Apollo 11 the CMP on the Apollo 8 crew, began experiencing trouble with his legs. Doctors diagnosed the problem as a bony growth between his fifth and sixth vertebrae, requiring surgery. Lovell took his place on the Apollo 8 crew, and, when Collins recovered, he joined Armstrong's crew as CMP. In the meantime, Fred Haise filled in as backup LMP, and Aldrin as backup CMP for Apollo 8. Apollo 11 was the second all-veteran crew on an American mission, the first being that of Apollo 10. The next was STS-26 in 1988. The backup crew consisted of Lovell as Commander, William Anders
Journey of Apollo 15 to the Moon so that there was even heat distribution. Nearly 15 hours after launch, the crew switched off the lights in the cabin and went to sleep. The second day of Apollo 15 centered around the second planned midcourse correction and a preliminary check of the Lunar Module, "Falcon". Mission Control first got the crew to perform a 0.7 second burn of the SPS engine before the planned second course correction. This was designed to isolate the location of the short in the Delta-V Thrust switch. The burn allowed Mission Control to confirm that the SPS would only be ignited accidentally if