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
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