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 17 backup crew of Apollo 14) would become prime crew of the mission. NASA Director of Flight Crew Operations Deke Slayton ultimately assigned the backup crew of Apollo 14 (Cernan and Evans), along with Schmitt, to the prime crew of Apollo 17. The Apollo 15 prime crew received the backup assignment since this was to be the last lunar mission and the backup crew would not rotate to another mission. However, when the Apollo 15 postage stamp incident became public in early 1972 the crew was reprimanded by NASA and the United States Air Force (they were active duty officers). Director