Questions raised anew about space elevator stability

Published 2 April 2008

As we place more systems in space — soon, perhaps, weapon platforms to counteract China’s growing anti-satellite warfare capabilities — there is a growing need to service and maintain these systems; one way to do so relatively on the cheap is to build a space elevator, but the stability of such an elevator is raising questions

As more and more assets of all types are lofted into space, and as we seriously begin to contemplate positioning weapon platforms in space both to protect our own space assets (a promise: This is the last time we use “assets” in this piece) and to attack other nations’ space systems, more thought is being given to servicing all these systems and platforms. Launching a manned space shuttle is very expensive, so creative engineers have thought up another way of getting people to space: A space elevator. The New Scientist’s David Shiga correctly points out that if an elevator stretching from Earth into space could ever be built, it could slash the cost of space travel. A controversial new study, however, suggests that building and maintaining such an elevator would be an even bigger challenge than previously thought, because it would need to include built-in thrusters to stabilize itself against dangerous vibrations. The idea behind a space elevator is straightforward — and has been around for a while: Deploy a cable stretching from the ground near Earth’s equator far enough into space, and centrifugal forces due to Earth’s spin will keep the cable taut. Vehicles could then climb up the cable, also called a tether or ribbon, to get into space, powered by lasers on the ground or other Earth-based power sources. The idea could dispense with expensive rocket launches, making access to space much cheaper.

Note that money has been pouring into studying and promoting the idea of a space elevator, and that Mountain View, California-based Spaceward Foundation has been holding an annual Space Elevator Challenge competition in which teams compete with each other over concepts and designs to thrust the elevator skyward. Trouble is, the concept has been stuck on the ground floor for decades, not least because constructing a tether strong enough for the job is beyond current technology. Nanotubes may be suitable, but they would have to be made longer and with fewer defects than any that can be fabricated today. Which brings us back to the new study, a study making the prospects appear even gloomier. Even if a space elevator could be built, it will need thrusters attached to it to prevent potentially dangerous amounts of wobbling, says Lubos Perek of the Czech Academy of Sciences’ Astronomical Institute in Prague. The addition would increase the difficulty and cost of building and maintaining