Saturn, in space exploration, any of a series of large two- and three-stage vehicles for launching spacecraft, developed by the United States beginning in 1958 in connection with the crewed Apollo Moon-landing program. Saturn I, the first U.S. rocket specifically developed for spaceflight, was a two-stage liquid-fuel vehicle that placed uncrewed test versions of Apollo spacecraft and other satellites into Earth orbit in the early 1960s. The first firing, on October 27, 1961, was followed by nine more successful launches. An upgraded version, the Saturn IB, was used for uncrewed and crewed Apo...