NASA developed the Space
Shuttle program, most often referred to as Space Transportation System
(STS), during the 1970’s. NASA’s STS includes intergovernmental
agency requirements and international and joint projects. The Space
Shuttle system consists of four primary elements: an orbiter spacecraft, two
solid rocket boosters (SRB), an external tank to house fuel and oxidizer and
three main engines.
The major system requirements of the program are that the
orbiter and the two SRB can be reusable. The orbiter has carried up to
eight astronauts but is capable of carrying 10 under emergency conditions.
Usual missions last 7 days in space. During a launch, the three
engines and the two SRB provide the initial thrust. After about 2
minutes, the two boosters are spent and are separated from the external
tank. They fall into the ocean where they are recovered. The
main engines continue firing for about 8 minutes. They shut down just
before the craft is in orbit. The external tank is then separated and
follows a ballistic trajectory into the ocean but is not recovered.When the orbiter is ready to return to Earth, the thermal protection system covering the entire craft provides protection from the extremely high temperatures encountered during reentry. This system is also reusable. The unpowered orbiter glides to Earth and lands on a runway like an airplane.
