Spaceflight is dangerous. Everyone knew that. None more so than the astronauts, their families, and all those intimately involved in Apollo – the project to land a man on the Moon. On that evening, 20 July 1969, everyone in Mission Control in Houston knew the danger. The lives of the two men about to attempt a descent to the lunar surface depended upon single moments, the single decision any of them might have to make in a second.