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 up to 50,000 lb (22 700 kg) of payload into low earth orbit. When its mission is complete, the Shuttle can independently move itself out of orbit (by means of its maneuvering thrusters) and re-enter the Earth's atmosphere. During descent and landing, the Shuttle Orbiter acts as a glider and makes a completely unpowered landing.

The Shuttle is the only winged manned spacecraft to achieve orbit and land. Its missions involve carrying large payloads to various orbits (including segments to be added to the International Space Station (ISS)), providing crew rotation for the International Space Station, and performing service missions. The orbiter can also recover satellites and other payloads from orbit and return them to Earth, but its use in this capacity is rare. However, the Shuttle has previously been used to return large payloads from the ISS to Earth, as the Russian Soyuz spacecraft has limited capacity for return payloads. Each vehicle was designed with a projected lifespan of 100 launches, or 10 years' operational life.

The program started in the late 1960s and has dominated NASA's manned operations since the mid-1970s. According to the Vision for Space Exploration, use of the Space Shuttle will be focused on completing assembly of the ISS by 2010, after which it will be replaced by the new Orion spacecraft.

Even before the Apollo moon landing in 1969, in October 1968 NASA began early studies of space shuttle designs. The early studies were denoted "Phase A", and in June 1970, "Phase B", which were more detailed and specific.

In 1969 President Richard Nixon formed the Space Task Group, chaired by vice president Spiro T. Agnew. They evaluated the shuttle studies to date, and recommended a national space strategy including building a space shuttle.

In October 1969, at a Space Shuttle symposium held in Washington, George Mueller (NASA deputy administrator) presented opening remarks: *
"The goal we have set for ourselves is the reduction of the present costs of operating in space from the current figure of $1,000 a pound for a payload delivered in orbit by the Saturn V, down to a level of somewhere between $20 and $50 a pound. By so doing we can open up a whole new era of space exploration. Therefore, the challenge before this symposium and before all of us in the Air Force and NASA in the weeks and months ahead is to be sure that we can implement a system that is capable of doing just that.
Let me outline three areas which, in my view, are critical to the achievement of these objectives.

One is the development of an engine that will provide sufficient specific impulse, with adequate margin to propel its own weight and the desired payload.

A second technical problem is the development of the reentry heat shield, so that we can reuse that heat shield time after time with minimal refurbishment and testing.

The third general critical development area is a checkout and control system which provides autonomous operation by the crew without major support from the ground and which will allow low cost of maintenance and repair.

reduce substantially the cost of space operations and

provide a future capability designed to support a wide range of scientific, defense, and commercial uses.