Manned Orbiting Laboratory

The Manned Orbiting Laboratory (MOL), originally referred to as the Manned Orbital Laboratory, was part of the United States Air Force's manned spaceflight program, a successor to the cancelled Boeing X-20 Dyna-Soar military reconnaissance space plane project. The project was developed from several early Air Force and NASA concepts of manned space stations to be used for reconnaissance purposes. MOL evolved into a single-use laboratory, with which crews would be launched on 40-day missions and return to Earth using a Gemini B spacecraft, derived from NASA's Project Gemini.

The MOL program was announced to the public on 10 December 1963 as a manned platform to prove the utility of man in space for military missions. Astronauts selected for the program were later told of the reconnaissance mission for the program. The contractor for the MOL was the Douglas Aircraft Company. The Gemini B was externally similar to NASA's Gemini spacecraft, although it underwent several modifications, including the addition of a circular hatch through the heat shield, which allowed passage between the spacecraft and the laboratory.