 Saturn has been explored only through uncrewed spacecraft launched by NASA, including one mission ("Cassini–Huygens") planned and executed in cooperation with other space agencies.These missions consist of flybys in 1979 by "Pioneer 11", in 1980 by "Voyager 1", in 1982 by "Voyager 2" and an orbital mission by the "Cassini" spacecraft, which lasted from 2004 until 2017.Saturn has at least 62 known moons, although the exact number is debatable since Saturn's rings are made up of vast numbers of independently orbiting objects of varying sizes.