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Going Up?

To build a space elevator, you'll need a very light car and a very strong string.

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If the materials and money are available, advocates argue that no law of physics prevents an elevator from working. Then again, you could have said the same about building a robot able to climb a rope.

Some of the machines that competed in the challenge resembled assemblies of Erector Sets, while others looked like they could stop a tank. Brian Pierce and his teammates spent more than a year constructing their climber from an extra wheelchair frame that team leader Vincent Lopresti had in his closet in Texas. They sold T-shirts and coffee mugs to raise money for parts and hit up companies such as Dremel for tools and Sunrise Medical, a medical supply company, for the solar cells. The team scavenged the motor from a kid’s Mongoose scooter, and tension springs from a Chevy carburetor.

For Lopresti, 40, the competition signaled that space is finally open to the public, and he wanted in. A software-designer-turned-engineer who thinks his home near Dallas would make a good spaceport, he grew so obsessed with the space elevator he couldn’t think about much else. He turned designs over and over in his head. “It’s almost like a kid in a candy store; there are so many different options,” he said. “I have all kinds of junk in my house, and it just all started falling together.”

Their climber evolved into a kind of sideways wheelchair with a motor on one side and a solar panel as a counterbalance on the other. Lopresti foresees an extraterrestrial gold rush as a space elevator opens the door to mining moons and planets and collecting and recycling satellites that have gone kaput.

“I’m going to do what I can to make sure that happens,” said Lopresti, zipping around in his wheelchair at an industrial park in Mountain View, California, where teams tuned up their climbers before the competition. It was tense as competitors sized up opponents they’d face the next day. Some worked through the night, struggling with last-minute fixes.

The trouble they all ran into was one that has always dogged spacefarers: Lifting even a pretty small craft takes a lot of power. That’s especially true when relying on solar panels, which capture only a small slice of energy from light falling on them. Even the industrial searchlight provided for the contest, as bright as it was, did not generate much juice.

Lopresti’s climber, Space Miner, wouldn’t budge. “We cut off all the extra things, but it’s still 70 freaking pounds,” an exasperated Pierce
declared.

Other teams tried novel ways to wring power from the light. Engineer Matthew Abrams arrived from Maryland with his climber in suitcases bearing duct-tape labels that said “Robot parts—fragile.” When he got it together, a reflective dome focused light on a water-filled canister.

The plan was for the water to heat up, producing pressure to drive a piston that would yank the climber up the strap. But the water hit only 150 degrees instead of the 300-plus Abrams needed.

“That’s all?” Abrams asked in disbelief, watching a thermometer tick off the degrees much too slowly. “We’re screwed.”

About Michael Milstein

Michael Milstein is a freelance writer who specializes in science. He lives in Portland, Oregon.

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