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Thomas Stafford was Schirra's co-astronaut during the Gemini 6A mission. This mission, launched on December 15, 1965, was a significant step in NASA's Gemini program, marking the first successful space rendezvous. Stafford and Schirra skillfully maneuvered their spacecraft, Gemini 6A, to rendezvous with Gemini 7, which had been in orbit for several days.