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 16 With the assistance of orbital photography obtained on the Apollo 14 mission, the Descartes site was determined to be safe enough for a manned landing. The specific landing site was between two young impact craters, North Ray and South Ray craters – in diameter, respectively – which provided "natural drill holes" which penetrated through the lunar regolith at the site, thus leaving exposed bedrock that could be sampled by the crew. After selecting the landing site for Apollo 16, sampling the Descartes and Cayley formations, two geologic units of the lunar highlands, was determined by mission planners to be the