NASA's Space Shuttle, officially called the Space Transportation System (STS), is the spacecraft currently used by the United States government for its human spaceflight missions and is scheduled to be retired from service in 2010. At launch, it consists of a rust-colored external tank (ET), two white, slender Solid Rocket Boosters (SRBs), and the orbiter, a winged spaceplane which is the space shuttle in the narrowest sense.

The orbiter carries astronauts and payload such as satellites or space station parts into low earth orbit, into the Earth's upper atmosphere or thermosphere. Usually, five to seven crew members ride in the orbiter. The payload capacity is 22,700 kilograms (50,000 lb). When the orbiter's mission is complete it fires its Orbital Maneuvering System (OMS) thrusters to drop out of orbit and re-enters the lower atmosphere. During the descent, the shuttle orbiter decelerates from hypersonic speed primarily by aerobraking and then for the landing phase it acts as a glider, making a completely unpowered ("deadstick") landing.

The Shuttle is the first orbital spacecraft designed for partial reusability. It carries payloads to low Earth orbit, 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. 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 commercial and classified satellites, and have the cross-range recovery range to meet classified USAF missions requirement for a one-around abort for a launch to a polar orbit. 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.