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 1 bearing on the accident. Manned Apollo flights were suspended for 20 months while the command module's hazards were addressed. However, the development and unmanned testing of the lunar module (LM) and Saturn V Moon rocket continued. The Saturn IB launch vehicle for Apollo 1, AS-204, was used for the first LM test flight, Apollo 5. The first successful manned Apollo mission was flown by Apollo 1's backup crew on Apollo 7 in October 1968. AS-204 was to be the first manned test flight of the Apollo command and service module (CSM) to Earth orbit, launched on a Saturn IB rocket.