Will we ever return to the moon, and if the Apollo missions had not been cancelled, where would we be now? (Image: NASA)

IT IS 14 December 1972. Eugene Cernan and Harrison Schmitt climb back aboard Apollo 17’s lunar module. Just three years after Neil Armstrong’s historic step, human exploration of the moon is coming to an end.

The die had been cast years before Apollo 11 had even reached the moon. In the late 1960s, the Vietnam war was straining US finances. A fatal fire on the Apollo launch pad in January 1967 had blotted NASA’s copybook. The Soviet moon effort seemed to be going nowhere. In the budget debates during the summer of 1967, Congress refused NASA’s request to fund an extended moon programme.

What if things had been different that summer? Suppose Congress had granted NASA’s wish, then fast-forward 40-odd years…

It’s July 2009, and in Johnson City, America’s permanent colony on the moon – named after Lyndon B. Johnson, the president who authorised it – they are celebrating the third generation of lunar Americans: the first child born to parents themselves born on the moon. With just 5000 inhabitants, “city” is perhaps too grandiose a term. Those who had anticipated a domed city of the kind that once graced science fiction comics had also been disappointed. That idea never stood up to the harsh lunar reality of cosmic rays and meteorite bombardment.

Fortunately, there was a ready-made alternative: subsurface lava tubes carved by extinct volcanic flows. The early Apollo missions had seen evidence for partly collapsed tubes in the form of intermittent surface trenches. The extreme …