Apollo 17 became the last mission to launch humans on the moon. With two astronauts on board, the lunar module Challenger ...

The answer depends on many factors, including the amount of fuel needed, the moon's orbit and the mission's objectives.

After the failure of Apollo 13 to land on the moon, NASA organized and completed four more Apollo missions, with eight men walking on the moon to bring the total to 12, all American astronauts.