Until now the astronauts knew, in the back of their minds, there was a possibility that a malfunction would turn this countdown into just another practice run and they would have to get out and try again another day. But, as the count reached T minus 15 minutes, there was no doubt, they were really going.
For now the mighty Saturn V stood empty. But overnight, even while Borman’s crew slept, technicians would ready it for departure. By morning its enormous fuel thanks would be filled with cryogenic propellants, until the rocket would contain the explosive energy of an atomic bomb.
Perhaps the most significant point about the lunar-orbit flight proposed for Apollo 8 was that the command and service modules would fly the same route to the moon as would be used for the actual lunar landing.
An ‘A’ type mission would be flown with a Saturn V and be used to test the Launch vehicle, spacecraft, and a high velocity lunar return. Nasa cover the ‘A’ mission with Apollo 4 & 6.
A ‘B’ type mission would be flow with a Saturn IB and test the lunar module development, and propulsion, and launch vehicle staging. This was accomplished with Apollo 5.
A ‘C’ type mission would be flown with a Saturn IB and test the command and service module and evaluate the crew performance in low earth orbit. This was accomplished with Apollo 7…