Project Orion has to be the most audacious, dangerous and downright absurd space programme ever funded by the US taxpayer. This 1950s design involved exploding nuclear bombs behind a spacecraft the size of the Empire State Building to propel it through space. The Orion’s engine would generate enormous amounts of energy – and with it lethal doses of radiation.

Plans suggested the spacecraft could take off from Earth and travel to Mars and back in just three months. The quickest flight using conventional rockets and the right planetary alignment is 18 months.

There were obvious challenges – from irradiating the crew and the launch site, to the disruption caused by the electromagnetic pulse, plus the dangers of a catastrophic nuclear accident taking out a sizable portion of the US. But the plan was, nevertheless, given serious consideration. Project Orion was conceived when atmospheric nuclear tests were commonplace and the power of the atom promised us all a bright new tomorrow. Or oblivion. Life was simpler then.

In the early 1960s, common sense prevailed and the project was abandoned, but the idea of nuclear-powered spaceships has never gone away. In fact there are several in the cold depths of space right now.