Apollo 20: The Secret Mission to the Moon to Salvage an Ancient Alien Spacecraft

The Apollo spaceflight program lasted from 1961 to 1972. Apollo 11 was Neil Armstrong's famous first step. Apollo 17 was the last manned mission to the moon. In all, 20 Apollo flights were planned but Apollo 18, 19 and 20 were canceled. But in 2007, a retired astronaut blew the whistle and claimed Apollo 18, 19 and 20 *did* happen. But they were highly classified.