U.S. Air Force, Public Domain
The Manned Orbiting Laboratory (MOL) was part of the U.S. Air Force (USAF) human spaceflight program in the 1960s. The project was developed from early USAF concepts of crewed space stations as reconnaissance satellites and was a successor to the canceled Boeing X-20 Dyna-Soar military reconnaissance space plane. MOL evolved into a single-use laboratory, for which crews would be launched on 30-day missions and return to Earth using a Gemini B spacecraft derived from NASA's Gemini spacecraft.
As the 1960s progressed, the MOL competed with the Vietnam War for funds, and resultant budget cuts repeatedly caused the postponement of the first operational flight. At the same time, automated systems rapidly improved, narrowing the benefits of a crewed space platform over an automated one. A single uncrewed test flight of the Gemini B spacecraft was conducted on 3 November 1966, but the MOL was canceled in June 1969 without any crewed missions being flown. (Image Source: U.S. Air Force, Public Domain)