Canceled Apollo missions Schirra's crew would fly the C mission, first manned CSM (Block II CSM-101, retrofitted with the cabin safety improvements) as Apollo 7 in October 1968. McDivitt's crew and mission were kept as the first manned development LM flight (D mission); this was planned to be Apollo 8 in December 1968, now using a single Saturn V launch vehicle instead of two separate Saturn IB launches. The E mission was planned as an elliptical medium Earth orbit test of the operational LM with the CSM in a simulated lunar mission to an apogee of , to be commanded by Frank Borman
Apollo 15 be selected as a prime or backup crew member for an Apollo flight; from Group 4 he was the only astronaut to make it to the Moon, with the last Apollo mission at the end of 1972. All three members of the support crew were scientist-astronauts, selected in 1967, as the prime crew felt they needed more assistance with the science than with the piloting. None of the support crew would fly during the Apollo Program, waiting until the Space Shuttle program for the chance to go into space. The three Apollo 15 astronauts had served as the backup crew