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
Return of Apollo 15 to Earth which was launched using a spring-loaded mechanism, a pin in a curved groove to impart a spin in the satellite. The spinning helped to stabilise the craft. After having the information needed to burn the SPS to send them home radioed from Mission Control, "Apollo 15" disappeared behind the Moon for the last time. Igniting on time, the SPS burned for 2 minutes, 21 seconds, adding 3,050 ft/s (930 m/s) to their speed. Little was left for the crew to do on their tenth day in space. They continued to photograph the lunar surface as it receded from them, using