Gemini 6

Delayed from its original launch date in October, Gemini 6 had been intended to be the first American space docking mission. An unmanned Agena rocket, launched ahead of Gemini 6 to serve as its docking target, had exploded during liftoff, and the October Gemini 6 mission had been scrubbed as a result. Instead, the crew of Gemini 6 – Wally Schirra and Thomas Stafford – are launched on a one-day mission to become the rendezvous target for the already-launched Gemini 7. The two manned vehicles close to within mere feet of each other – a first for human spaceflight.