Set in a future 1970, the United States is considering building bases on the Moon. Colonel Briteis, Major Bill Moore, and Doctor Wernher are sent to orbit the Moon to survey landing sites for future lunar missions. However, Dr. Wernher is an impostor whose mission is to destroy the US's Earth-orbiting space station, which he plans to do by colliding the rocket with the station on the way back from the Moon.
While on the way out, however, Wernher inadvertently gives his identity away. In the ensuing struggle for the control of the rocket, Col. Briteis has to make an emergency landing on the Moon. With them all marooned, Dr. Wernher redeems himself by helping establish communications with Earth, although an accident results in his untimely death. In response to the unexpected turn of events, the US authorities decide to make the immobilized spaceship the core of a new moon base. To avoid a scandal, their commander, General Greene, cajoles Major Moore into proposing to Colonel Briteis (so as not to have an unmarried male and female astronaut alone in close quarters for weeks). Briteis accepts, but requests that Major Moore be promoted to Brigadier General after they are married so that he will outrank her
- Originally intended as a pilot film for a TV series to be called Ring Around the Moon. When science-fiction movies started to become popular, producer Jack Seaman added enough footage to the film to bring it up to feature length. This was done without the knowledge of writer Robert A. Heinlein, who disowned the result.
- This movie and Cat-Women of the Moon (1953) were made using some of the same sets and costumes and were released within one day of each other. Both use spacesuits from Destination Moon (1950), but Project Moon Base added new helmets.