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
Apollo 7 Apollo 7 Apollo 7 was an October 1968 human spaceflight mission carried out by the United States. It was the first mission in the United States' Apollo program to carry a crew into space. It was also the first U.S. spaceflight to carry astronauts since the flight of Gemini XII in November 1966. The AS-204 mission, also known as "Apollo 1", was intended to be the first manned flight of the Apollo program. It was scheduled to launch in February 1967, but a fire in the cabin during a January 1967 test killed the crew. Manned flights were then suspended