He is one of 24 people to have flown to the Moon. Collins was the fourth person, and third American, to perform an EVA; and is the first person to have performed more than one EVA.
In late June 1965, Collins received his first crew assignment, the backup pilot for Gemini 7. His first spaceflight was on Gemini 10, in which he and Command Pilot John Young performed two rendezvous with different spacecraft and Collins undertook two extra-vehicular activities (EVAs).
His second spaceflight was as the Command Module Pilot for Apollo 11. While he stayed in orbit around the Moon, Neil Armstrong and Buzz Aldrin left in the Lunar Module to make the first manned landing on its surface.