Moon by the Soviet Union's Luna 2, an unmanned spacecraft. The United States' NASA Apollo program achieved the only manned lunar missions to date, beginning with the first manned orbital mission by Apollo 8 in 1968, and six manned landings between 1969 and 1972, with the first being Apollo 11. These missions returned lunar rocks which have been used to develop a geological understanding of the Moon's origin, internal structure, and the Moon's later history. Since the Apollo 17 mission in 1972, the Moon has been visited only by unmanned spacecraft. Both the Moon's natural prominence in the earthly sky and
Exploration of the Moon there were 65 Moon landings (with 10 in 1971 alone), but after Luna 24 in 1976 they suddenly stopped. The Soviet Union started focusing on Venus and space stations and the U.S. on Mars and beyond, and on the Skylab and Space Shuttle programs. Before the Moon race the US had pre-projects for scientific and military moonbases: the Lunex Project and Project Horizon. Besides manned landings, the abandoned Soviet manned lunar programs included the building of a multipurpose moonbase "Zvezda", the first detailed project, complete with developed mockups of expedition vehicles and surface modules. In 1990 Japan visited the Moon