GRAPHIC: SPACE ELEVATOR

Ever since it was first popularised by Arthur C Clarke, the idea of a “space elevator” has languished in the realms of science fiction. But now a team of British scientists has taken the first step on what could be a high-tech stairway to heaven.

Spurred on by a $4m (£2.7m) research prize from Nasa, a team at Cambridge University has created the world’s strongest ribbon: a cylindrical strand of carbon that combines lightweight flexibility with incredible strength and has the potential to stretch vast distances. The development has been seized upon by the space scientists, who believe the technology could allow astronauts to travel into space via a cable thousands of miles long — a space elevator.

They predict the breakthrough will revolutionise space travel. It has a point, though at this stage it is still a tenuous one. Such an elevator could potentially offer limitless and cheap space travel. At a stroke, it would make everything from tourism to more ambitious expeditions to Mars commercially viable. The idea couldn’t come too soon for Nasa, which spends an estimated £308m every time the shuttle blasts off, not to mention burning about 900 tons of polluting rocket fuel.

The American space agency is already staring at a black hole in its finances that means it will not replace its ageing shuttle fleet — due to retire in 2010 — until 2014 at the earliest. Without its own transport, Nasa has recently contracted private firms such as SpaceX, headed by Elon Musk, the internet entrepreneur, to provide transport to and from the International Space Station. The idea of an elevator could solve the problem — although perhaps not quickly enough for Nasa.

The Cambridge team is making about 1 gram of the high-tech material per day, enough to stretch to 18 miles in length. “We have Nasa on the phone asking for 144,000 miles of the stuff, but there is a difference between what can be achieved in a lab and on an industrial level,” says Alan Windle, professor of materials science at Cambridge University, who is anxious not to let the work get ahead of itself.

Enthusiasts say space elevators will be able to lift material more than 22,000 miles into orbit for as little as £300 per pound weight, compared with about £14,000 per pound using existing rockets. That would open up the possibility of tourists visiting a sky hotel in orbit, with a view previously enjoyed only by astronauts. It would also allow for far cheaper travel to the moon and planets since most of the energy required by rockets is used simply to escape Earth’s gravity.

The concept of a lift into space was first proposed in 1895 by Konstantin Tsiolkovsky, a Russian scientist who was inspired by the Eiffel tower. The idea continued to be batted around in scientific circles until the late 1970s when Clarke based his novel The Fountains of Paradise on the idea. In it he asked: “If the laws of celestial mechanics make it possible for an object to stay fixed in the sky, might it not be possible to lower a cable down to the surface and so establish an elevator system linking Earth to space?”

At the time the answer was a resounding “no”, and Clarke admitted the idea would be met with laughter for years to come, but over the past decade the concept has moved from the fringes of the scientific establishment towards the mainstream.

The theory sounds plausible: a cable is extended up to a station 22,245 miles into space — the point at which satellites stay in geostationary orbit — and kept under tension by the competing forces of gravity on Earth and the outward centrifugal acceleration at the platform end. The cable then extends a further 40,000 miles into space to a counterweight that helps keep the whole structure stable. An elevator is attached and powered up the cable much like a train on a celestial track.

The idea is still in the realms of science fiction, and no one is expecting it to become a reality for at least another decade, but the concept is gaining currency. Last year saw the formation of the International Space Elevator Consortium, an independent group designed to promote the idea.

Nasa has pledged $4m over five years from its Centennial Challenges programme to the Elevator: 2010 competition. The contest challenges teams to build working scale models of an elevator that can travel 1km vertically upwards at a minimum speed of 2 metres per second. The best performance so far is just 100 metres at a speed of 1.8 metres per second. The next challenge is scheduled for April.

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