OF THE 12 men who walked on the moon, only four are alive today, following the death of Apollo 12 astronaut Alan Bean last month. At the time of the Apollo programme, it was widely expected that NASA would have sent people to Mars and even the rest of the solar system by now.

Instead, those few moon landings are fading into the distant past. What went wrong?

For starters, NASA can’t agree on a destination. There are two vociferous factions in the agency: one …