touch-down (compared to {{convert|260|km/h|mph|abbr=on}} for a jet airliner). The landing gear is deployed while the Orbiter is flying at {{convert|430|km/h|mph|abbr=on}}. To assist the speed brakes, a {{convert|12|m|ft|abbr=on|sigfig=2}} drag chute is deployed either after main gear or nose gear touchdown (depending on selected chute deploy mode) at about {{convert|343|km/h|mph|abbr=on|sigfig=3}}. The chute is jettisoned once the orbiter slows to {{convert|110|km/h|mph|abbr=on|sigfig=3}}.

After landing, the vehicle stands on the runway for several minutes to permit the fumes from poisonous [[hydrazine]] (which is used as a fuel for [[aircraft attitude|attitude]]<!-- ATTITUDE not ALTITUDE!!! --> [[reaction control system|control]]<!-- Yeah, yeah, the RCS can control yaw as well -->, and the orbiter's three [[Auxiliary Power Unit|APUs]]) to dissipate, and for the shuttle fuselage to cool before the astronauts disembark.

<center><gallery>
Image:STS-95 landing.jpg|[[Space Shuttle Discovery|''Discovery'']] touches down at the end of [[STS-95]].
Image:STS-73 landing.jpg|[[Space Shuttle Columbia|''Columbia'']] lands at Kennedy Space Center at the end of [[STS-73]].
Image:Space Shuttle Endeavour landing.jpg|[[Space Shuttle Endeavour|''Endeavour'']] brake chute deploys after touching down
Image:Discovery mission completed q.jpg| ''Discovery'' after landing on Earth for crew disembarkment
</gallery></center>

===Landing sites===
{{seealso|List of space shuttle landing runways}}

Space Shuttle landings are always planned for [[Kennedy Space Center]].{{Citation needed|date=June 2009}} If weather conditions make landing there unfavorable, the shuttle can delay its landing until conditions are favorable, touch down at [[Edwards Air Force Base]], [[California]], or use one of the multiple alternate landing sites around the world. A landing at any site other than Kennedy Space Center means that after touchdown the shuttle must be mated to the [[Shuttle Carrier Aircraft]] and returned to [[Cape Canaveral]]. Space Shuttle ''Columbia'' ([[STS-3]]) landed at the [[White Sands Space Harbor]], [[New Mexico]]; this is viewed as a last resort as NASA scientists believe that the sand could potentially damage the shuttle's exterior.

There are many [[Space Shuttle abort modes#Emergency landing sites|alternative landing sites]] that have never been used.<ref>{{cite web |author=Global Security |publisher=GlobalSecurity.org |url=http://www.globalsecurity.org/space/facility/sts-els.htm |title=Space Shuttle Emergency Landing Sites |accessdate=2007-08-03}}</ref><ref>{{cite web |author=US Northern Command |url=http://www.northcom.mil/News/2009/031309_a.html |title=DOD Support to manned space operations for STS-119 }}</ref>

==Fleet history==
{{Main|List of space shuttle missions}}

Below is a list of major events in the Space Shuttle orbiter fleet.
[[File:OV-101 first flight.jpg|thumb|right|OV-101 ''Enterprise'' takes flight for the first time over [[Dryden Flight Research Facility]], Edwards, California in 1977 as part of the Shuttle program's [[Approach and Landing Tests]] (ALT).]]

{|class="wikitable" border="1" style="font-size:90%;"
|+ '''Space Shuttle major events'''
|-
! Date
! Orbiter
! Major event / remarks
|-
| February 18, 1977
| [[Space Shuttle Enterprise|''Enterprise'']]
| First flight; Attached to [[Shuttle Carrier Aircraft]] throughout flight.
|-
| August 12, 1977
| ''Enterprise''
| First free flight; Tailcone on; lakebed landing.
|-
| October 12, 1977
| ''Enterprise''
| Third free flight; First with no tailcone; lakebed landing.
|-
| October 26, 1977
| ''Enterprise''
| Final ''Enterprise'' free flight; First landing on Edwards AFB concrete runway.
|-
| April 12, 1981
| [[Space Shuttle Columbia|''Columbia'']]
| First ''Columbia'' flight, first orbital test flight; [[STS-1]]
|-
| November 11, 1982
| ''Columbia''
| First operational flight of the Space Shuttle, first mission to carry four astronauts; [[STS-5]]
|-
| April 4, 1983
| [[Space Shuttle Challenger|''Challenger'']]
| First ''Challenger'' flight; [[STS-6]]
|-
| August 30, 1984
| [[Space Shuttle Discovery|''Discovery'']]
| First ''Discovery'' flight; [[STS-41-D]]
|-
| October 3, 1985
| [[Space Shuttle Atlantis|''Atlantis'']]
| First ''Atlantis'' flight; [[STS-51-J]]
|-
| January 28, 1986
| ''Challenger''
| [[Space Shuttle Challenger disaster|Disaster starting 73 seconds after launch]]; [[STS-51-L]]; all seven crew members died.
|-
| September 29, 1988
| ''Discovery''
| First post-''Challenger'' mission; [[STS-26]]
|-
| May 4, 1989
| ''Atlantis''
| The first Space Shuttle mission to launch a space probe, [[Magellan probe|Magellan]]; [[STS-30]]
|-
| April 24, 1990
| ''Discovery''
| Launch of the [[Hubble Space Telescope]]; [[STS-31]]
|-
| May 7, 1992
| [[Space Shuttle Endeavour|''Endeavour'']]
| First ''Endeavour'' flight; [[STS-49]]
|-
| November 19, 1996
| ''Columbia''
| Longest Shuttle mission to date at 17 days, 15 hours; [[STS-80]]
|-
| October 11, 2000
| ''Discovery''
| 100th Space Shuttle mission; [[STS-92]]
|-
| February 1, 2003
| ''Columbia''
| [[Space Shuttle Columbia disaster|Disintegrated during re-entry]]; [[STS-107]]; all seven crew members died.
|-
| July 25, 2005
| ''Discovery''
| First post-''Columbia'' mission; [[STS-114]]
|-
| August 28, 2009
| ''Discovery''
| Carried [[Multi-Purpose Logistics Module]] (MPLM) ''Leonardo'' to ISS; [[STS-128]]
|-
! colspan="4" | Planned fleet events
|-
| May 14, 2010
| ''Atlantis''
| Last planned ''Atlantis'' flight; [[STS-132]]
|-
| July 29, 2010
| ''Endeavour''
| Last planned ''Endeavour'' flight; [[STS-134]]<ref>http://www.nasa.gov/missions/highlights/schedule.html</ref>
|-
| September 16, 2010
| ''Discovery''
| Last planned ''Discovery'' flight; last planned flight of the ''Space Shuttle program''; [[STS-133]]
|}
Sources: NASA launch manifest,<ref name="manifest">{{Cite web|url=http://www.nasa.gov/mission_pages/station/structure/iss_manifest.html |title=Consolidated Launch Manifest |accessdate=May 28, 2009 |dateformat=mdy |publisher=NASA}}</ref> NASA Space Shuttle archive<ref name="archive">{{Cite web |url=http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/list_main.html |title=Space Shuttle Mission Archives |accessdate=May 28, 2009|dateformat=mdy|publisher=NASA}}</ref>

===Shuttle disasters===
{{Main|Space Shuttle Challenger disaster|Space Shuttle Columbia disaster}}

On January 28, 1986, the Space Shuttle ''Challenger'' disintegrated 73 seconds after launch due to the failure of the right SRB, killing all seven astronauts on board. The disaster was caused by cold-temperature impairment of the SRB O-rings, a mission critical component. Repeated warnings from design engineers voicing concerns about the lack of evidence of the O-ring's safety when the temperature was below 53&nbsp;°F (12&nbsp;°C) were ignored by NASA managers.<ref>{{cite web|url=http://history.nasa.gov/rogersrep/v1ch6.htm |title="Report of the PRESIDENTIAL COMMISSION on the Space Shuttle Challenger Accident", Chapter VI: An Accident Rooted in History |publisher=History.nasa.gov |date= |accessdate=2009-07-17}}</ref>

In 2003, the Space Shuttle ''Columbia'' disintegrated during re-entry because of damage to heat tiles caused during launch. Ground control engineers made three separate requests for high-resolution images taken by the Department of Defense that would have provided a clearer understanding of the extent of the damage, while NASA's chief thermal protection system (TPS) engineer requested that astronauts on board the ''Columbia'' be allowed to leave the vehicle to inspect the damaged tiles. NASA managers intervened to stop the Department of Defense's assistance and refused the request for the spacewalk,<ref>[http://www.century-of-flight.net/Aviation%20history/space/Columbia%20accident.htm "the Columbia Accident"]. century-of-flight.net</ref> and thus the feasibility of scenarios for astronaut repair or rescue by the Space Shuttle ''Atlantis'' were not considered by NASA management at the time.<ref>{{cite web|url=http://www.nasa.gov/columbia/caib/PDFS/VOL2/D13.PDF |title=D13 - In-Flight Options |format=PDF |date= |accessdate=2009-07-17}}</ref>

==Retirement==
NASA's current plans call for the Space Shuttle to be retired from service in 2010, after nearly 30 years of service. ''Atlantis'' will be the first of NASA's three remaining operational Space Shuttles to be retired as the program winds down.<ref>{{cite web|url=http://www.nasa.gov/missions/highlights/schedule.html |title=NASA - NASA's Shuttle and Rocket Launch Schedule |publisher=Nasa.gov |date= |accessdate=2009-07-17}}</ref> To fill the void left by the Shuttle's retirement, a new spacecraft is being developed to ferry not only passengers and cargo to the ISS but also to travel beyond Earth orbit to the [[Moon]] and [[Mars]].<ref>{{cite web|url=http://www.csa.com/discoveryguides/newshuttle/overview.php |title=The Space Shuttle and Its Replacement |publisher=Csa.com |date= |accessdate=2009-07-17}}</ref> Originally called the [[Crew Exploration Vehicle]], the concept has evolved into the [[Orion (spacecraft)|Orion]] spacecraft and the project named [[Constellation program|Project Constellation]]. However, The Obama Administration has proposed eliminating funds for the Constellation program.<ref>{{cite web|url=http://www.washingtonpost.com/wp-dyn/content/article/2010/01/31/AR2010013101058.html |title=NASA budget for 2011 eliminates funds for manned lunar missions |publisher=Washington Post |date= |accessdate=2010-02-01}}</ref> Until another launch vehicle is ready, crews traveling to and from the [[International Space Station]] will have to do so on board Russian spacecraft or possibly an American commercial spacecraft.

The Shuttle Discovery has already been promised to the [[Smithsonian Institution]]'s [[National Air and Space Museum]], and the Atlantis, Endeavour, and possibly the Enterprise, are planned to be sold to other education institutions or museums for [[United States Dollar|$]]28.8 million.<ref name="shuttle_sale" />

===Commercial replacement vehicles and services===
NASA announced the awarding of contracts for the [[Commercial Orbital Transportation Services|cargo resupply]] of the International Space Station (ISS) to [[SpaceX]] and [[Orbital Sciences Corporation]] on December 23, 2008.<ref>[http://www.nasa.gov/home/hqnews/2008/dec/HQ_C08-069_ISS_Resupply.html "NASA Awards Space Station Commercial Resupply Services Contracts"]. NASA, December 23, 2008.</ref> SpaceX will use its [[Falcon 9]] launch vehicle and [[SpaceX Dragon|Dragon]] spacecraft.<ref>{{cite web|url=http://www.spacex.com/press.php?page=20081223 |title=Space Exploration Technologies Corporation - Press |publisher=Spacex.com |date= |accessdate=2009-07-17}}</ref> Orbital Sciences will use its [[Taurus II]] launch vehicle and [[Cygnus spacecraft]].

==See also==
{{colbegin}}
*[[Criticism of the Space Shuttle program]]
*[[Getaway Special]]
*[[GRiD Compass]] the early laptop carried aboard the shuttle.
*[[Human spaceflight]]
*[[List of human spaceflights]]
*[[List of Space Shuttle missions]]
*[[Space Shuttle design process]]
*[[Orbiter Processing Facility]]
*[[Shuttle Derived Launch Vehicle]]
*[[Shuttle SERV]]
*[[Shuttle Training Aircraft]]
*[[Space accidents and incidents]]
*[[Space exploration]]
*[[Space Shuttle abort modes]]
*[[Space Shuttle crews]]
*[[Space Shuttle program]]
*[[HL-20 Personnel Launch System]]

===Fiction and games===
*[[Space shuttle in popular culture]]

===Physics===
*[[Atmospheric reentry]]
*[[Lifting body]]
*[[Reusable launch system]]
*[[Single-stage-to-orbit]]

===Similar spacecraft===
*[[Buran program]] <small> 1974-1992 </small>
*[[Comparison of heavy lift launch systems]]
*[[DIRECT]], a shuttle-derived vehicle proposed as an alternative for [[Project Constellation]]
*[[X-20 Dynasoar|X-20 Dyna-Soar]] <small> 1957-1963 </small>
*[[EADS Phoenix]]
*[[Hermes (shuttle)|Hermes]] <small> 1975-1992 </small>
*[[HOPE-X]]
*[[Kliper]]
*[[Lockheed Martin X-33]] <small> 1995-2001 </small>
*[[Military space shuttle]]
*[[Orion (spacecraft)|Orion]] ([[Project Constellation]])

{{colend}}

==References==
{{reflist|2}}

==Further reading==
*[http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/stsref-toc.html NSTS 1988 Reference manual]
*[http://science.howstuffworks.com/space-shuttle.htm How The Space Shuttle Works]
*[http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19810022734_1981022734.pdf NASA Space Shuttle News Reference - 1981 (PDF document)]
*[http://science.ksc.nasa.gov/shuttle/resources/orbiters/orbiters.html Orbiter Vehicles]
*[http://ocw.mit.edu/OcwWeb/Aeronautics-and-Astronautics/16-885JFall-2005/LectureNotes/index.htm Lecture Series on the space shuttle] from [[MIT OpenCourseWare]]

==External links==
{{external links}}
{{Commons|Space Shuttle}}
*[http://spaceflight.nasa.gov/shuttle/ NASA Human Spaceflight - Shuttle]: Current status of shuttle missions
*[http://shuttlesource.com Video of current and historical missions (STS-1 thru Current)]
*[[NASA TV]]: View live streaming of launch and mission coverage
*[news:sci.space.shuttle Space Shuttle Newsgroup – sci.space.shuttle]
*[http://www.globalsecurity.org/space/facility/sts-els.htm List of all Shuttle Landing Sites]
*[http://www.srh.noaa.gov/smg/lsitegif.htm Map of Landing Sites]
*Official NASA [http://spaceflight.nasa.gov/realdata/tracking/ Human Space Flight Orbital Tracking] system
*[http://digital.library.unt.edu/govdocs/crs/search.tkl?q=space+shuttle&search_crit=title&search=Search&date1=Anytime&date=Anytime&type=form Congressional Research Service (CRS) Reports regarding the Space Shuttle]
*[http://chandra.harvard.edu/launch/status/weather_criteria2.html Weather criteria for shuttle launch]
*[http://spaceflight.nasa.gov/gallery/images/shuttle/index.html NASA Shuttle Gallery: Newer images, audio, and video of the space shuttle program]
*[http://nix.larc.nasa.gov/search;?b=SC000249 Older images of the space shuttle program]
*[http://video.google.co.uk/videoplay?docid=8147866533180818812 The maiden launch of the space shuttle (Google Video)]
*[http://www.drafts.de/module-Mediashare-slideshow-aid-13-back-1.htm Different details and perspectives from the orbiter (Gallery drafts.de)] (ger.)
*[http://www.exploration-space.com/16-apr-2007-nasa.html 04/16/07: Consolidated Launch Manifest: Space Shuttle Flights and ISS Assembly Sequence.]
*[http://www.space-astronautics.com/29-apr-2007-nasa.html NASA Further Updates Launch Schedule.]
*[http://pages.total.net/~hrothgar/museum/Compass/ GRiD Compass History at Hrothgar's Cool Old Junk Page]
*[http://history.nasa.gov/series95.html NASA History Series Publications] (many of which are on-line)
<!-- *[http://www.applecam.co.uk/space-shuttle/index.htm Space Shuttle Endeavour Pictures at the ISS] dead link?-->
*[http://dsc.discovery.com/tv/nasa/shuttle-timeline/shuttle-timeline.html A timeline slideshow of the space shuttle]'' [[SwitchYard Media for the Discovery Channel]].
*[http://www.fastcompany.com/magazine/06/writestuff.html They Write the Right Stuff] : Software development for the Space Shuttle

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Revision as of 15:54, 8 February 2010

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