Still, his solution does not answer the question Bekey raised last year about the effect of oscillations that might result along the length of the tether when the ship on Earth moved. "We hadn't thought of that," Laubscher said Thursday. At this year's conference, he put out a call for people who might be interested in joining a team of people to study and solve the issue.
Other people are proposing variations on the architecture. Henson said using large pulleys to move the cables would make for an efficient and less expensive architecture. However, Shelef said that the problem with moving cables is that the moment they stop, they will get tangled together. "If you build a system that relies on constant motion to keep it alive, if it ever stops, the ribbons will touch, and then you're done," he said. He doesn't think it's realistic to imagine there would be no problems that would require operators to stop the cables.
Researchers are also learning that some of their expectations haven't proved true. For example, carbon nanotubes aren't as strong as originally though, Shelef said. Power systems for sending cars along an elevator are also trickier to design then initially thought, he said. But none of these issues is a "showstopper," he said. They just mean that once the system is built, a trip up the elevator might take a few days instead of one, he said.
The researchers will be discussing the elevator through the end of this week. On Friday, they'll hear an update on a competition spearheaded by NASA for people interested in building strong tethers that could be used in a space elevator.
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