Jump to content

Space Shuttle: Difference between revisions

From Wikipedia, the free encyclopedia
Content deleted Content added
Challisrussia (talk | contribs)
No edit summary
clarification: the external tank cannot be re-used in orbit for its original purpose, once it has been jettisoned from the orbiter.
Line 62: Line 62:
At launch, the Space Shuttle consists of the shuttle ''stack'', which includes 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 [[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 the STS (single-stage [[Payload Assist Module]] or two-stage [[Inertial Upper Stage]]). The Space Shuttle is stacked in the [[Vehicle Assembly Building]] and the stack mounted on a mobile launch platform held down by four [[Pyrotechnic fastener|explosive bolts]] on each SRB which are detonated at launch.<ref>{{cite web|title=Solid Rocket Boosters|url=http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/srb.html|publisher=NASA KSC|accessdate=2011-06-30}}</ref>
At launch, the Space Shuttle consists of the shuttle ''stack'', which includes 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 [[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 the STS (single-stage [[Payload Assist Module]] or two-stage [[Inertial Upper Stage]]). The Space Shuttle is stacked in the [[Vehicle Assembly Building]] and the stack mounted on a mobile launch platform held down by four [[Pyrotechnic fastener|explosive bolts]] on each SRB which are detonated at launch.<ref>{{cite web|title=Solid Rocket Boosters|url=http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/srb.html|publisher=NASA KSC|accessdate=2011-06-30}}</ref>


The shuttle stack launches vertically like a conventional rocket. It lifts off under the power of its two SRBs and three [[Space Shuttle main engine|main engines]], which are fueled by liquid hydrogen and liquid oxygen from the external tank. The Space Shuttle has a two-stage ascent. The SRBs provide additional thrust during liftoff and first-stage flight. About two minutes after liftoff, explosive bolts are fired, releasing the SRBs, which then parachute into the ocean, to be retrieved by [[NASA recovery ship|ships]] for refurbishment and reuse. The shuttle orbiter and external tank continue to ascend on an increasingly horizontal flight path under power from its main engines. Upon reaching 17,500&nbsp;mph (7.8&nbsp;km/s), necessary for [[low Earth orbit]], the main engines are shut down. The external tank is then jettisoned to burn up in the atmosphere. It is, however, possible for the external tank to be re-used in orbit.<ref name=etuse/> After jettisoning the external tank, the [[orbital maneuvering system]] (OMS) engines may be used to adjust the orbit.
The shuttle stack launches vertically like a conventional rocket. It lifts off under the power of its two SRBs and three [[Space Shuttle main engine|main engines]], which are fueled by liquid hydrogen and liquid oxygen from the external tank. The Space Shuttle has a two-stage ascent. The SRBs provide additional thrust during liftoff and first-stage flight. About two minutes after liftoff, explosive bolts are fired, releasing the SRBs, which then parachute into the ocean, to be retrieved by [[NASA recovery ship|ships]] for refurbishment and reuse. The shuttle orbiter and external tank continue to ascend on an increasingly horizontal flight path under power from its main engines. Upon reaching 17,500&nbsp;mph (7.8&nbsp;km/s), necessary for [[low Earth orbit]], the main engines are shut down. The external tank is then jettisoned to burn up in the atmosphere. It is, however, possible for the external tank to be re-used (for another purpose) in orbit.<ref name=etuse/> After jettisoning the external tank, the [[orbital maneuvering system]] (OMS) engines may be used to adjust the 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|publisher=NASA|year=1995|author=NASA |archiveurl = http://web.archive.org/web/20071013232332/http://liftoff.msfc.nasa.gov/academy/space/atmosphere.html |archivedate = October 13, 2007}}</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 the capture and return of large payloads back to Earth.
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|publisher=NASA|year=1995|author=NASA |archiveurl = http://web.archive.org/web/20071013232332/http://liftoff.msfc.nasa.gov/academy/space/atmosphere.html |archivedate = October 13, 2007}}</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 the capture and return of large payloads back to Earth.

Revision as of 14:06, 9 July 2011

Template:Two other uses

Space Shuttle
Space Shuttle Discovery launches at the start of STS-120.
FunctionManned orbital launch and reentry
ManufacturerUnited Space Alliance:
Thiokol/Alliant Techsystems (SRBs)
Lockheed Martin/Martin Marietta (ET)
Boeing/Rockwell (orbiter)
Country of originUnited States
Size
Height56.1 m (184.2 ft)
Diameter8.7 m (28.5 ft)
Mass2,030 t (4,470,000 lbm)
Capacity
Payload to LEO24,400 kg (53,600 lb)
Payload to
GTO
3,810 kg (8,390 lbm)
Payload to
Polar orbit
12,700 kg (28,000 lb)
Launch history
StatusActive
Launch sitesLC-39, Kennedy Space Center
SLC-6, Vandenberg AFB (unused)
Total launches135
Success(es)134 successful launches
132 successful re-entries
Failure(s)2:
(launch failure, Challenger); and
(re-entry failure, Columbia)
First flightApril 12, 1981
Type of passengers/cargoTracking and Data Relay Satellites
Spacelab
Great Observatories (including Hubble)
Galileo, Magellan, Ulysses
Mir Docking Module
ISS components
Boosters - Solid Rocket Boosters
No. boosters2
Engines1 solid
Thrust12.5 MN each, sea level liftoff (2,800,000 lbf)
Specific impulse269 s
Burn time124 s
Propellantsolid
First stage - External Tank
Engines3 SSMEs located on Orbiter
Thrust5.45220 MN total, sea level liftoff (1,225,704 lbf)
Specific impulse455 s
Burn time480 s
PropellantLOX/LH2
Second stage Orbiter
Engines2 OME
Thrust53.4 kN combined total vacuum thrust (12,000 lbf)
Specific impulse316 s
Burn time1250 s
PropellantMMH/N2O4

The Space Shuttle is a reusable launch system and orbital spacecraft operated by the U.S. National Aeronautics and Space Administration (NASA) for human spaceflight missions. The system combines 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 is to be retired from service in 2011 after 135 missions;[1] on July 8, 2011, Space Shuttle Atlantis performed that 135th launch - the last launch of the three decade shuttle program.[2] Major missions have included launching numerous satellites and interplanetary probes,[3] conducting space science experiments, and servicing and construction of space stations. Five space-worthy orbiters were built—two were destroyed in accidents and two have been retired, leaving one currently in service.

It has been used for orbital space missions by NASA, the U.S. Department of Defense, the European Space Agency, Japan, and Germany.[4][5] 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.[4][6][7][8][9] In addition, SL-J was partially funded by Japan.[5]

At launch, the Space Shuttle consists of the shuttle stack, which includes a dark orange-colored external tank (ET);[10][11] two white, slender Solid Rocket Boosters (SRBs); and the 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 the STS (single-stage Payload Assist Module or two-stage Inertial Upper Stage). The Space Shuttle is 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.[12]

The shuttle stack launches vertically like a conventional rocket. It lifts off under the power of its two SRBs and three main engines, which are fueled by liquid hydrogen and liquid oxygen from the external tank. The Space Shuttle has a two-stage ascent. The SRBs provide additional thrust during liftoff and first-stage flight. About two minutes after liftoff, explosive bolts are fired, releasing the SRBs, which then parachute into the ocean, to be retrieved by ships for refurbishment and reuse. The shuttle orbiter and external tank continue 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 are shut down. The external tank is then jettisoned to burn up in the atmosphere. It is, however, possible for the external tank to be re-used (for another purpose) in orbit.[13] After jettisoning the external tank, the orbital maneuvering system (OMS) engines may be used to adjust the orbit.

The orbiter carries astronauts and payload such as satellites or space station parts into low Earth orbit, into the Earth's upper atmosphere or thermosphere.[14] 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 22,700 kilograms (50,000 lb), 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 the capture and return of large payloads back to Earth.

When the orbiter's space mission is complete, it fires its OMS thrusters to drop out of orbit and re-enter the lower atmosphere.[14] During descent, the orbiter passes through different layers of the atmosphere and decelerates from hypersonic speed primarily by aerobraking. In the lower atmosphere and landing phase, it is more like a glider but 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, hypersonic flight, and subsonic atmospheric flight. As a result, the orbiter has a relatively high sink rate at low altitudes, and it transitions during re-entry from using RCS thrusters at very high altitudes to flight surfaces in the lower atmosphere.

Early history

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

Though design and construction of the Space Shuttle began in the early 1970s, conceptualization began two decades earlier, before the Apollo program of the 1960s. The concept of a spacecraft returning from space to a horizontal landing began 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 another X-series spaceplane proposal, called the X-20, which was not constructed. 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. One of the responses was for a two-stage design, featuring a large booster and a small orbiter, called the DC-3.

In 1969, President Richard Nixon decided to proceed with Space Shuttle development. 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.[15] Spacelab would provide a multi-disciplinary orbital space laboratory and additional space equipment for the Shuttle.[15]

Description

STS-1 on the launch pad, 1981

The Space Shuttle is the first orbital spacecraft designed for reuse. 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 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).[16] Only the orbiter enters orbit shortly after the tank and boosters are jettisoned. The vehicle is launched vertically like a conventional rocket, and the orbiter glides to a horizontal landing like an airplane, after which it is refurbished for reuse. The SRBs parachute to splashdown in the ocean where they are towed back to shore and refurbished for later shuttle missions.

Six airworthy orbiters were built; the first, Enterprise (OV-101), was not built for orbital space flight, and was used only for testing gliding and landing, followed by Columbia (OV-102), Challenger (OV-099), Discovery (OV-103), Atlantis (OV-104), and Endeavour (OV-105). 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.[17]

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.[18] However, two missions were paid for by Germany, Spacelab D1 and D2 (D for Deutschland) with a payload control center in Oberpfaffenhofen, Germany.[19][20] D1 was the first time that control of a manned STS mission payload was not in U.S. hands.[4]

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, originally built to assemble the Apollo-Saturn V rocket stacks.

Responsibility for the shuttle components is spread among multiple NASA field centers. The Kennedy Space Center is 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 serves as the central point for all shuttle operations, the Marshall Space Flight Center is 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 manages the global tracking network. [22]

Orbiter vehicle

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, control the orbiter during descent and landing.

The orbiter has a large payload bay measuring 15 by 60 feet (4.6 by 18 m) 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 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.[23]

External tank

The main function of the Space Shuttle external tank is to supply the liquid oxygen and hydrogen fuel to the main engines. It is also the backbone of the launch vehicle, providing attachment points for the two Solid Rocket Boosters and the Orbiter. The external tank is the only part of the shuttle system that is not reused. 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).[13][24]

Solid Rocket Boosters

Two solid rocket boosters (SRBs) each provide 12.5 million newtons (2.8 million lbf) of thrust at liftoff,[25] which is 83% of the total thrust needed for liftoff. The SRBs are jettisoned two minutes after launch at a height of about 150,000 feet (46 km), and then deploy parachutes and land in the ocean to be recovered.[26] The SRB cases are made of steel about ½ inch (13 mm) thick.[27] 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.[28]

Orbiter add-ons

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 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.[29] 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.[30]

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.[30] Supported by a modular system of pressurized modules, pallets, and systems, Spacelab missions executed on multidisciplinary science, orbital logistics, international cooperation.[30] Over 29 missions flew on subjects ranging from astronomy, microgravity, radar, and life sciences, to name a few.[30] Spacelab hardware also supported missions such as Hubble (HST) servicing and space station resupply.[30] STS-2 and STS-3 provided testing, and the first full mission was Spacelab-1 (STS-9) launched on November 28, 1983.[30]

Spacelab formally began in 1973, after a meeting in Brussels, Belgium, by European heads of state.[15] Within the decade, Spacelab would go into orbit and provide not only Europe, but also the United States, with an orbital workshop and hardware system.[15] The international cooperation, science, and exploration realized by Spacelab is both the fulfillment of a vision, and a foundation, for what space can do for mankind.[30]

Flight systems

During STS-101, Atlantis was the first shuttle to fly with a glass cockpit. (Composite image)

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 connected 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 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).[31][32]

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 unlikely case of two out of four computers simultaneously failing (a two-two split), one group is picked at random.

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 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 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.

Early shuttle missions, starting in November 1983, took along the GRiD Compass, arguably one of the first laptop computers. The GRiD was given the name SPOC, for Shuttle Portable Onboard Computer. Use on the Shuttle required both hardware and software modifications which were incorporated into later versions of the commercial product. It was used to monitor and display the Shuttle's ground position, path of the next two orbits, show where the shuttle had line of sight communications with ground stations, and determine points for location-specific observations of the Earth. The Compass sold poorly, as it cost at least US$8000, but it offered unmatched performance for its weight and size.[33] NASA was one of its main customers.[34]

Orbiter markings and insignia

The typeface used on the Space Shuttle Orbiter is Helvetica.[35] 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 have been various NASA insignia, the text "United States" and a flag of the United States. Another United States flag appears on the right wing.

Upgrades

The Space Shuttle was initially developed in the 1970s,[36] but 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. 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.

Block II SSME in 2002

The Space Shuttle Main Engines (SSMEs) have had several improvements to enhance reliability and power. This explains phrases such as "Main engines throttling up to 104 percent." This does not mean the engines are being run over a safe limit. The 100 percent figure is the original specified power level. During the lengthy development program, Rocketdyne determined the engine was capable of safe reliable operation at 104 percent of the originally specified thrust. NASA could have rescaled the output number, saying in essence 104 percent is now 100 percent. To clarify this would have required revising much previous documentation and software, so the 104 percent 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 percent, with 106 percent or 109 percent used for mission aborts.

For the first two missions, STS-1 and STS-2, the 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 resulted in an increase in payload capability to orbit.[37] 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 lb) less than the last run of lightweight tanks. As the shuttle is not flown 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 1986 Space Shuttle Challenger disaster.

The three nozzles of the Main Engine cluster with the two Orbital Maneuvering System (OMS) pods, and the vertical stabilizer above.

Several other SRB improvements were planned to improve performance and safety, but never came to be. These culminated in the considerably simpler, lower cost, probably safer and better-performing 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.[38] 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 woodpeckers 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.[39] The delicate nature of the foam insulation has been the cause of damage to the Thermal Protection System, the tile heat shield and heat wrap of the orbiter, during recent launches. NASA remained confident that this damage, while it was the primary cause of the Space Shuttle Columbia disaster on February 1, 2003, would not jeopardize the completion the International Space Station (ISS) in the projected time allotted.

A cargo-only, unmanned variant of the shuttle was 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. Another proposal was to convert the payload bay into a passenger area, with proposals ranging from 30 to 74 seats, three days in orbit, and 1.5 million USD a seat.[40]

On the first four shuttle missions, astronauts wore modified US 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 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 resembled the Gemini space suit in design, but retained the orange color of the Launch-Entry Suit.

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

Space Shuttle orbiter illustration
Space Shuttle drawing
Space Shuttle wing cutaway
Space Shuttle Orbiter and Soyuz-TM (drawn to scale).

Orbiter specifications[41] (for Endeavour, OV-105)

  • Length: 122.17 ft (37.237 m)
  • Wingspan: 78.06 ft (23.79 m)
  • Height: 58.58 ft (17.86 m)
  • Empty weight: 172,000 lb (78,000 kg)[42]
  • Gross liftoff weight: 240,000 lb (110,000 kg)
  • Maximum landing weight: 230,000 lb (100,000 kg)
  • Maximum payload: 55,250 lb (25,060 kg)
  • Payload to LEO: 53,600 lb (24,310 kg)
  • Payload to LEO (ISS):
  • Payload to GTO: 8,390 lb (3,806 kg)
  • Payload to Polar Orbit: 28,000 lb (12,700 kg)
  • Payload bay dimensions: 15 by 59 ft (4.6 by 18 m)
  • Operational altitude: 100 to 520 nmi (190 to 960 km; 120 to 600 mi)
  • Speed: 7,743 m/s (27,870 km/h; 17,320 mph)
  • Crossrange: 1,085 nmi (2,009 km; 1,249 mi)
  • First Stage (SSME with external tank)
    • Main engines: Three Rocketdyne Block II SSMEs, each with a sea level thrust of 393,800 lbf (1.752 MN) at 104% power
    • Thrust (at liftoff, sea level, 104% power, all 3 engines): 1,181,400 lbf (5.255 MN)
    • Specific impulse: 455 s
    • Burn time: 480 s
    • Fuel: Liquid Oxygen/Liquid Hydrogen
  • Second Stage
    • Engines: 2 Orbital Maneuvering Engines
    • Thrust: 53.4 kN (12,000 lbf) combined total vacuum thrust
    • Specific impulse: 316 s
    • Burn time: 1250 s
    • Fuel: MMH/N2O4
  • 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, pilot, several mission specialists, 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: 46.9 m (154 ft)
  • Diameter: 8.4 m (28 ft)
  • Propellant volume: 2,025 m3 (534,900 US gal)
  • Empty weight: 26,535 kg (58,500 lb)
  • Gross liftoff weight: 756,000 kg (1,670,000 lb)

Solid Rocket Booster specifications

  • Length: 45.46 m (149 ft)[43]
  • Diameter: 3.71 m (12.2 ft)[43]
  • Empty weight (per booster): 68,000 kg (150,000 lb)[43]
  • Gross liftoff weight (per booster): 571,000 kg (1,260,000 lb)[44]
  • Thrust (at liftoff, sea level, per booster): 12.5 MN (2,800,000 lbf)[25]
  • Specific impulse: 269 s
  • Burn time: 124 s

System Stack specifications

  • Height: 56 m (180 ft)
  • Gross liftoff weight: 2,000,000 kg (4,400,000 lb)
  • Total liftoff thrust: 30.16 MN (6,780,000 lbf)

Mission profile

STS mission profile
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, which necessitates having a Shuttle on standby for a possible rescue mission.
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.
Multicolored afterglow of the STS-131 launch
SSLV at Mach 2.46 and 66,000 ft (20,000 m). 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 codes.

Launch

All Space Shuttle missions are launched from Kennedy Space Center (KSC). The weather criteria used for launch include, but are not limited to: precipitation, temperatures, cloud cover, lightning forecast, wind, and humidity.[45] 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 grounded. Like most jet airliners, the shuttle is mainly constructed of conductive aluminum, which would normally shield and protect the internal systems. However, upon liftoff 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.[46] 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.[45][47] While the shuttle might safely endure a lightning strike, a similar strike caused problems on Apollo 12, so for safety NASA chooses not to launch the shuttle if lightning is possible (NPR8715.5).

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.[48]

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 350,000 US gallons (1,300 m3) of water to protect the Orbiter from damage by acoustical energy and rocket exhaust reflected from the flame trench and MLP during liftoff.http://www.nasa.gov/mission_pages/shuttle/launch/sound-suppression-system.html[49]

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.

The three 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 percent of their rated performance to complete the final gimbal of the main engine nozzles to liftoff configuration.[50] When the SSMEs start, water from the sound suppression system flashes into a large volume of steam that shoots southward. All three SSMEs must reach the required 100 percent thrust within three seconds, otherwise the onboard computers will initiate an RSLS abort. If the onboard computers verify normal thrust buildup, at T minus 0 seconds, the 8 pyrotechnic nuts holding the vehicle to the pad are detonated and the SRBs are ignited. At this point the vehicle is committed to liftoff, as the SRBs cannot be turned off once ignited.[51] 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 (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 Challenger disaster, there were extensive upgrades to the abort modes.

After the main engines start, but while the solid rocket boosters are still bolted 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. The Johnson Space Center's Mission Control Center assumes control of the flight once the SRBs have cleared the launch tower.

Shortly after clearing the tower, the Shuttle begins a combined roll, pitch and yaw maneuver that positions the orbiter head down, with wings level and aligned with the launch pad. The Shuttle flies upside down during the ascent phase. This orientation allows a trim angle of attack that is favorable for aerodynamic loads during the region of high dynamic pressure, resulting in a net positive load factor, as well as providing the flight crew with use of the ground as a visual reference. 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 380 kilometers (236 mi) altitude of the International Space Station is 7.68 kilometers per second 27,650 km/h (17,180 mph), 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.

Around a point called Max Q, where the aerodynamic forces are at their maximum, the main engines are temporarily throttled back to 72 percent to avoid 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+70 seconds, the main engines throttle up to their maximum cruise thrust of 104% rated thrust.

At T+126 seconds after launch, explosive bolts 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 main engines. The vehicle at that point in the flight has a thrust-to-weight ratio of less than one– 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.

The vehicle continues to climb and takes on a somewhat nose-up angle to the horizon– 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's direct communication links with the ground begin to fade, at which point it rolls heads up to reroute its communication links to the Tracking and Data Relay Satellite system.

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 (29.34 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.[41] 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.

Contraves-Goerz Kineto Tracking Mount used to image the space shuttle during launch ascent

The shuttle is monitored throughout its ascent for short range tracking (10 seconds before liftoff through 57 seconds after), medium range (7 seconds before liftoff through 110 seconds after) and long range (7 seconds before liftoff through 165 seconds after). Short range cameras include 22 16mm cameras on the Mobile Launch Platform and 8 16mm on the Fixed Service Structure, 4 high speed fixed cameras located on the perimeter of the launch complex plus and additional 42 fixed cameras with 16mm motion picture film. Medium range cameras include remotely operated tracking cameras at the launch complex plus 6 sites along the immediate coast north and south of the launch pad, each with 800mm lens and high speed cameras running 100 feet per second. These cameras run for only 4–10 seconds due to limitations in the amount of film available. Long range cameras include those mounted on the External Tank, SRBs and orbiter itself which stream live video back to the ground providing valuable information about any debris falling during ascent. Long range tracking cameras with 400-inch film and 200-inch video lenses are operated by a photographer at Playalinda Beach as well as 9 other sites from 38 miles north at the Ponce Inlet to 23 miles south to Patrick Air Force Base (PAFB) and additional mobile optical tracking camera is stationed on Merrit Island during launches. A total of 10 HD cameras are used both for ascent information for engineers and broadcast feeds to networks such as NASA TV and HDNet The number of cameras significantly increased and numerous existing cameras were upgraded at the recommendation of the Columbia Accident Investigation Board to provide better information about debris during launch. Debris is also tracked using a pair of Weibel Continuous Pulse Doppler X-band radars, one onboard the SRB recovery ship MV Liberty Star positioned north east of the launch pad and on a ship positioned south of the launch pad. Additionally, during the first 2 flights following the loss of Columbia and her crew, a pair of NASA WB-57 reconnaissance aircraft equipped with HD Video and Infrared flew at 60,000 feet (18,000 m) to provide additional views of the launch ascent.[52] Kennedy Space Center also invested nearly $3 million in improvements to the digital video analysis systems in support of debris tracking.[53]

In orbit

Atlantis and Harmony—spring 2010

Once in orbit, the Shuttle usually flies at an altitude of 200 miles (321.9 km), and occasionally as high as 400 miles.[54] 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

Almost the entire Space Shuttle re-entry procedure, 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 200 mph (322 km/h). 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 is 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 400,000 ft (120 km), at around Mach 25, 8,200 m/s (30,000 km/h; 18,000 mph). The vehicle is controlled by a combination of 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.

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.[55]

In the lower atmosphere, the orbiter flies much like a conventional glider, except for a much higher descent rate, over 50 m/s (180 km/h; 110 mph)(9800fpm). 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.

Final approach and landing phase

STS-127, Space Shuttle Endeavour landing video (2009)

When the approach and landing phase begins, the orbiter is at a 3,000 m (9,800 ft) altitude, 12 km (7.5 mi) from the runway. The pilots apply aerodynamic braking to help slow down the vehicle. The orbiter's speed is reduced from 682 to 346 km/h (424 to 215 mph), approximately, at touch-down (compared to 260 km/h (160 mph) for a jet airliner). The landing gear is deployed while the Orbiter is flying at 430 km/h (270 mph). To assist the speed brakes, a 12 m (39 ft) drag chute is deployed either after main gear or nose gear touchdown (depending on selected chute deploy mode) at about 343 km/h (213 mph). The chute is jettisoned once the orbiter slows to 110 km/h (68.4 mph).

Media related to Landings of space shuttles at Wikimedia Commons

Post-landing processing

Discovery after landing on Earth for crew disembarkment

After landing, the vehicle stands on the runway for several minutes for the orbiter to cool. Teams at the front and rear of the orbiter test for presence of hydrogen, hydrazine, monomethylhydrazine, nitrogen tetroxide and ammonia (fuels and by products of the control and the orbiter's three APUs). If hydrogen is detected, an emergency is declared, the orbiter powered down and teams evacuate the area. A convoy of 25 specially-designed vehicles and 150 trained engineers and technicians approach the orbiter. Purge and vent lines are attached to remove toxic gasses from fuel lines and the cargo bay about 45–60 minutes after landing. A flight surgeon boards the orbiter for initial medical checks of the crew before disembarking. Once the crew has left the orbiter, responsibility for the vehicle is handed from the Johnson Space Center back to the Kennedy Space Center[56]

If the mission ended at Edwards Air Force Base in California, White Sands Space Harbor in New Mexico, or any of the runways the orbiter might use in an emergency, the orbiter will be loaded atop the Shuttle Carrier Aircraft, a modified 747, for transport back to the Kennedy Space Center, landing at the Shuttle Landing Facility. Once at the Shuttle Landing Facility, the orbiter is then towed 2 miles (3.2 km) along a tow-way and access roads normally used by tour busses and KSC employees to the Orbiter Processing Facility where it begins a months-long preparation process for the next mission.[56]

Landing sites

NASA prefers Space Shuttle landings to be at Kennedy Space Center.[57] 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 alternative landing sites that have never been used.[58][59]

Risk contributors

Discovery at ISS in 2011 (STS-133)

An example of technical risk analysis for a STS mission is SPRA iteration 3.1 top risk contributors for STS-133:[60][61]

  1. Micro-Meteoroid Orbital Debris (MMOD) strikes
  2. Space Shuttle Main Engine (SSME)-induced or SSME catastrophic failure
  3. Ascent debris strikes to TPS leading to LOCV on orbit or entry
  4. Crew error during entry
  5. RSRM-induced RSRM catastrophic failure (RSRM are the Solid Rocket Boosters)
  6. COPV failure (COPV are tanks inside the orbiter that hold gas at high pressure)

An internal NASA risk assessment study (conducted by the Shuttle Program Safety and Mission Assurance Office at Johnson Space Center) released in late 2010 or early 2011 concluded that the agency had seriously underestimated the level of risk involved in operating the shuttle. The report assessed that there was a 1 in 9 chance of a catastrophic disaster during the first nine flights of the shuttle but that safety improvements had later improved the risk ratio to 1 in 100.[62]

Fleet history

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).
Atlantis lifts off from Launch Pad 39A at NASA's Kennedy Space Center in Florida on the STS-132 mission to the International Space Station at 2:20 pm EDT on May 14, 2010. This was one of the last scheduled flights for Atlantis before it is retired.

Below is a list of major events in the Space Shuttle orbiter fleet.

Space Shuttle major events
Date Orbiter Major event / remarks
February 18, 1977 Enterprise First flight; Attached to Shuttle Carrier Aircraft throughout flight.
August 12, 1977 Enterprise First free flight; Tailcone on; lakebed landing.
October 26, 1977 Enterprise Final Enterprise free flight; First landing on Edwards AFB concrete runway.
April 12, 1981 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 Challenger First Challenger flight; STS-6
August 30, 1984 Discovery First Discovery flight; STS-41-D
October 3, 1985 Atlantis First Atlantis flight; STS-51-J
January 28, 1986 Challenger 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; STS-30
April 24, 1990 Discovery Launch of the Hubble Space Telescope; STS-31
May 7, 1992 Endeavour First Endeavour flight; STS-49
November 19, 1996 Columbia Longest Shuttle mission at 17 days, 15 hours; STS-80
December 4, 1998 Endeavour First ISS mission; STS-88
February 1, 2003 Columbia Disintegrated during re-entry; STS-107; all seven crew members died.
July 25, 2005 Discovery First post-Columbia mission; STS-114
February 24, 2011 Discovery Last Discovery flight; STS-133
May 16, 2011 Endeavour Last Endeavour mission; STS-134[63][64]
July 8, 2011 Atlantis Last Atlantis flight and last Space Shuttle flight; STS-135

Sources: NASA launch manifest,[65] NASA Space Shuttle archive[66]

Shuttle disasters

On January 28, 1986, 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 low-temperature impairment of an O-ring, a mission critical seal used between segments of the SRB casing. The failure of a lower O-ring seal allowed hot combustion gases to escape from between the booster sections and burn through the adjacent external tank, causing it to disintegrate. Repeated warnings from design engineers voicing concerns about the lack of evidence of the O-rings' safety when the temperature was below 53 °F (12 °C) had been ignored by NASA managers.[67]

On February 1, 2003, Columbia disintegrated during re-entry, killing its crew of seven, because of damage to the carbon-carbon leading edge of the wing caused during launch. Ground control engineers had made three separate requests for high-resolution images taken by the Department of Defense that would have provided an understanding of the extent of the damage, while NASA's chief thermal protection system (TPS) engineer requested that astronauts on board Columbia be allowed to leave the vehicle to inspect the damage. NASA managers intervened to stop the Department of Defense's assistance and refused the request for the spacewalk,[68] and thus the feasibility of scenarios for astronaut repair or rescue by Atlantis were not considered by NASA management at the time.[69]

Planned retirement

Space Shuttle Program commemorative patch

NASA's current plans call for the Space Shuttle to be retired from service in 2011, after 30 years of service. Under the current plans, Discovery will be the first of NASA's three remaining operational Space Shuttles to be retired as the program winds down.[70] Michael Suffredini of the ISS program has said that one additional trip will be needed in 2011 to deliver parts to the International Space Station.[71] The Space Shuttle was originally to be retired in late 2010, but has been extended until July 2011 according to the NASA launch and mission schedule. One of the smallest shuttle crews in NASA history, composed of just four astronauts—Christopher Ferguson, Douglas Hurley, Rex Walheim and Sandra Magnusare[72]—are conducting the 135th and last space shuttle mission on board Atlantis, which successfully launched on July 8, 2011.

Locations of retired orbiters

The three remaining space-worthy orbiters are planned to be transferred to education institutions or museums at the conclusion of the space shuttle program. Each museum or institution is responsible for covering the US$28.8 million cost of preparing and transporting each vehicle for display. Twenty museums have submitted proposals for displaying one of the retired orbiters including NASA visitors centers as well as aviation and science museums around the country.[73]

On April 12, 2011, NASA announced selection of locations for the remaining Shuttle orbiters:[74][75]

Distribution of other hardware

Flight and mid-deck training hardware from the Johnson Spaceflight Center will go to the National Air and Space Museum and the National Museum of the U.S. Air Force. The full fuselage mockup, which includes the payload bay and aft section but no wings, is to go to the Museum of Flight in Seattle. Mission Simulation and Training Facility's fixed simulator will go to the Adler Planetarium in Chicago, and the motion simulator will go to Texas A&M's Aerospace Engineering Department in College Station, Texas. Other simulators used in shuttle astronaut training will go to the Wings of Dreams Aviation Museum in Starke, Florida and the Virginia Air and Space Center in Hampton, Virginia.[73]

NASA is also making Space Shuttle thermal protection system tiles available to schools and universities for $23.40 each.[76] About 7,000 tiles are available on a first-come, first-served basis, but limited to one each per institution.[76]

Space Shuttle successors and legacy

Until another US launch vehicle is ready, crews will travel to and from the International Space Station aboard Russian Soyuz spacecraft or possibly a future American commercial spacecraft. A planned successor to STS was the "Shuttle II" during the 1980s and 1990s, and later the Constellation program during 2004–2010 period. CSTS was a proposal to continue to operate STS commercially, after NASA.[77]

In culture

Space Shuttle program insignia

Space Shuttles have featured in numerous works of fiction. Early examples include the 1979 James Bond film, Moonraker, where shuttles played a major role well before any were actually launched, Activision videogame Space Shuttle: A Journey into Space (1982) and G. Harry Stine's novel Shuttle Down (1981). In the 1986 film SpaceCamp, Atlantis accidentally launched into space with a group of U.S. Space Camp participants as its crew. The 1998 film Armageddon portrayed a combined crew of offshore oil rig workers and US military staff who pilot two modified shuttles to avert the destruction of Earth by an asteroid. Retired American test pilots visited a Russian satellite in the Clint Eastwood adventure film Space Cowboys (2000). This was followed by the 2004 Bollywood movie Swades, where a space shuttle was used to launch a special rainfall monitoring satellite. The movie was filmed at Kennedy Space Center in the year following the Columbia disaster that had taken the life of KC Chawla, the first woman of Indian origin in space. On television, the 1996 drama The Cape portrayed the lives of a group of NASA astronauts as they prepared for and flew shuttle missions. Odyssey 5 was a short lived sci-fi series that featured the crew of a space shuttle as the last survivors of a disaster that destroyed Earth.

The Space Shuttle has also been the subject of toys and models; for example, a large Lego Space Shuttle model was constructed by visitors at Kennedy Space Center.[78]

U.S. postage commemorations

The U.S. Postal Service has released several postage issues that depict the Space Shuttle. The first such stamps were issued in 1981, and are on display at the National Postal Museum.[79]

See also

References

  1. ^ Jim Abrams (September 29, 2010). "NASA bill passed by Congress would allow for one additional shuttle flight in 2011". Associated Press. Retrieved September 30, 2010.
  2. ^ "Space Shuttle Atlantis Lifts Off". July 9, 2011.
  3. ^ "7 cool things you didn't know about Atlantis".
  4. ^ a b c Interavia (1985), Volume 40, p. 1170 Google Books Quote: "This is the first time that control of a payload aboard a manned Shuttle has been in non-US hands. The D1 mission has been financed entirely by the German Ministry of Research and Technology. .."
  5. ^ a b Life into Space (1995/2000) – Volume 2, Chapter 4, Page: Spacelab-J (SL-J) Payload. NASA Life into Space.
  6. ^ "Columbia Spacelab D2 – STS-55". Damec.dk. Retrieved December 4, 2010.
  7. ^ ESA – Spacelab D1 mission – 25 years ago (October 26, 2010)(accessed December 4, 2010)
  8. ^ Tim Furniss – A history of space exploration and its future (2003) – Page 89 (Google Books accessed December 4, 2010)
  9. ^ Reginald Turnill – Jane's spaceflight directory (1986) – Page 139 (Google Books Quote, "SM 22: the 1st German-funded Spacelab mission made use of the ESA Space Sled.")
  10. ^ "NASA Takes Delivery of 100th Space Shuttle External Tank". NASA, August 16, 1999. Quote: "...orange spray-on foam used to insulate...."
  11. ^ "Media Invited To See Shuttle External Fuel Tank Ship From Michoud". NASA, December 28, 2004. Quote: "The gigantic, rust-colored external tank..."
  12. ^ "Solid Rocket Boosters". NASA KSC. Retrieved June 30, 2011.
  13. ^ a b NASA-CR-195281, "Utilization of the external tanks of the space transportation system". NASA, August 23–27, 1982.
  14. ^ a b NASA (1995). "Earth's Atmosphere". NASA. Archived from the original on October 13, 2007. Retrieved October 25, 2007.
  15. ^ a b c d ESA – N° 10-1998: 25 years of Spacelab – Go for Space Station
  16. ^ Shuttle Basics. NASA.
  17. ^ "NASA – Space Shuttle and International Space Station". Nasa.gov. Retrieved August 7, 2010.
  18. ^ 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.
  19. ^ "Columbia Spacelab D2 – STS-55". Damec.dk. Retrieved August 7, 2010.
  20. ^ [1] [dead link]
  21. ^ "Sound Suppression Water System Test". NASA. Retrieved June 30, 2011.
  22. ^ NASA CENTERS AND RESPONSIBILITIES
  23. ^ "Orbiter Vehicles". NASA Kennedy Space Center. Retrieved October 11, 2009.
  24. ^ STS External Tank Station. astronautix.com
  25. ^ a b Columbia Accident Investigation Board Report, Vol II, Appendix D.7. NASA, October 2003.
  26. ^ "NASA Space Shuttle Columbia Launch".[dead link]
  27. ^ NASA. "Report of the Presidential Commission on the Space Shuttle Challenger Accident". NASA. Retrieved June 30, 2011.
  28. ^ NASA Ares I First Stage Motor to be Tested August 25. NASA, July 20, 2009.
  29. ^ Gunter's Space Page – TOS-21H
  30. ^ a b c d e f g "Spacelab joined diverse scientists and disciplines on 28 Shuttle missions". NASA. March 15, 1999. Retrieved February 11, 2011.
  31. ^ Ferguson, Roscoe C. "Implementing Space Shuttle Data Processing System Concepts in Programmable Logic Devices". NASA Office of Logic Design. Retrieved August 27, 2006. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  32. ^ IBM. "IBM and the Space Shuttle". IBM. Retrieved August 27, 2006.
  33. ^ The Computer History Museum (2006). "Pioneering the Laptop:Engineering the GRiD Compass". The Computer History Museum. Retrieved October 25, 2007.
  34. ^ NASA (1985). "Portable Compute" (PDF). NASA. Retrieved June 23, 2010.
  35. ^ Helvetica (Documentary). September 12, 2007.
  36. ^ a b Dunn, Marcia (January 15, 2010). "Recession Special: NASA Cuts Space Shuttle Price". ABC News. Retrieved January 15, 2010.
  37. ^ Aerospaceweb.org (2006). "Space Shuttle External Tank Foam Insulation". Aerospaceweb.org. Retrieved October 25, 2007.
  38. ^ Encyclopedia Astronautica. "Shuttle". Encyclopedia Astronautica.[dead link]
  39. ^ Jim Dumoulin. "Woodpeckers damage STS-70 External Tank". NASA. Retrieved August 27, 2006.
  40. ^ L David, R Citron, T Rogers & C D Walker, April 25–28, 1985, "The Space Tourist", AAS 85-771 to −774. Proceedings of the Fourth Annual L5 Space Development Conference held April 25–28, 1985, in Washington, D.C..
  41. ^ a b Jenkins, Dennis R. (2007). Space Shuttle: The History of the National Space Transportation System. Voyageur Press. ISBN 0963397451.
  42. ^ "John F. Kennedy Space Center – Space Shuttle Endeavour". Pao.ksc.nasa.gov. Retrieved June 17, 2009.
  43. ^ a b c Jenkins, Dennis R. (2002). Space Shuttle: The History of the National Space Transportation System (Third ed.). Voyageur Press. ISBN 0-9633974-5-1.
  44. ^ Space Shuttle Propulsion Systems, p. 153. NASA, June 26, 1990.
  45. ^ a b "SPACE SHUTTLE WEATHER LAUNCH COMMIT CRITERIA AND KSC END OF MISSION WEATHER LANDING CRITERIA". KSC Release No. 39-99. NASA Kennedy Space Center. Retrieved July 6, 2009.
  46. ^ Weather at About.com. What is the Anvil Rule for Thunderstorms?[dead link]. Retrieved: June 10, 2008.
  47. ^ NASA Launch Blog. [2]. Retrieved: June 10, 2008.
  48. ^ Bergin, Chris (February 19, 2007). "NASA solves YERO problem for shuttle". Archived from the original on April 18, 2008. Retrieved December 22, 2007.
  49. ^ National Aeronautics and Space Administration. "Sound Suppression Water System" Revised August 28, 2000. Retrieved July 9, 2006.
  50. ^ National Aeronautics and Space Administration. "NASA – Countdown 101". Retrieved: July 10, 2008.
  51. ^ "HSF – The Shuttle". Spaceflight.nasa.gov. Retrieved July 17, 2009.
  52. ^ "Shuttle launch imagery from land, air and water" (PDF).
  53. ^ New Eyes for Shuttle Launches
  54. ^ Space Today Online - Answers To Your Questions
  55. ^ http://klabs.org/DEI/Processor/shuttle/shuttle_tech_conf/1985008580.pdf
  56. ^ a b "From Landing to Launch Orbiter Processing" (PDF). NASA Public Affairs Office. Retrieved June 30, 2011.
  57. ^ NASA - Roster of Runways Ready to Bring a Shuttle Home
  58. ^ Global Security. "Space Shuttle Emergency Landing Sites". GlobalSecurity.org. Retrieved August 3, 2007.
  59. ^ US Northern Command. "DOD Support to manned space operations for STS-119". Retrieved June 30, 2011.
  60. ^ Chris Gebhardt. "NASA Reviews COPV Reliability Concerns for Final Program Flights". NASASpaceflight.com. Retrieved December 14, 2010.
  61. ^ Hamlin, et al. 2009 Space Shuttle Probabilistic Risk Assessment Overview (.pdf). NASA.
  62. ^ Florida Today, "Report says NASA underestimated shuttle dangers", Military Times, 13 February 2011; retrieved February 15, 2011.
  63. ^ "NASA – NASA's Shuttle and Rocket Launch Schedule". Nasa.gov. July 27, 2010. Retrieved August 7, 2010.
  64. ^ "NASA Updates Shuttle Target Launch Dates For Final Two Flights". NASA. Retrieved July 3, 2010.
  65. ^ "Consolidated Launch Manifest". NASA. Retrieved May 28, 2009.
  66. ^ "Space Shuttle Mission Archives". NASA. Retrieved May 28, 2009.
  67. ^ ""Report of the PRESIDENTIAL COMMISSION on the Space Shuttle Challenger Accident", Chapter VI: An Accident Rooted in History". History.nasa.gov. Retrieved July 17, 2009.
  68. ^ "the Columbia Accident". century-of-flight.net
  69. ^ "D13 – In-Flight Options" (PDF). Retrieved July 17, 2009.
  70. ^ "NASA – NASA's Shuttle and Rocket Launch Schedule". Nasa.gov. Retrieved July 17, 2009.
  71. ^ John Pike (May 13, 2010). "Space Shuttle may continue through next year – Roscosmos". Globalsecurity.org. Retrieved August 7, 2010.
  72. ^ "Rare Four-Member Crew to Fly Final Shuttle". FoxNews.com, July 3, 2011. Retrieved: July 4, 2011
  73. ^ a b "Photo Gallery: How to display a retired space shuttle". Collect Space. November 1, 2010.
  74. ^ NASA (April 12, 2011). "NASA Announces New Homes for Space Shuttle Orbiters After Retirement". NASA. Retrieved April 12, 2011.
  75. ^ McGeehan, Patrick (April 12, 2011). "Space Shuttle to Land in Manhattan". The New York Times. Retrieved April 12, 2011.
  76. ^ a b "NASA offers space shuttle tiles to school and universities". Chanel 13 News, December 1, 2010.
  77. ^ Rob Coppinger – "NASA weighs plan to keep space shuttle until 2017" (2/3/2011) – MSNBC
  78. ^ Cherie D. Abbey, Kevin Hillstrom – "Biography Today Annual Cumulation 2004: Profiles Of People Of ...: Volume 13; Volume 2004" (2004), Page 55, Quote:"she went to the Kennedy Space Center in Florida, where she helped visitors build the world's largest Lego space shuttle"
  79. ^ Space Achievement Issue. Smithsonian, National Postal Museum

Further reading

NASA
Non-NASA

Template:Link GA Template:Link FA Template:Link FA Template:Link FA