Setting the ground work (so to speak) for the International Space Station and future space walkers, the rendezvous between Gemini 6 and Gemini 7 in December 1965 marked the first time two crafts met in space.

 

According to NASA, this photograph — taken by Gemini VI crewmembers Walter Schirra and Thomas Stafford — shows Gemini VII in orbit 160 miles above Earth. Gemini 7 also studied the long-term effects of space on the two-man crew.