Space Elevator Enthusiasts Push On despite Lengthy Time Frames and Long Odds

A space-travel technology, simple in concept, has been frustratingly difficult to realize

By David Appell

A LONG CLIMB: An artist's conception shows a climber pod ascending a space elevator's tether to deploy a satellite. Image: ISEC

SEATTLE??I think building an elevator to space is maybe the best thing I could do in the world,? Michael Laine says.

His company, Liftport, has just raised over $62,000 on Kickstarter to build robot climbers on a skyward cable?an early step toward his eventual goal of putting a space elevator on the moon. A space elevator is just what it sounds like?a capsule that travels to and from space along a track or tether to provide reliable access to orbit.

Behind Laine is the cavernous Great Gallery at Seattle's Museum of Flight, where dozens of aircraft are on display, chronicling the human adventure of flight. Meeting in a nearby conference room are about 40 space enthusiasts, in town for the annual Space Elevator Conference hosted by ISEC, the International Space Elevator Consortium. Some of them have sacrificed their careers, credit ratings or savings accounts?all in pursuit of a simple concept that has thus far proved impossible in practice.

None of the conference participants could be accused of thinking small, whether the discussion is about a 100,000-kilometer tether made of carbon nanotubes, space-based solar power, or man's ultimate destiny to seed the galaxy.

Peter Swan, retired from over 40 years building space systems and now serving as ISEC's vice president, calls a space elevator a way to ?make the human condition better.? His altruism was shared by many of the conference attendees.

But it's not all starry-eyed optimism. ?I'm trying to tackle a project that a lot of people think is science fiction,? says Laine, who has gone into foreclosure seven times over nearly a decade to keep his company, and his dream, alive. ?It's appropriate to be skeptical, even at this stage.?

UNOBTAINIUM
The idea of a space elevator has set the heart of many engineers aflutter. But all eventually run into the same obstacle?the so-called unobtainium problem, or the need for a material that does not exist.

A space elevator is a theoretical structure that reaches from the Earth's surface into space, balanced by its own mass and the outward centrifugal force from the spinning Earth. The physics is sweet?complicated enough to be interesting, simple enough to seem doable, and the space elevator?s intrigue has grown exponentially since Arthur C. Clarke gave it a fictional treatment in his 1979 novel The Fountains of Paradise.

The problem is the construction material, which must be superstrong yet very light. Equations worked out decades ago by Russian engineer Yuri Artsutanov and, independently, by American space scientist Jerome Pearson, found that the ideal tether should be tapered, widest at the geosynchronous orbit altitude of 35,800 kilometers, and narrowest at Earth's surface and at its far end. The tether should extend far past geosynchronous orbit, where a counterweight would help provide the needed tension.

The rub is that the tether must have sufficient tensile strength to hold up its own large mass. Any material works in principle, but even for stainless steel the tether would need to be 10⁴³ times wider at geosynchronous orbit than at the ground.

The only known material that offers the required strength-to-density ratio is a carbon nanotube, a cylindrical chickenwire lattice of carbon atoms. The problem is that nanotubes exist in a form akin to a pile of soot, and no one knows how to fashion them into an extended rope, braid, cable or ribbon. In the view of elevator enthusiasts, carbon nanotubes, or CNTs are the last major ?if only.?

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