He flew two Gemini missions in 1965–6, became the third man on the Moon on Apollo 12, which he commanded in 1969, and commanded the first Skylab space station mission in May 1973. During this mission he made a heroic space walk to save the project by freeing a jammed solar panel.
Conrad's Gemini 5 flight established a space endurance record, and he commanded Gemini 12 to a world altitude record. He was selected as an astronaut in 1962, left NASA in 1973, and later became a vice-president of the McDonnell Douglas aircraft company.