Apollo 12 would have been ready to go in September 1969 if Apollo 11 had failed. Instead, they took a few extra months to give astronauts Pete Conrad, Alan Bean, and Richard Gordon more time to prepare for the second manned lunar landing in the Ocean of Storms.

Apollo 12 was a repeat of the Apollo 11 mission with a few exceptions. First, the two moonwalkers made two walks on the moon, spending nearly four times more time on the lunar surface than Armstrong and Aldrin. Second, because the Apollo 11 Lunar Module landed way off course, the mission planners intended to target the Apollo 12 Lunar Module to a specific target. They would try and land astronauts Conrad and Bean within walking distance of an unmanned spacecraft, Surveyor 3, which landed on the moon in 1967.