Space Shuttle

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NASA's Space Shuttle is the world's first reusable spacecraft, and the first spacecraft capable of carrying large satellites both to and from Earth orbit. Each shuttle is designed for a projected lifespan of 100 launches. One of the main purposes of the program was to construct and service a space station. With the International Space Station this purpose is now a reality.

The shuttle program was launched on January 5 1972, when President Richard M. Nixon announced that NASA would proceed with the development of a reusable low cost space shuttle system.

The first shuttle orbiter, the Enterprise, was rolled out on September 17, 1976. It was a test platform that never flew in space but was used for approach and landing tests and launch pad studies. It was turned over to the Smithsonian Institute on November 18, 1985. The first fully functional shuttle orbiter was the Columbia, delivered to Kennedy Space Center on March 25 1979 and had its first launch on April 12, 1981 with a crew of two. Challenger was delivered to KSC in July 1982, Discovery was delivered in November 1983, and Atlantis was delivered in April 1985. Challenger was destroyed in an explosion during launch in January 1986 with the loss of all seven astronauts on board, and the orbiter Endeavour was built as a replacement and delivered in May 1991.

The Space Shuttle consists of three main components; the reuseable orbiter itself, a large expendable external fuel tank, and a pair of reusable solid-fuel booster rockets. The fuel tank and booster rockets are jettisoned during ascent. The longest the shuttle has stayed in orbit in a single mission is 17.5 days, on mission STS-80 in November 1996.

The Space Shuttle system has had numerous improvements over the years. The Space Shuttle Main Engines have had several improvements to enhance reliability and power. This is why during launch you may hear curious phrases such as "Go to throttle-up at 106%". This does not mean the engines are being run over-limit. The 100% figure is the power level for the original main engines.

The external tank was originally painted white to match the color of the orbiter and SRBs. It was found that this was unnecessary, and now the external tanks are the brown color of the insulation that covers them. This saves considerable weight, and thereby increases the payload the orbiter can carry into orbit.

And, of course, the SRBs have undergone improvements as well. Notable is the adding of a third O-ring seal to the joints between the segments, which occured after the Challenger accident.

Whilst the shuttle has been a reasonably successful launch vehicle, it was unable to meet its goals of radically reducing flight launch costs, as each mission costs on the order of 500 million dollars rather than initial hopes of $10 to $20 million. Long-term plans exist for replacement cheaper vehicles, possibly using the SSTO methodology.

Space Shuttle stack height: 56.14 meters (184.2 feet) tall
Orbiter alone: 37.23 meters (122.17 feet) long
Wingspan: 23.79 meters (78.06 feet)
Weight at liftoff: 2,041,166 kilograms (4.5 million pounds)
Weight at end of mission: 104,326 kilograms (230,000 pounds)
Maximum cargo to orbit: 28,803 kilograms (63,500 pounds)
Orbit: 185 to 643 kilometers (115 to 400 statute miles)
Velocity: 27,875 kph (17,321 mph)

Public domain picture from NASA



External Links

Orbiter Vehicles
NASA Human Spaceflight - Shuttle Current status of Shuttle missions