By 1967, McDonnell Douglas Astronautics Company, which built the Gemini spacecraft earlier in the decade, had a contract to build several Gemini Bs for the Air Force as part of the Manned Orbiting Laboratory (MOL) program. The Gemini B would be launched atop the MOL on a Titan IIIM rocket. The Gemini astronauts would leave their spacecraft through a hatch in the heat shield of their spacecraft and travel to the MOL through a tunnel.
Like all government contractors, McDonnell Douglas was looking to expand their customer base. The company had pitched civilian versions of MOL to NASA even though NASA was planning on using Apollo hardware as the basis of future space stations. In summer 1967, McDonnell Douglas proposed a new variant of its Gemini spacecraft known as the “Big Gemini,” or “Big G.” By December 1967, the company prepared a 100-page briefing booklet for NASA with “Big G” printed on the cover. The briefing booklet made the case for a new spacecraft for NASA even though NASA was not in the market for one.
The company briefing stated, “In the 1970–1980 period, it appears that at least a dozen launches will be required for logistic purposes.” Although the Apollo Command and Service Module could service the first planned orbital workshop, which was then expected to launch in 1970, McDonnell Douglas argued that an improved and more versatile cargo vehicle would be useful for the “Orbital Workshop No. 2,” which the company expected would be launched in 1971.