Apollo 9 in early 1969. However, LM problems again prevented it from being ready for the D mission by December, so NASA officials created another mission for Apollo 8 using the Saturn V to launch only the CSM on the first crewed flight to orbit the Moon, and the E mission was cancelled as unnecessary. Slayton asked McDivitt and Borman which mission they preferred to fly; McDivitt wanted to fly the LM, while Borman volunteered for the pioneering lunar flight. Therefore, Slayton swapped the crews, and McDivitt's crew flew Apollo 9. The crew swap also affected who would be the first crew
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.