Alan Shepard explosion caused the moon landing to be aborted and nearly resulted in the loss of the crew. It became a joke between Shepard and Lovell, who would offer to give Shepard back the mission each time they bumped into each other. The failure of Apollo 13 delayed Apollo 14 until 1971 so that modifications could be made to the spacecraft. The target of the Apollo 14 mission was switched to the Fra Mauro formation, the intended destination of Apollo 13. Shepard made his second space flight as Commander of Apollo 14 from January 31 to February 9, 1971. It was
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