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Is the Final Frontier Just One Ride Away On a Space Elevator?
By Lee Gomes
The Wall Street Journal - August 22, 2007
Tie a rock to the end of a piece of ribbon, then spin it over your head. It will be pulled taut as the rock circles about. Now, imagine a ribbon 62,000 miles long, anchored near the equator with a weight on the other end. The centrifugal force of the earth's rotation will make it behave the same way. You'll end up with not only the world's biggest nunchuck, but also a kind of elevator to outer space.
A space elevator is one of those ideas from 1950s-style futurism that
are so wacky they might just work. A thriving community of elevator
buffs certainly thinks so; they meet online at sites like
spaceelevator.com.
NASA is sufficiently intrigued that it has kicked in millions of dollars
for a space-elevator design competition. The third annual running of the
contest takes place in October outside of Salt Lake City; 22 teams,
mostly from universities, have signed up to compete.
To the extent that a space elevator is feasible at all is due to
advances in the science of nanotechnology, especially carbon nanotubes.
These are atomic-scale threads with a tensile strength greater than
steel but with vastly less weight; when bound together, they become
unimaginably strong.
The long spine of the proposed elevator would be 30 inches wide but only
as thick as a sheet of paper. Wade Adams, a nanotech researcher at Rice
University, said nano engineers have created threads 15% as strong as
those needed for an elevator, and continue to make steady progress.
Existing nanotube threads are already triple the strength of the Kevlar
strands used in bulletproof vests.
The main theorist of the space elevator is Brad Edwards, a former Los
Alamos National Lab physicist who spent three years under a NASA
contract figuring out if a working elevator could be built. Yes, he
concluded, and here's how:
A rocket would take two spools, each the size of a living room with
31,000 miles of ribbon wrapped around it, to an orbit of 22,000 miles.
Both would be unrolled, one being allowed to waft back to earth, the
other pulled up and away from earth by a spacecraft and then anchored
with a weight at the end. Then they'd be joined in the middle.
The bottom portion would be secured onto an oil rig-like platform
located along the equator, 1,500 miles west of Mexico, a location chosen
for its uneventful weather.
The ribbon would weigh 800 tons, or about 26 pounds a mile. Were it to
break, the top segment would float away into space while the bottom
would fall to earth. Nothing you'd want to be on hand to see, of course,
"but nothing that would threaten the planet," says Dr. Edwards.
The actual cab of the elevator -- the "climber" -- would attach to the
ribbon via rollers. It would zip up at 120 miles an hour, requiring a
week to reach the very top. While there's nothing but deadly space
radiation to keep people from making the trip, the elevator is mostly
conceived as an all-cargo affair, especially for satellites.
Remarkably, it could also be used for trips to the moon, Mars or beyond.
Recall, says Dr. Edwards, that the earth rotates once every 24 hours,
meaning that something tethered to it 62,000 miles up travels at more
than 20,000 miles an hour. If you're at the top of the elevator and time
it right when you let go, you can be whipped to just about anywhere you
want to go, with a nudge or two from booster rockets.
The teams at the October event will be entering a miniature version of a
climber that will need to go up and down a 400-foot tether. To win the
$1 million prize, a climber has to make the trip within a specified
time. Last year, a team from the University of Saskatchewan (this year,
five of the 22 entries are from Canada) came within 0.04 second of
winning.
Climbers, in general, get their power from the ground. Last year, the
Saskatchewan team members aimed powerful light beams at their climber,
which then used solar panels to convert the light into electricity. This
year, says captain Clayton Ruszkowski, they're switching from light
beams to lasers that are a million times as strong as the one in your
DVD drive. Back east in Cambridge, Mass., the MIT team is working on a
climber that will work on beamed-up microwave energy.
Dr. Edwards estimates a real elevator would cost $12 billion and could
pay for its operations by capturing 25% of the commercial
satellite-launching.
As for NASA, says Dr. Edwards, it's committed to the contest not
necessarily because it's sold on the idea, but because it's interested
in the sort of spinoff technologies that elevator research might make
possible, such as for advanced composite materials that might be used in
other spacecraft.
Another use of the space elevator contest is to get schoolchildren
interested in something besides their iPods. Diana Jennings, associate
director of the Institute for Advanced Concepts, a NASA-funded outfit
sponsoring the contest, says young eyes light up when she talks about
the elevator.
Not even the space shuttle elicits that reaction. "Everything else is
just TV for them now," she says.
(License this article from Dow Jones Reprint Service)
For more information about NASA and other agency programs, visit:
http://www.nasa.gov
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