Space Shuttle

NASA's Space Shuttle, officially called Space Transportation System (STS), is the United States government's current manned launch vehicle. At launch, it consists of a rust-colored external tank (ET), two white, slender solid rocket boosters (SRBs), and a winged orbiter (the space shuttle in the narrow sense). The orbiter carries astronauts and payload such as satellites or space station parts into low earth orbit. Normally, five to seven astronauts ride in the orbiter, with two pilots, eight have been carried, and eleven could be accommodated in an emergency landing. The payload capacity is 50,000 lb (22,700 kg). When the orbiter's mission is complete, it fires its orbital maneuvering thrusters to drop out of orbit and re-enters the Earth's atmosphere. During the descent and landing, the shuttle orbiter acts as a glider and makes a completely unpowered ("dead stick") landing. Five spaceworthy orbiters were built, of which three remain.
The Shuttle is the first orbital spacecraft designed for partial reusability. It carries large payloads to various orbits, 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, but this capacity has not been used often. However, it has been used to return large payloads from the ISS to Earth, as the Russian Soyuz spacecraft has limited capacity for return payloads. Each Shuttle was designed for a projected lifespan of 100 launches or 10 years' operational life. The man responsible for the design of 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 spy satellites, and have the cross-range recovery range to meet classified USAF missions. Factors involved in opting for 'reusable' 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.
The first orbiter, Enterprise, was not built for actual space flight, and was used only for testing purposes. Enterprise was followed by four operational space shuttles: Columbia, Challenger, Discovery and Atlantis. Challenger was destroyed on launch in 1986, and Endeavour was built as a replacement. Columbia was destroyed on re-entry in 2003. One could say all up 6 shuttles have been built including Enterprise, 5 of them being space worthy.
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.