Contents
Space Shuttle
From Wikipedia, the free encyclopedia
Space Shuttle Discovery launches at the start of STS-120.
Function Manned partially re-usable launch and reentry system
Manufacturer United Space Alliance:
Thiokol/Alliant Techsystems (SRBs)
Lockheed Martin (Martin Marietta) – (ET)
Rockwell/Boeing (orbiter)
Country of origin
United States
Size
Height 184 ft (56.1 m)
Diameter 28.5 ft (8.69 m)
Mass 4,470,000 lb (2,030 t)
Stages 2
Capacity
Payload to LEO 24,400 kg (53,600 lb)
Payload to
GTO 3,810 kg (8,390 lb)
Launch history
Status Active
Launch sites LC-39, Kennedy Space Center
SLC-6, Vandenberg AFB (unused)
Total launches 130
Successes 129
Failures 1 (launch failure, Challenger)
Other 1 (re-entry failure, Columbia)
Maiden flight April 12, 1981
Notable payloads Tracking and Data Relay Satellites
Spacelab
Great Observatories
Galileo
Magellan
Space Station components
Boosters (Stage 0) - Solid Rocket Boosters
No boosters 2
Engines 1 solid
Thrust 2,800,000 lbf each, sea level liftoff (12.5 MN)
Specific impulse 269 s
Burn time 124 s
Fuel solid
First stage - External Tank
Engines (none)
(3 SSMEs located on Orbiter)
Thrust 1,225,704 lbf total, sea level liftoff (5.45220 MN)
Specific impulse 455 s
Burn time 480 s
Fuel LOX/LH2
Second stage - Orbiter
Engines 2 OME
Thrust 53.4 kN combined total vacuum thrust (12,000 lbf)
Specific impulse 316 s
Burn time 1250 s
Fuel MMH/N2O4
The Space Shuttle, part of the Space Transportation System (STS), is an American spacecraft operated by NASA for orbital human spaceflight missions. The first of four test flights occurred in 1981, which were followed by operational flights beginning in 1982. The system is scheduled to be retired from service in 2010 after 134 launches. Major missions have included launching numerous satellites and interplanetary probes, conducting space science experiments, and servicing and construction of space stations. The Shuttle has been used for orbital space missions by NASA, the U.S. Department of Defense, the European Space Agency, and Germany. The United States funded STS development and shuttle operations.
At launch, the Space Shuttle consists of a dark orange-colored external tank (ET);[1][2] two white, slender Solid Rocket Boosters (SRBs); and the STS Orbiter Vehicle (OV) which contains the crew and payload. Payloads can be launched into higher orbits with either of two different booster stages developed for STS (1 stage PAM or 2 stage IUS).
The shuttle stack launches vertically like a conventional rocket from a mobile launch platform. It lifts off under the power of its two solid rocket boosters (SRBs) and its three main engines (SSMEs), the latter fueled by liquid hydrogen and liquid oxygen from the external tank. The Space Shuttle has a two stage ascent. The boosters are used only for the first stage, while the main engines burn for both stages. About two minutes after liftoff, staging occurs: the SRBs are released, and shortly begin falling into the ocean to be retrieved for reuse. The shuttle orbiter and external tank continue to ascend under power from the three main engines and their inertia. Upon reaching orbit, the main engines are shut down, and the external tank is jettisoned downward and falls to burn up in the atmosphere. However, it is possible for it to be re-used in orbit for various applications.[3] At this point, the orbital maneuvering system (OMS) engines may be used to adjust or circularize the achieved 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.[4] 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 to capture and return large payloads back to Earth.
When the orbiter's space mission is complete it fires its Orbital Maneuvering System (OMS) thrusters to drop out of orbit and re-enter the lower atmosphere.[4] During the descent, the shuttle orbiter passes through different layers of the atmosphere and decelerates from hypersonic speed primarily by aerobraking. In the lower atmosphere and landing phase, it acts as a glider with reaction control system (RCS) thrusters and fly-by wire controlled hydraulically actuated flight surfaces controlling its descent. It then makes a landing on a long runway as a spaceplane. The aerodynamic shape is a compromise between the demands of radically different speeds and air pressures during re-entry, subsonic atmospheric flight, and hypersonic flight. As a result the orbiter has a high sink rate at low altitudes, and transitions from using RCS thrusters in low pressure to flight surfaces at low altitudes.
With more than 2.5 million parts, the Space Shuttle has been called the most complex machine yet created by humanity.[5]
Early history
Though design and construction of the Space Shuttle began in the early 1970s, conceptualization actually began two decades earlier, even before the Apollo program of the 1960s.[6][7] The conceptual idea of a spacecraft returning from space to a horizontal landing begins within NACA, in 1954,[7] in the form of an aeronautics research experiment later to be named the X-15. The NACA proposal was submitted by Walter Dornberger.[7]
In 1957, the X-15 concept further developed into another X-series spaceplane proposal, called the X-20, which was never constructed.[8] Neil Armstrong was selected to pilot both the X-15 and the X-20.[7][8]
Though the X-20 was never built, another spaceplane design similar in function to the X-20 was constructed several years later and was delivered to NASA in January of 1966.[9] It was called the HL-10.[9] "HL" designated its horizontal landing capability after returning from space.[9]
In the mid-1960's the US Air Force conducted a series of classified studies on next-generation space transportation systems and concluded that semi-reusable designs were the best choice from an overall cost basis.[10] They proposed a development program with an immediate start on a "Class I" vehicle based on expendable boosters, followed by a slower development of a "Class II" semi-reusable design, and perhaps a "Class III" fully-reusable design in the further future.[10] In 1967 George Mueller held a one-day symposium at NASA headquarters to study the options.[10] Eighty people attended and presented a wide variety of potential designs, including earlier Air Force designs as the Dyna-Soar (X-20).
In 1968 NASA officially began work on what was then known as the "Integrated Launch and Re-entry Vehicle" (ILRV).[10] At the same time, a separate Space Shuttle Main Engine (SSME) competition was held.[10] NASA offices in Houston and Huntsville jointly issued a Request for Proposal (RFP) for ILRV studies, requesting ideas for a spacecraft that could deliver a payload to orbit but also re-enter the atmosphere and safely fly back to Earth.[10] Included in the proposals was that of a two-stage design, featuring a large booster and a small orbiter, called the DC-3.
In 1969 President Nixon decided to proceed with Space Shuttle development.[11]
In August 1973, the X-24B proved that an unpowered spaceplane could re-enter Earth's atmosphere from space for a safe return to a horizontal landing.
Description
The Space Shuttle is the first orbital spacecraft designed for reusability. It carries different payloads to low Earth orbit, provides crew rotation for the International Space Station (ISS), and performs servicing missions. The orbiter can also recover 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 operational life, although this was later extended. The person in charge of designing the STS was Maxime Faget, who had also overseen the Mercury, Gemini, and Apollo spacecraft designs. The crucial factor in the size and shape of the Shuttle Orbiter was the requirement that it be able to accommodate the largest planned commercial and classified satellites, and have the cross-range recovery range to meet the requirement for classified USAF missions for a once-around abort from a launch to a polar orbit. Factors involved in opting for solid rockets and an expendable fuel tank included the desire of the Pentagon to obtain a high-capacity payload vehicle for satellite deployment, and the desire of the Nixon administration to reduce the costs of space exploration by developing a spacecraft with reusable components.
