Discovery lifts off at the start of STS-120.

Space Shuttle

The Space Shuttle was a partially reusable low Earth orbital spacecraft system operated by the U.S. National Aeronautics and Space Administration (NASA), as part of the Space Shuttle program. Its official program name was Space Transportation System (STS), taken from a 1969 plan for a system of reusable spacecraft of which it was the only item funded for development.The first of four orbital test flights occurred in 1981, leading to operational flights beginning in 1982. Five complete Shuttle systems were built and used on a total of 135 missions from 1981 to 2011, launched from the Kennedy Space Center (KSC) in Florida. Operational missions launched numerous satellites, interplanetary probes, and the Hubble Space Telescope (HST); conducted science experiments in orbit; and participated in construction and servicing of the International Space Station. The Shuttle fleet's total mission time was 1322 days, 19 hours, 21 minutes and 23 seconds.

Shuttle components included the Orbiter Vehicle (OV), a pair of recoverable solid rocket boosters (SRBs), and the expendable external tank (ET) containing liquid hydrogen and liquid oxygen. The Shuttle was launched vertically, like a conventional rocket, with the two SRBs operating in parallel with the OV's three main engines, which were fueled from the ET. The SRBs were jettisoned before the vehicle reached orbit, and the ET was jettisoned just before orbit insertion, which used the orbiter's two Orbital Maneuvering System (OMS) engines. At the conclusion of the mission, the orbiter fired its OMS to de-orbit and re-enter the atmosphere. The orbiter then glided as a spaceplane to a runway landing, usually at the Shuttle Landing Facility of KSC or Rogers Dry Lake in Edwards Air Force Base, California. After landing at Edwards, the orbiter was flown back to the KSC on the Shuttle Carrier Aircraft, a specially modified Boeing 747.

The first orbiter, Enterprise, was built in 1976 for use in Approach and Landing Tests and had no orbital capability. Four fully operational orbiters were initially built: Columbia, Challenger, Discovery, and Atlantis. Of these, two were lost in mission accidents: Challenger in 1986 and Columbia in 2003, with a total of fourteen astronauts killed. A fifth operational (and sixth in total) orbiter, Endeavour, was built in 1991 to replace Challenger. The Space Shuttle was retired from service upon the conclusion of Atlantis's final flight on July 21, 2011.

Important specification.

Function	Crewed orbital launch and reentry
Manufacturer	United Space AllianceThiokol/Alliant Techsystems (SRBs)Lockheed Martin/Martin Marietta (ET)Boeing/Rockwell (orbiter)
Country of origin	United States of America
Project cost	US$ 209 billion (2010)
Cost per launch	US$ 450 million (2011)to 1.5 billion (2011)
Size
Height	56.1 m (184.2 ft)
Diameter	8.7 m (28.5 ft)
Mass	2,030 t (4,470,000 lbm)
Stages	2
Capacity
Payload to LEO	27,500 kg (60,600 lb)
Payload to ISS	16,050 kg (35,380 lb)
Payload to GTO	3,810 kg (8,400 lb)
Payload to Polar orbit	12,700 kg (28,000 lb)
Payload to Earth return	14,400 kg (31,700 lb)
Launch history
Status	Retired
Launch sites	LC-39, Kennedy Space CenterSLC-6, Vandenberg AFB (unused)
Total launches	135
Successes	133 launches and landings
Failures	2Challenger (launch failure, 7 fatalities),Columbia (re-entry failure, 7 fatalities)
First flight	April 12, 1981
Last flight	July 21, 2011
Notable payloads	Tracking and Data Relay SatellitesSpacelabHubble Space TelescopeGalileo, Magellan, UlyssesMir Docking ModuleISS components
No. boosters	2
Engines	2 solid
Thrust	12,500 kN (2,800,000 lbf) each, sea level liftoff
Specific impulse	269 seconds (2.64 km/s)
Burn time	124 s
Fuel	Solid (Ammonium perchlorate composite propellant)
First stage                 Orbiter plus External Tank
Engines	3 SSMEs located on Orbiter
Thrust	5,250 kN (1,180,000 lbf) total, sea level liftoff
Specific impulse	455 seconds (4.46 km/s)
Burn time	480 s
Fuel	LOX/LH2