To build a space elevator, you'll need a very light car and a very strong string.
- By Michael Milstein
- Air & Space magazine, March 2006
(Page 3 of 6)
Daily elevator departures would make expensive and risky rocket launches obsolete. Costs of lofting satellites could fall substantially, making communications and everything else that depends on them far cheaper. With many more people able to afford it, space tourism would become truly practical. Or so elevator champions, like Bradley Edwards, believe.
Edwards attended the elevator challenge not to compete but to cheerlead. He first got curious about the space elevator as a physicist at Los Alamos National Laboratories in New Mexico after hearing the naysayers proclaim it would never work. The technology conronts many dangers, and Edwards has heard them all. What happens, for example, if the elevator cable collides with something in orbit? About 100,000 pieces of debris big enough to sever a cable speed around Earth. Space junk is so plentiful that a piece could slice through the cable roughly every 250 days. Such a catastrophe would leave anything above the break careening through space, and anything lower falling in a fiery reentry toward the planet.
Edwards has a plan to avoid this. First, the cable would be designed to withstand impacts. Instead of a single strand, the cord would consist of a flat ribbon of nanotube fibers lined up side by side and reinforced at intervals by horizontal strips of high-strength tape. If a speeding meteorite cut through a few fibers, the tape above and below the break would hold the rest tight and shift the load onto adjoining fibers. Also, the flat bundle of fibers would have a slight curve to it, so a small meteorite that hit it sideways would not slash through all the fibers.
A robust system to track orbiting debris, Edwards notes, would spot anything endangering the elevator and alert the ship or floating platform at the base of the cable to steer clear. A mile or two of movement ought to be enough to dodge the dangers, Edwards estimates.
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.