Space.com: The U.S. Air Force's MOL program ran from December 1963 until its cancellation in June 1969. The program spent $1.56 billion during that time, according to some estimates. by Leonard David
'While the program never actually lofted a crewed space station, those nearly six years were quite eventful, featuring the selection of 17 MOL astronauts, the remodeling of NASA's two-seat Gemini spacecraft, the development of the Titan-3C launch vehicle and the building of an MOL launch site at Vandenberg Air Force Base in California.
'In the end, the death of MOL provided Abrahamson a lesson he has applied to other programs. "If you can just get an empty can up there … do it. Because then, you can build on it," he said.
'The strategy with the Congress, "not the technical challenge," was the biggest risk, Abrahamson said.
'According to Outzen, the reconnaissance historian, "There is often a misplaced assumption that a canceled program has no important legacy. This should not be said of the Manned Orbiting Laboratory program."'
Declassified docs here