Another article in this issue, Space Shuttles and their contribution, provides an overview of the Space Shuttle Program (officially called Space Transportation System – STS), which the U.S. established in the late 1960s. The program commenced on April 12, 1981, with the launching of Columbia STS-1 – the first shuttle orbital flight – and concluded with its last mission, STS-135 flown by Atlantis in July 2011, which retired the final shuttle in the fleet. The Space Shuttle program formally ended on August 31, 2011.