Apollo 8 yet ready to make its first flight. Astronaut Jim McDivitt's crew, who were training to fly the first lunar module flight in low Earth orbit, became the crew for the Apollo 9 mission, and Borman's crew were moved to the Apollo 8 mission. This left Borman's crew with two to three months' less training and preparation time than originally planned, and replaced the planned lunar module training with translunar navigation training. Apollo 8 took 68 hours (almost three days) to travel the distance to the Moon. The crew orbited the Moon ten times over the course of 20 hours, during
Apollo 4 NASA in the Apollo spacecraft, also built by North American. The mission was the first Apollo flight after the stand-down imposed after the Apollo 1 fire which killed the first Apollo crew. It was the first to use NASA's official Apollo numbering scheme established in April 1967, designated Apollo 4 because there had been three previous unmanned Apollo/Saturn flights in 1966, using the Saturn IB launch vehicle. The mission lasted almost nine hours, splashing down in the Pacific Ocean, achieving all mission goals. NASA deemed the mission a complete success, because it proved the Saturn V worked, an important step