He performed two space walks on the Gemini 10 mission in 1966 and piloted the Apollo 11 command module, which circled the Moon while the first crewed spacecraft landed there in 1969. For this important role outside the limelight of the Moon landing, he is often considered ‘the forgotten astronaut’.

Collins was a test pilot for the US Air Force before being selected as an astronaut in 1963. He retired from NASA in 1970. He was the first director of the Smithsonian Institution's National Air and Space Museum in Washington, DC, 1971–8. He was vice-president of LTV Aerospace and Defense Co. 1980–5, and founded his own company in 1985. He wrote Carrying the Fire (1974), an account of his experiences in the space programme.