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Space Shuttle orbiter

Space Shuttle orbiter

The Space Shuttle orbiters are the orbital spacecraft of the Space Shuttle program operated by NASA, the space agency of the United States. Each orbiter is a reusable winged "spaceplane", a mixture of rocket, spacecraft, and aircraft. The orbiters carry crews and payloads into Earth orbit, perform on-orbit operations, then re-enter the atmosphere and land like gliders to return their crews and any on board payloads to Earth.

In addition to the crew and payload the reusable orbiter carries most of the main propulsion system, but the propellant for its three main engines is fed from a non-reusable external tank, and two reusable solid rocket boosters help propel both the orbiter and the external tank during the first two minutes of ascent.

Description

The Orbiter resembles an 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 45° 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. It is roughly the size of a McDonnell Douglas DC-9.

The Orbiter's crew cabin consists of three levels: the flight deck, the mid-deck, and the utility area. The upper-most is the flight deck which seats the commander and pilot, with two mission specialists behind them. The mid-deck, which is below the flight deck, has three more seats for the rest of the crew members. The galley, toilet, sleep locations, storage lockers, and the side hatch for entering/exiting the vehicle are also located on the mid-deck, as is the airlock hatch. The airlock has another hatch into the payload bay. It allows two astronauts, wearing their Extravehicular Mobility Unit (EMU) space suits, to depressurize before a space walk.

The Orbiter has a large 60 by 15 ft (18 m by 4.6 m) payload bay, filling most of the midfuselage. The payload bay doors have heat radiators mounted on their inner surfaces, and so are kept open for thermal control while the Shuttle is in orbit. Thermal control is also maintained by adjusting the orientation of the Shuttle relative to Earth and Sun. Inside the payload bay is the Remote Manipulator System, also known as the Canadarm, a robot arm used to retrieve and deploy payloads. Until the loss of Columbia, the Canadarm had been used only on those missions where it was needed. Since the arm is a crucial part of the Thermal Protection Inspection procedures now required for Shuttle flights, it will probably be included on all future flights. Three fuel cells are located under the payload bay area. They consume onboard liquid oxygen and liquid hydrogen storages to generate all the electrical power for the vehicle from launch to landing.

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. The aft fuselage also houses three auxiliary power units. The APUs are hydrazine-fueled turbopumps to provide hydraulic pressure for the hydraulic system, which gimbals the three main engines, controls aerosurfaces, and deploys the landing gears.

Two Orbital Maneuvering System (OMS) thusters are mounted in two separate pods in the Orbiter's aft fuselage located between the SSMEs and the vertical stabilizer of the Orbiter. The OMS engines provide significant thrust for coarse orbital maneuvers, including insertion, circularization, transfer, rendezvous, deorbit, abort to orbit, and abort once around.

The Reaction Control System (RCS) is comprised of 44 smaller thrusters and provides attitude control and translation along the pitch, roll, and yaw axes during the flight phases of orbit insertion, orbit, and re-entry. The forward RCS jets near the nose of the Orbiter include 12 primary and 2 vernier RCS engines. The aft RCS engines are located in the OMS pods of the vehicle and include 12 primary and 2 vernier RCS engines in each pod. The RCS system provides the finest control of the Orbiter and is used for the maneuvering during the rendezvous pitch maneuver, docking and undocking with the International Space Station.

The Thermal Protection System (TPS) covers the outside of the Orbiter, protecting it from the cold soak of -121 °C (-250 °F) in space to the 1649 °C (3000 °F) heat of re-entry.

The orbiter structure is made primarily from aluminum alloy, although the engine thrust structure is made from titanium alloy. The windows, which are made out of a polycarbonate, are tinted with the same ink used to make American Banknotes.

The shuttle has neither anti collision, navigation nor landing lights. When landing at night the runway is flooded with light from ground spotlights.

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 lbs (68,586.6 kg)
  • Gross Liftoff Weight: 240,000 lbs (109,000 kg)
  • Maximum Landing Weight: 230,000 lbs (104,000 kg)
  • Main Engines: Three Rocketdyne Block 2 A SSMEs, each with a sea level thrust of 393,800 lbf (178,624 kgf / 1.75MN)
  • 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 nm (185 to 1,000 km)
  • Speed: 25,404 ft/s (7,743 m/s, 27,875 km/h, 17,321 mph)
  • Crossrange: 1,085 nautical miles (2,009.4 km)
  • Crew: 6-7 (Commander, Pilot, 4-5 Mission Specialists and/or Payload Specialists), 2 (Commander and Pilot) for minimum.

Fleet

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. The only shuttle to have the distinct characteristic as NASA's Return to Flight vehicle, following the Challenger and Columbia disasters.
OV-104
Atlantis First launched on October 3, 1985
OV-105
Endeavour First launched on May 7, 1992

  • Enterprise was a prototype designed to test Space Shuttle behavior in atmospheric flight. It performed various performance tests from February 12, 1977 to October 26, 1977. Several times from the late 1970s to the mid-1980s NASA considered retrofitting it for space flight but because of a redesign during the Columbia's construction it was deemed too costly. As a prototype Space Shuttle, rocket engines or a proper heat shield were never installed. It is currently on display at the Smithsonian's National Air and Space Museum Steven F. Udvar-Hazy Center at Dulles International Airport, where it is the centerpiece of the space flight collection.
  • Columbia first launched on April 12, 1981. On February 1, 2003, Columbia disintegrated during re-entry on its 28th mission.
  • Challenger first launched on April 4, 1983. On January 28, 1986 it broke up 73 seconds after the launch of its 10th mission.
  • Discovery first launched on August 30, 1984. It has flown 33 missions and is still operational today. It is due to be retired in 2010.
  • Atlantis first launched on October 3, 1985. It has flown 26 missions and is still operational today. It is scheduled to be retired in 2010.
  • Endeavour first launched on May 7, 1992. It has flown 19 missions and is still operational today. It is due to be retired in 2010.

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:

Flight statistics

See also

References

External links

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