Just a few minutes after Apollo 8’s second TV broadcast, Borman, Lovell, and Anders passed Earth’s gravitational hill top and crossed into the Moon’s gravitational sphere of influence.
At T plus 40 seconds Apollo 8 went supersonic and the ride smoothed out. Now it was quite again, but Borman kept a watchful eye on the trajectory readouts. If there was a Saturn malfunction he could whisk the capsule away just by twisting the abort handle. This would trigger the escape rocket.
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.