Canceled Apollo missions planning their own circumlunar flight for December to upstage the Americans once again (see Zond program). McDivitt's crew—who had grown accustomed to working with LM-3 and preparing for its flight—was kept on the D mission which now became Apollo 9, while Borman's crew would fly the CSM lunar orbit mission on Apollo 8, and the E mission was canceled. The swap of crews was also decisive in who would be the first man to walk on the Moon. Pete Conrad was backup Commander for McDivitt's crew, and by the process of crew rotation, would have been in line for Commander
Apollo 1 the prime crew for a second Block I CSM flight, AS-205. NASA planned to follow this with an unmanned test flight of the LM (AS-206), then the third manned mission would be a dual flight designated AS-278 (or AS-207/208), in which AS-207 would launch the first manned Block II CSM, which would then rendezvous and dock with the LM launched unmanned on AS-208. In March, NASA was studying the possibility of flying the first Apollo mission as a joint space rendezvous with the final Project Gemini mission, Gemini 12 in November 1966. But by May, delays in making Apollo ready