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This article is about the NASA Space Shuttle program. For the shuttle itself, see Space Shuttle. For information on the Soviet space shuttle, see the article Shuttle Buran.

NASA's Space Shuttle, officially called Space Transportation System (STS), is the United States government's current manned launch vehicle. The winged shuttle orbiter is launched vertically, usually carrying five to seven astronauts (although eight have been carried) and up to 50,000 lb (22,700 kg) of payload into low earth orbit. When its mission is complete, it fires its maneuvering thrusters to drop out of orbit and re-enters the earth's atmosphere. During the descent and landing, the shuttle orbiter acts as a glider and makes a completely unpowered landing.

The Shuttle is the first orbital spacecraft designed for partial reusability. It is also so far the only winged manned spacecraft to achieve orbit and land. It carries large payloads to various orbits, 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, but this capacity has not been used often. However, it has been used to return large payloads from the ISS to earth, as the Russian Soyuz spacecraft has limited capacity for return payloads. Each Shuttle was designed for a projected lifespan of 100 launches or 10 years' operational life.

The program started in the late 1960s and has dominated NASA's manned operations since the mid-1970s. According to the Vision for Space Exploration, use of the Space Shuttle will be focused on completing assembly of the ISS in 2010 (more specifically, the construction completion of the ISS), after which it will be replaced by the Crew Exploration Vehicle (CEV).^{[citation needed]}

1 Conception
2 Development
3 Orbiters produced
4 Shuttle applications
5 Flight statistics
6 Accidents
7 Current status
8 Costs
9 Criticism
10 Terrestrial transportation vehicles
11 See also
12 Notes
13 Further reading
14 External links

[edit] Conception

The Space Shuttle Columbia seconds after engine ignition, April 12, 1981 (NASA). This was one of only two missions that had a painted external tank (tallest section that's shown in white).

Even before the Apollo moon landing in 1969, in October 1968 NASA began early studies of space shuttle designs. The early studies were denoted "Phase A", and in June 1970, "Phase B", which were more detailed and specific.

In 1969 President Richard Nixon formed the Space Task Group, chaired by vice president Spiro T. Agnew. They evaluated the shuttle studies to date, and recommended a national space strategy including building a space shuttle.^[1]

In October 1969, at a Space Shuttle symposium held in Washington, George Mueller (NASA deputy administrator) presented opening remarks: [1] "The goal we have set for ourselves is the reduction of the present costs of operating in space from the current figure of $1,000 a pound for a payload delivered in orbit by the Saturn V, down to a level of somewhere between $20 and $50 a pound. By so doing we can open up a whole new era of space exploration. Therefore, the challenge before this symposium and before all of us in the Air Force and NASA in the weeks and months ahead is to be sure that we can implement a system that is capable of doing just that. Let me outline three areas which, in my view, are critical to the achievement of these objectives.

One is the development of an engine that will provide sufficient specific impulse, with adequate margin to propel its own weight and the desired payload.

A second technical problem is the development of the reentry heat shield, so that we can reuse that heat shield time after time with minimal refurbishment and testing.

The third general critical development area is a checkout and control system which provides autonomous operation by the crew without major support from the ground and which will allow low cost of maintenance and repair.

Of the three, the latter may be a greater challenge than the first two."

The 1972 NASA/GAO REPORT TO THE CONGRESS, Cost-Benefit Analysis Used In Support Of The Space Shuttle Program[2] states: NASA has proposed that a space shuttle be developed for U.S. Space Transportation needs for NASA, the Department of Defense (DOD), and other users in the 1980's.The primary objective of the Space Shuttle Program is to provide a new space transportation capability that will:

(1) reduce substantially the cost of space operations and

(2) provide a future capability designed to support a wide range of scientific, defense, and commercial uses.

[edit] Development

During early shuttle development there was great debate about the optimal shuttle design that best balanced capability, development cost and operating cost. Ultimately the current design was chosen, using a reusable winged orbiter, solid rocket boosters, and expendable external tank.^[1]

The Shuttle program was formally launched on January 5, 1972, when President Nixon announced that NASA would proceed with the development of a reusable Space Shuttle system.^[1] The final design was less costly to build and less technically ambitious than earlier fully reusable designs.

The prime contractor for the program was North American Aviation (later Rockwell International), the same company responsible for the Apollo Command/Service Module. The contractor for the Space Shuttle Solid Rocket Boosters was Morton Thiokol (now part of Alliant Techsystems), for the external tank, Martin Marietta (now Lockheed Martin), and for the Space shuttle main engines, Rocketdyne.^[1]

The first complete orbiter was originally named Constitution, but a massive write-in campaign from fans of the Star Trek television series convinced the White House to change the name to Enterprise.^[2] Amid great fanfare, the Enterprise was rolled out on September 17, 1976, and later conducted a successful series of glide-approach and landing tests that were the first real validation of the design.

The first fully functional Shuttle Orbiter was the Columbia, built in Palmdale, California. It was delivered to Kennedy Space Center on March 25, 1979, and was first launched on April 12, 1981—the 20th anniversary of Yuri Gagarin's space flight—with a crew of two. Challenger was delivered to KSC in July 1982, Discovery in November 1983, and Atlantis in April 1985. Challenger was destroyed when it disintegrated during ascent due to O-Ring failure on the right SRB on January 28, 1986, with the loss of all seven astronauts on board. Endeavour was built to replace Challenger (using spare parts originally intended for the other Orbiters) and delivered in May 1991; it was first launched a year later. Seventeen years after Challenger, Columbia was lost, with all seven crew members, during reentry on February 1, 2003, and has not been replaced. Out of five functional shuttle orbiters only three remain for use.

[edit] Orbiters produced

Shuttle launch profiles. From left to right: Columbia, Challenger, Discovery, Atlantis and Endeavour.

Individual Orbiters are both named, in a manner similar to ships, and numbered, using the NASA Orbiter Vehicle Designation system. While all Orbiters are externally very similar, they have minor internal differences; new equipment is fitted on a rotating basis as they are maintained, and the newer Orbiters tend to be structurally lighter.

Test Articles
Number	Name	Notes
OV-098 (honorary)	Pathfinder	Orbiter Simulator for moving and handling tests
MPTA-098	N/A	Testbed for propulsion and fuel delivery systems
STA-099	N/A	Structural test article used for stress and thermal testing, later became Challenger
Orbiters
Number	Name	Notes
OV-099	Challenger	Destroyed after liftoff - January 28, 1986
OV-101	Enterprise	Used for approach and landing tests, not suitable for spaceflight
OV-102	Columbia	Destroyed during reentry February 1, 2003
OV-103	Discovery	First launched on August 30, 1984
OV-104	Atlantis	First launched on October 3, 1985
OV-105	Endeavour	First launched on May 7, 1992

In addition to the test articles and Orbiters produced for use in the Shuttle program, there are also various mockups on display throughout the world:

Space Shuttle Explorer, a full scale replica of an Orbiter at the Kennedy Space Center visitor's complex
Space Shuttle Adventure, a full scale mockup of an Orbiter mid-deck and flight deck at Space Center Houston

[edit] Shuttle applications

Current and past Space Shuttle's applications include:

Crew rotation and servicing of Mir and the ISS
Manned servicing missions, such as to the Hubble Space Telescope (HST)
Manned experiments in LEO
Carry to LEO:
- Large satellites — these have included the HST
- Components for the construction of the ISS
- Supplies
Carry satellites with a booster, the Payload Assist Module (PAM-D) or the Inertial Upper Stage (IUS), to the point where the booster sends the satellite to:
- A higher Earth orbit; these have included:
  - Chandra X-ray Observatory
  - Many TDRS satellites
  - Two DSCS-III (Defense Satellite Communications System) communications satellites in one mission
  - A Defense Support Program satellite
- An interplanetary orbit; these have included:

[edit] Flight statistics

Shuttle	Flight days	Orbits	Distance		Flights	Longest flight (in days)	Crews	EVAs	Mir/ISS docking	Satellites deployed
Shuttle	Flight days	Orbits	mi	km	Flights	Longest flight (in days)	Crews	EVAs	Mir/ISS docking	Satellites deployed
Columbia †	300.74	4,808	125,204,911	201,497,772	28	17.66*	160	7	0 / 0	8
Challenger †	62.41	995	25,803,940	41,527,416	10	8.23	60	6	0 / 0	10
Discovery	281.45	4,433	115,140,673	185,235,454	33	13.89	206	35	1 / 7	31
Atlantis	243.99	3,654	94,808,732	152,534,078	27	12.89	167	21	7 / 7	14
Endeavour	206.60	3,259	85,072,077	136,910,237	19	16.63	130	29	1 / 6	3
Total	1,095.19	17,149	446,030,333	717,704,957	117	—	813	101	9 / 20	66

(as of 22 December 2006)

* STS-80, a flight during November 1996.

† No longer in service (Destroyed)

[edit] Accidents

The Challenger exploded 73 seconds after liftoff.

As of 2006, two Shuttles have been destroyed in 115 missions, both with the loss of the entire crew (14 astronauts total):

Challenger — lost 73 seconds after liftoff, January 28, 1986

Further information: Space Shuttle Challenger disaster

Columbia — lost approximately 16 minutes before landing, February 1, 2003

Further information: Space Shuttle Columbia disaster

This gives a 2% death rate per astronaut per flight, and a failure rate of almost 1 every 60 missions.

[edit] Current status

Since the Space Shuttle Columbia disaster in 2003, the ISS had been operating on a skeleton crew of two and is currently being serviced primarily by Russian space vehicles. While the "return to flight" mission STS-114 in 2005 was successful, a similar piece of foam from a different portion of the tank was shed. Although the debris did not strike the Orbiter, the program was grounded once again.

The second "Return to Flight" mission, STS-121, launched on July 4, 2006, at 2:37:55 PM (EDT), after two previous launches were scrubbed because of lingering thunderstorms and high winds around the launch pad and the launch took place despite objections from its chief engineer and safety head. This mission increased the ISS crew to three. A five-inch crack in the foam insulation of the external tank gave cause for concern; however, the Mission Management Team gave the go for launch. ^[3] Space Shuttle Discovery touched down successfully on July 17, 2006 at 9:14:43 AM (EDT) on Runway 15 at the Kennedy Space Center.

Following the success of STS-121, the next mission, STS-115, is scheduled for launch on August 28, 2006, following a 24-hour delay due to severe weather in the vicinity of Kennedy, including a lightning strike at the launch pad where the shuttle was undergoing launch preparations.

The Shuttle program is scheduled for mandatory retirement in 2010. The Shuttle's planned succesor is Project Constellation with its Ares I and Ares V launch vehicles and Crew Exploration Vehicle. NASA hopes to launch 16 more shuttle flights before then. ^[4]

[edit] Costs

The total cost of the Shuttle program has been $145 billion as of early 2005 , and is estimated to be $174 billion when the Shuttle retires in 2010. NASA's budget for 2005 allocated 30%, or $5 billion, to Space Shuttle operations; ^[5] this was decreased in 2006 to a request of $4.3 billion. ^[6]

Per-launch costs can be measured by dividing the total cost over the life of the program (including buildings, facilities, training, salaries, etc) by the number of launches. With 115 missions (as of 6 August 2006), and a total cost of $150 billion ($145 billion as of early 2005 + $5 billion for 2005 ^[5], this gives approximately $1.3 billion per launch. Another method is to calculate the incremental (or marginal) cost differential to add or subtract one flight — just the immediate resources expended/saved/involved in that one flight. This is about $60 million [3][4].

Early cost estimates of $118 per pound ($260/kg) of payload were based on marginal or incremental launch costs, and based on 1972 dollars and assuming a 65,000 pound (30,000 kg) payload capacity.[5] [6] Correcting for inflation, this equates to roughly $36 million incremental per launch costs. Compared to this, today's actual incremental per launch costs are about 50% more, or $60 million per launch.

[edit] Criticism

Main article: Criticism of the Space Shuttle program

The Space Shuttle program has been criticized for failing to achieve its promised cost and utility goals, as well as design, cost, management, and safety issues.

After both the Challenger disaster and the Columbia disaster, high profile boards convened to investigate the accidents with both committees returning praise and serious critiques to the program and NASA management. One of the most famous of these criticisms came from Nobel Prize winner Richard Feynman.

[edit] Terrestrial transportation vehicles

The Crawler-Transporter carries the Mobile Launcher Platform and the Space Shuttle from the Vehicle Assembly Building to Launch Complex 39.
The Shuttle Carrier Aircraft are two modified Boeing 747s. Either can fly an Orbiter from alternative landing sites back to Cape Canaveral.
A 36-wheeled transport trailer, originally built for the U.S. Air Force's launch facility at Vandenberg Air Force Base in California (since then converted for Delta IV rockets) that would transport the Orbiter from the landing facility to the launch pad, which allowed both "stacking" and launch without utilizing a separate VAB-style building and crawler-transporter roadway. Prior to the closing of the Vandenberg facility, Orbiters were transported from the OPF to the VAB on its undercarriage, only to be raised when the Orbiter was being lifted for attachment to the SRB/ET stack. The trailer allows the transportation of the Orbiter from the OPF to either the SCA-747 "Mate-Demate" stand or the VAB without placing any additional stress on the undercarriage.

[edit] See also

GRiD Compass the early laptop carried aboard the shuttle.
Human spaceflight
List of human spaceflights
List of human spaceflights chronologically
List of space shuttle missions
NASA Space Shuttle decision
Shuttle Derived Launch Vehicle
Shuttle SERV
Space disaster
Space exploration
Space Shuttle abort modes
Space Shuttle crews

[edit] Fiction

Space shuttles in fiction
'Shuttle' Game DOS-based shuttle simulator from the 1990s.
Orbiter a freeware simulator that allows users to fly various spacecraft including the Shuttle.

[edit] Physics

[edit] Similar spacecraft

v • d • e United States government human spaceflight programs
Active: Space Shuttle \| ISS (joint) \| Project Constellation (future)
Past: X-15 (suborbital) \| Mercury \| Gemini \| Apollo \| Skylab \| Apollo-Soyuz Test Project (joint, USSR) \| Shuttle-Mir (joint, Russia)
Cancelled: MISS \| Orion \| Dyna-Soar \| Manned Orbiting Laboratory \| Space Station Freedom (now ISS) \| Orbital Space Plane

v • d • e Space Shuttles
	US Space Shuttle program Enterprise (atmospheric tests) Pathfinder (ground tests) Columbia (destroyed 2003) Challenger (destroyed 1986) Discovery (active) Atlantis (active) Endeavour (active)	Soviet Buran program OK-GLI (BST-02) (aerotester) Buran (retired, destroyed 2002) Ptichka (95–97% completed, unused) 2.01 (incomplete) 2.02 (partially dismantled) 2.03 (dismantled)