The cheap way to the stars - by escalator

The cheap way to the stars - by escalator
David Adam, science correspondent
Saturday September 13, 2003
The Guardian

If climbing a stairway to heaven sounds like too much hard work, then a conference of 70 scientists and engineers opening in Santa Fe today may offer hope of a more leisurely way into space.

In two days of discussions, the scientists aim to turn into a reality an ambition that has been around for at least a century: the creation of a space elevator that would deliver satellites, spacecraft and even people thousands of kilometres into space along a vertical track.

Engineers say that recent advances in materials science - particularly in the development of carbon nanotubes - mean that such a system, which first gained widespread attention when the science fiction writer Arthur C Clarke described it in his 1979 novel Fountains of Paradise, is no longer pure science fiction.

Mr Clarke - who once said a space elevator would only be built "about 50 years after everyone stops laughing" - was due to address the scientists at the Santa Fe conference today by satellite link from his home in Sri Lanka.

The American space agency Nasa is no longer laughing. It is putting several million dollars into the project under its advanced concepts programme.

At the heart of a space elevator would be a cable reaching up as far as 100,000km from the surface of the Earth. The earthbound end would be tethered to a base station, probably somewhere in the middle of the Pacific ocean. The other end would be attached to an orbiting object in space acting as a counterweight, the momentum of which would keep the cable taut and allow vehicles to climb up and down it.

A space elevator would make rockets redundant by granting cheaper access to space. At about a third of the way along the cable - 36,000km from Earth - objects take a year to complete a full orbit. If the cable's centre of gravity remained at this height, the cable would remain vertical, as satellites placed at this height are geostationary, effectively hovering over the same spot on the ground.

To build a space elevator such a geostationary satellite would be placed into orbit carrying the coiled-up cable. One weighted end of the cable would then be dropped back towards Earth, while the other would be unreeled off into space. Mechanical lifters could then climb up the cable from the ground, ferrying up satellites, space probes and eventually tourists.

The biggest technical obstacle is finding a material strong but light enough to make the cable; this is where the carbon nanotubes come in. These are microscopically thin tubes of carbon that are as strong as diamonds but flexible enough to turn into fibre. In theory, a nanotube ribbon about one metre wide and as thin as paper could support a space elevator.

No scientist has yet succeeded in making such a fibre, but Rodney Andrews, a carbon nanotube expert from the University of Kentucky will tell the conference: "Until some of the basic science concerning how to connect nanotubes together and transfer load between them in a composite is understood it will remain elusive, but a lot of progress is being made."

Brad Edwards, a space scientist who has been developing the space elevator concept for several years, said there was still a lot of scepticism to overcome. "Initially, people look at me like they're trying to work out whether or not I'm pulling their leg," he said.

Dr Edwards says the original satellite used to send up the cable should provide enough tension in the cable for the first vehicles to climb into space, each of which would then be added in turn to the counterweight. These lifters would clamp caterpillar tracks to either side of the cable and would be powered by converting laser light beamed up from the ground into electricity.

"None of it is really extravagant," said Dr Edwards, who estimates it would take about $7bn (£4.4bn) to turn the concept into reality. He hopes to have a final elevator design hammered out by next year.

He said the floating base platform would be placed hundreds of miles from aircraft routes and shipping lanes and would be in a region of the sea where storms, lightning and high waves are rare.

The biggest hazard could be space junk, but Dr Edwards said the floating platform would be moved around to steer the cable out of the way. He says it would slash the price of access to space 400-fold, and could allow cheaper, faster travel to other planets.

One unlikely problem could be capturing the public's imagination. "When we actually start launching this it's going to be kind of boring," Dr Edwards said. "There's no smoke, there's no pillars of fire and there's no loud rumbling noises. There's just this thing that slowly ascends the ribbon into space."