Every jaded space nerd has a dream of where they hoped space exploration would take us. By now I imagined the Earth would be circled by gleaming space hotels, flights to the Moon would be routine and the first settlers would be colonising the dusty plains of Mars.

As yet, despite Richard Branson’s best efforts, our glittering space future remains as elusive as ever. Although, only the other week, a man in a gorilla suit chased a British astronaut through a space station. So it’s not all bad.

For the last 40 years, human progress beyond Earth’s orbit has been painfully slow, with space history littered with hundreds of abandoned projects and concepts. But an alternate and very different pattern of space exploration might have become reality had a few Cold War missions been given the final go-ahead.

Nuclear rocket

On the grey concrete of a small outdoor display area at Nasa’s Marshall Space Flight Center in Alabama sits one of the most unusual engines the agency has ever developed. Mounted on a frame alongside a long thin Space Shuttle solid rocket booster (with “empty” reassuringly painted on the side), the funnel-shaped Nerva engine was designed to take astronauts to Mars.