NASA’s Gemini program ran from 1964 to 1966 and the space agency regarded it as a “bridge” between the earlier Mercury project and the subsequent Apollo missions. In particular, Gemini perfected methods of spacewalking and docking spacecraft. Spurred by the Cold War Space Race with the Soviets, President John F. Kennedy had committed the U.S. to putting a man on the Moon by the end of the 1960s. Mercury and Gemini were the build-up to the fulfillment of that promise of the Apollo flights. During its 20 months and 12 missions, the Gemini program generated some superb images — read on to see 40 of them.