A re-usable crewed launch vehicle; officially referred to as a space transportation system (STS). The first-generation US shuttle launched in April 1981, managed by NASA's Johnson and Marshall Space Centers. The first Soviet shuttle, Buran, was launched in November 1988 for a single test flight without crew, using the Energiya booster. The European Space Agency shuttle Hermes programme was cancelled after several years' development. The US shuttle carries up to seven crew, and is capable of launching a 24 400-kg/53 700-lb payload into low Earth orbit; missions are up to 14 days' duration. It comprises a delta-winged lifting body orbiter with main engines, a jettisonable external fuel tank, and two auxiliary solid rocket boosters. The fleet comprised four vehicles: Columbia (first launched 1981), Challenger (1983), Discovery (1984), and Atlantis (1985). It has been successfully used to launch numerous science and applications satellites and on-board experiments, to carry the Spacelab module, and to retrieve spacecraft from orbit. The Challenger explosion on the 25th flight (28 Jan 1986) 73 sec after launch caused the loss of the crew. The first reflight took place in September 1988, and a replacement orbiter, Endeavour, became operational in May 1992. A disaster on re-entry in February 2003 destroyed Columbia with the loss of all crew. The launch in 2005 of Discovery, the sister ship to Columbia, was the first since NASA grounded all shuttle flights following the disaster. Once docked with the International Space Station (ISS), an astronaut carried out a pioneering six-hour spacewalk to the orbiter's underside to effect repairs to the heatshield. Loss of foam insulation from the tanks during launch led to further shuttle launches being placed on hold until the problems were resolved. The shuttle was re-launched in July 2006 on a successful 13-day mission to the ISS, and in September that year Atlantis completed a 12-day mission to re-start ISS construction.
In early 2006 NASA announced that Atlantis will be the first of the three remaining shuttles to be retired, and will probably make four or five more flights before being grounded. The shuttle programme ends in 2010 and the next-generation vehicles are expected to be ready before 2014.
Space Shuttle|
Space Shuttle Atlantis launches on mission STS-71 |
||
| Fact sheet | ||
|---|---|---|
| Function | Manned Re-usable Spaceplane | |
| Manufacturer |
United Space Alliance: Thiokol/Boeing (SRBs) Lockheed Martin (Martin Marietta) - (ET) Rockwell (orbiter) |
|
| Country of origin | USA | |
| Size | ||
| Height | 56.14 m (149.6 ft) | |
| Diameter | 8.7 m (28.5 ft) | |
| Mass | 2,029,203 kg (4,474,574 lb) | |
| Stages | 2 | |
| Capacity | ||
| Payload to LEO | 24,400 kg (53,700 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 | 116 | |
| Successes | 112 | |
| Failures | 2 | |
| Partial Failures | 2 | |
| Maiden flight | 04/12/81 | |
| Notable payloads |
Galileo Magellan probe Hubble |
|
| Boosters (Stage 0) - Solid Rocket Boosters | ||
| No boosters | 2 | |
| Engines | 1 solid | |
| Thrust | 11,520 kN (2,589,800 lbf) | |
| Specific Impulse | 269 sec | |
| Burn time | 124 seconds | |
| Fuel | solid | |
| First Stage - External Tank | ||
| Engines |
(none) (3 SSMEs located on Orbiter) |
|
| Thrust | 6,834.3 kN (1,536,312 lbf) | |
| Specific Impulse | 455 sec | |
| Burn time | 480 seconds | |
| Fuel | LOX/LH2 | |
| Second Stage - Orbiter | ||
| Engines | 2 OME | |
| Thrust | 53.367 kN (11,997 lbf) | |
| Specific Impulse | 316 sec | |
| Burn time | 1250 seconds | |
| Fuel | N2O4/MMH | |
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 eleven could be accommodated in emergency) and up to 50,000 lb (22,700 kg) of payload into low earth orbit. 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.
Four space shuttles were initially constructed: Columbia, Challenger, Discovery and Atlantis.
NASA announced in 2004 that the Space Shuttle will be retired in 2010 and replaced by the Orion, a new vehicle that is designed to take humans to the Moon and beyond.
Description
Shuttles are each a partially reusable launch system composed of three main assemblies: the reusable Orbiter Vehicle (OV), the expendable External Tank (ET), and the two reusable Solid Rocket Boosters (SRBs).
Orbiter Vehicle
The Orbiter resembles an aircraft with double-delta wings, swept 81° at the inner leading edge and 45° at the outer leading edge. Three Space Shuttle Main Engines (SSMEs) are mounted on the Orbiter's aft fuselage in a triangular pattern. The three engines can swivel 10.5 degrees up and down and 8.5 degrees from side to side during ascent to change the direction of their thrust and steer the Shuttle as well as push.
External Tank
The External Tank (ET) provides approximately 535,000 gallons (2.025 million liters) of liquid hydrogen and liquid oxygen propellant to the SSMEs.
Solid Rocket Boosters
Two Solid Rocket Boosters (SRBs) provide about 83% of the vehicle's thrust at liftoff and during the first stage ascent.
Flight systems
Early Shuttle missions took along the GRiD Compass, arguably one of the first laptop computers.
The shuttle was one of the earliest craft to use a computerized fly-by-wire digital flight control system.
The design goal of the shuttle DPS is fail operational/fail safe reliability.
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 software for the shuttle computers is written in a high-level language called HAL/S, somewhat similar to PL/I.
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).
Upgrades
Internally the Shuttle remains largely similar to the original design, with the exception of the improved avionics computers. With the coming of the ISS, the Orbiter's internal airlocks have been replaced with external docking systems to allow for a greater amount of cargo to be stored on the Shuttle's mid-deck during Station resupply missions.
The Space Shuttle Main Engines have had several improvements to enhance reliability and power.
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 resulting "light-weight external tank" has been used on the vast majority of Shuttle missions.
A cargo-only, unmanned variant of the Shuttle has been variously proposed and rejected since the 1980s. It is called the Shuttle-C and would trade re-usability for cargo capability with large potential savings from reusing technology developed for the Space Shuttle.
On the first four Shuttle missions, astronauts wore full-pressure Launch Entry Suit (LES) including a helmet during ascent and descent.
Technical data
Orbiter Specifications (for Endeavour, OV-105)
Length: 122.17 ft (37.24 m) Wingspan: 78.06 ft (23.79 m) Height: 58.58 ft (17.25 m) Empty Weight: 151,205 lb (68,586.6 kg) Gross Liftoff Weight: 240,000 lb (109,000 kg) Maximum Landing Weight: 230,000 lb (104,000 kg) Main Engines: Three Rocketdyne Block 2 A SSMEs, each with a sea level thrust of 393,800 lbf (178,624 kgf / 1.75 MN) Maximum Payload: 55,250 lb (25,061.4 kg) Payload Bay dimensions: 15 ft by 60 ft (4.6 m by 18.3 m) Operational Altitude: 100 to 520 nmi (185 to 1,000 km) Speed: 25,404 ft/s (7,743 m/s, 27,875 km/h, 17,321 mi/h) Crossrange: 1,085 nautical miles (2,009.4 km) Crew: Seven (Commander, Pilot, two Mission Specialists, and three Payload Specialists), two for minimum.External Tank Specifications (for SLWT)
Length: 153.8 ft (46.9 m) Diameter: 27.6 ft (8.4 m) Propellant Volume: 535,000 gallon (2,030,000 L) Empty Weight: 58,500 lb (26,559 kg) Gross Liftoff Weight: 1.667 million lb (757,000 kg)Solid Rocket Booster Specifications
Length: 149.6 ft (45.6 m) Diameter: 12.17 ft (3.71 m) Empty Weight: 139,490 lb (63,272.7 kg) Gross Liftoff Weight: 1.3 million lb (590,000 kg) Thrust (sea level, liftoff): 2.8 million lbf (1,270,058 kgf / 12.46MN)System Stack Specifications
Height: 184.2 ft (56.14 m) Gross Liftoff Weight: 4.5 million lb (2.04 million kg) Total Liftoff Thrust: 6.781 million lbf (3.076 million kgf / 30.18MN)Launch
The shuttle will not be launched under conditions where it could be struck by lightning. 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.
At T minus 16 seconds, the massive sound suppression system (SPS) begins to drench the Mobile Launcher Platform (MLP) and SRB trenches with 300,000 U.S. gallons (1,135,623 L) of water to protect the Orbiter from damage by acoustical energy and rocket exhaust reflected from the flame trench and MLP during liftoff.
The three Space Shuttle Main Engines (SSMEs) start at T minus 6.6 seconds. The main engines ignite sequentially via the shuttle's general purpose computers (GPC's) at 0.25 second intervals. After the SRBs reach a stable thrust ratio, pyrotechnic bolts are detonated by radio controlled signals from the shuttle's GPC's to release the vehicle. The GPC's mandate ignition sequences via the "Master Events Controller," a computer program integrated with the shuttle's four redundant computer systems. After the main engines start, but while the solid rocket boosters are still clamped to the pad, the offset thrust from the Shuttle's three main engines causes the entire launch stack (boosters, tank and shuttle) to flex forwards about 2m at cockpit level.
Shortly after clearing the tower the Shuttle begins a roll and pitch program so that the vehicle is below the external tank and SRBs. For missions towards the International Space Station, the shuttle must reach an azimuth of 51.6 degrees inclination 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 avoid overspeeding and hence overstressing the Shuttle, particularly in vulnerable areas such as the wings.
126 seconds after launch, explosive bolts release the SRBs and small separation rockets push them laterally away from the vehicle. The Shuttle then begins accelerating to orbit on the Space Shuttle main engines.
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 maintains altitude whilst it accelerates horizontally towards orbit.
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, largely for astronaut comfort.
Before complete depletion of propellant, as running dry would destroy the engines, the main engines are shut down.
To prevent the shuttle from following the external tank back into the atmosphere, the OMS engines are fired to raise the perigee out of the atmosphere.
Landing
The vehicle begins reentry by firing the OMS engines in the opposite direction to orbital motion for about three minutes.
When the approach and landing phase begins, the Orbiter is at 10,000 ft (3048 m) altitude, 7.5 miles (12.1 km) to the runway.
After landing, the vehicle stands on the runway for several minutes to permit the fumes from poisonous hydrazine, used as propellant for attitude control, to dissipate, and for the shuttle fuselage to cool before the astronauts disembark.
Conditions permitting, the Space Shuttle will always land at Kennedy Space Center. A landing at Edwards means that the shuttle must be mated to the Shuttle Carrier Aircraft and returned to Cape Canaveral, costing NASA roughly an additional million dollars.
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