<P> Of the twenty - four astronauts who flew to the Moon, two went on to command a Skylab mission, one commanded Apollo--Soyuz, one flew as commander for Approach and Landing Tests of the Space Shuttle, and two went on to command orbital Space Shuttle missions . A total of twenty - four NASA astronauts from the Apollo era flew on the Space Shuttle . </P> <P> NASA's Director of Flight Crew Operations during the Gemini and Apollo programs was Donald K. "Deke" Slayton, one of the original Mercury Seven astronauts, who was medically grounded in September 1962 due to a minor cardiac arrythmia--paroxysmal atrial fibrillation . Slayton was responsible for making all Gemini and Apollo crew assignments . In March 1972, Slayton was restored to flight status, and flew on the 1975 Apollo--Soyuz Test Project mission . </P> <P> The prime crew members selected for actual missions are here grouped by their NASA astronaut selection groups, and within each group in the order selected for flight . </P> <Ul> <Li> Virgil I. "Gus" Grissom--Pilot of Liberty Bell 7 and commander of the first manned Gemini 3, Grissom was selected in 1966 to command the first manned mission, Apollo 1, a low Earth orbit test of the Apollo Command / Service Module . This mission ended a month before its scheduled launch, when a cabin fire on the launch pad killed Grissom and his entire crew--Ed White and Roger Chaffee--on January 27, 1967 . According to Slayton, Grissom would have been his choice to be the first to walk on the Moon . </Li> <Li> Walter M. Schirra Jr .--Pilot of Sigma 7 and commander of Gemini 6A, was selected to command a second CSM test flight which was canceled in late 1966, at which time he was reassigned as Grissom's backup . Twenty - one months after the Apollo 1 fire, Schirra commanded the first CSM test flight, Apollo 7 . He was the only member of the "Mercury Seven" to fly on all three programs . </Li> <Li> Alan B. Shepard Jr .--America's first man in space on Freedom 7 was originally selected to command Gemini 3, but was medically grounded for the duration of Gemini due to Ménière's disease and assisted Slayton in Flight Operations . After corrective surgery, Shepard was restored to flight status and commanded Apollo 14, the third successful Moon landing mission . </Li> </Ul>

Who were the astronauts that went to the moon