Modern thinking about space elevators dates back to 1895 when Russian school teacher Konstantin Tsiolkovsky was inspired by the recently completed Eiffel Tower in Paris to consider the physics of building a tower all the way to space so that spacecraft could be launched into orbit without rockets. Science fiction writer Arthur C Clarke inspired more recent interest with his 1979 novel The Fountains of Paradise in which his main character builds a space elevator with a similar design to those being investigated today.

But how do you make it reality? “I love the outrageousness of the idea,” says Kevin Fong, who founded the Centre for Altitude, Space and Extreme environment medicine at University College London. “I can see why people have their eyes on the concept because if you can get to low Earth orbit cheaply and safely then the inner Solar System becomes your oyster.”

Safety issues



The sticking point is how you would actually build it. “To begin with it would need to be made of an as yet non-existent extremely strong yet flexible material with the right mass and density characteristics to support the vehicles, and capable of withstanding an incredible array of sheering forces,” says Fong. “I would imagine it would require the most ambitious series of low- and high-Earth orbital missions and space walks in the history of our species.”

Then there are the safety issues, he adds. “Even if we could overcome the considerable engineering challenges involved in building this thing, it paints a rather terrifying picture of a giant cheese wire scything through space taking out space vehicles and being itself hit by all the space debris already up there.”

There have been three detailed concept designs published in the last 12 years. The first, published by Brad Edwards and Eric Westling in their 2003 book Space Elevators, envisaged 20-tonne payloads powered by Earth-based lasers travelling at a cost of $150 a kilogram, and with a construction price tag of $6bn (£3.9bn).