The Manned Orbiting Laboratory was a US Air Force initiative to build a space station in Earth orbit for surveillance and research purposes.
It would have used Gemini capsules to deliver pairs of Air Force astronauts for missions lasting up to 4 weeks, but funding problems, particularly competition from the Apollo programme and the Vietnam war, eventually scuttled the programme.
Deeper background:
“The Best Laid Plans: A History of the Manned Orbiting Laboratory” a history provided by the Aerospace Corporation.
Some of the equipment is on display at the Air Force Museum.
Photo: US Air Force