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
Moon landing around the Moon before returning safely to Earth. Apollo 10 then performed a full dress rehearsal of a manned Moon landing in May 1969. This mission orbited within altitude above the lunar surface, performing necessary low-altitude mapping of trajectory-altering mascons using a factory prototype lunar module that was too overweight to allow a successful landing. With the failure of the unmanned Soviet sample return Moon landing attempt Luna 15 in July 1969, the stage was set for Apollo 11. Plans for manned Moon exploration originated during the Eisenhower administration. In a series of mid-1950s articles in "Collier's" magazine, Wernher von