Along with thirteen other pilots, Chaffee was selected to be an astcapsule communicator (CAPCOM) for the Gemini 3 and Gemini 4 missions, and received his first spaceflight assignment in 1966.
Along with thirteen other pilots, Chaffee was selected to be an astronaut as part of NASA Astronaut Group 3 in 1963. He served as capsule communicator (CAPCOM) for the Gemini 3 and Gemini 4 missions, and received his first spaceflight assignment in 1966.