In the 1960s, there were two classes of astronauts: NASA's astronauts, like those in Mercury, Gemini, and Apollo, and a top-secret United States Air Force initiative called the Manned Orbiting Laboratory. The National Reconnaissance Office just released a treasure trove of MOL documents, and it's a revealing look at an alternative past of militarized space faring.

The missile-shaped MOL would have hovered either in a sun-synchronous or polar orbit, and served as a crewed spy satellite against the Soviet Union. Astronauts would have been shuttled to and from the station on a Gemini capsule. Despite a test model launching in 1966, however, the actual station never came to fruition, and the program was cancelled in 1969.

Below is a look inside the station. It's interesting to note that one of the last corps members recruited, the heavily accomplished pilot Robert H. Lawrence Jr., would have been the first black astronaut in space. While many MOL vets went on to careers in NASA (and earned their astronaut wings), Lawrence was killed in an aircraft accident in 1967, cutting short his career.