The Space Shuttle program, known as STS (Space Transportation System), was a series of missions conducted by NASA from 1981 to 2011. The primary goal of STS missions was to transport astronauts and cargo to and from low Earth orbit, including the construction and servicing of the International Space Station (ISS). Each mission utilized the reusable Space Shuttle spacecraft, which consisted of an orbiter, solid rocket boosters, and an external fuel tank. During its 135 missions, the STS program enabled significant scientific research and technological advancements. Notable achievements included deploying satellites, conducting experiments in microgravity, and facilitating international cooperation in space exploration. The program concluded with the final flight of STS-135 in July 2011, marking the end of an era in human spaceflight.