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Willem
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Canada
Dec 2001
time: 00:25
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I just came across this article in the Toronto Star:
Ladder to space
RACHEL ROSS
SEATTLE—Rockets are a violent, jarring way to leave the Earth, forcing a way past gravity with the thrusting power of a controlled chemical explosion.
But shuttles aren't the only way to go into orbit, or return.
Bradley Edwards is fleshing out plans for a calmer, efficient and economical way to get people and equipment off the ground. Instead of shooting ourselves into space, Edwards wants us to ride an elevator.
A physicist, Edwards envisions laser-powered platforms gradually rising up a long, strong cable to 100,000 kilometres from Earth's surface. He sees satellites and solar panels, astronauts and average people all taking a trip toward the stars.
The idea isn't new. It's been percolating in minds around the world for more than a hundred years. While it was made famous through the works of authors such as Arthur C. Clarke and Kim Stanley Robinson, their versions were only science fiction fantasy. The right kind of material to build the all-important cable wasn't available, not to mention other supporting technologies. But with new, strong lightweight material made with carbon nanotubes, the space elevator could be on its way up.
"Other than transporters out of Star Trek, the space elevator represents the ultimate in travel from Earth to space," believes Edwards, founder and chief technology officer of High Lift System in Seattle, Wash.
"It is a fairly simplified system ... fairly quick and flexible in terms of what you can use it for."
This is ambitious talk. But it has some blue-chip backing. NASA's Institute for Advanced Concepts (NIAC) gave Edwards a grant to develop the idea. And now there are potential rivals. Aerospace giant Lockheed-Martin last year took out a patent for technology using similar principles.
Edwards predicts an elevator would have such a dramatic effect on the price of space transportation that it would open up space for development like railways opened up the North American West.
"It's not going to cost $20 million (U.S.) to get up there. In the long term, it's conceivable that it would cost about as much as a trip around the world."
While that will still be out of range for some, it would most definitely open up space to a much larger audience. "If you cut the cost of getting into space by a factor of a thousand, you can send things you'd never considered sending up before," said Edwards.
Tourism would be the least of it.
By lowering the price to send up satellites, such systems could increase our communications ability by a factor of a thousand, Edwards believes. "Data transmission rates across the world would be improved."
Solar cells could be launched into space on satellites and used generate power for Earth, "eliminating our need to use oil, coal and nuclear power."
But first he has to build it.
Traditional rockets would carry the parts — the propulsion systems, fuel, and spools of cable — about 300 kilometres up into lower-Earth orbit. Those pieces would be put together in mid-orbit.
Assembly would be done by machines, with the help of astronauts.
The equipment's propulsion system would then send the structure another 30,000 kilometres into space. Once there, the spools would release the cable, or ribbon, as it's often called.
"Gravity will be enough to pull it down toward Earth," Edwards said. "As it is pulled down, the spools unwind and the spacecraft moves up to higher orbit. Eventually, the ribbon touches down at Earth and is anchored." The end of the line would be 100,000 kilometres from Earth.
But two spools of 8-inch ribbon won't carry much weight. So that's why Edwards would send in the "climbers." These climbers are basically identical to the platform that will ultimately carry people and things up and down, except that as each one goes up, it adds more cable to the middle. They would be powered by a laser located on the system's Earth station that would shine up at solar cells on the underside of each platform. More than 200 of the devices would make their way up to the top and never come down.
When completed, the elevator's permanent laser-powered platform would be able to lift 13 tonnes of cargo at a time. That's not as much as the 22 tonnes a space shuttle can carry, but several times more than the rockets used to send telecommunications satellites into orbit.
Tethered to its ground station, the elevator system would rotate with the Earth. That spin is important because it means the elevator could launch payloads deeper into space once they've reach the top. Think of the elevator system as your arm, and the payload as rope with a ball on the end.
If you spin the rope around your head and let it go, the ball and rope will shoot off into the air. Edwards said payload could be launched in much the same fashion, with a well-timed release.
It would be a long trip to the top though. Imagine waiting in a pod for about two weeks before reaching the space station. Edwards thinks many people would be inclined to get off after seven days, when they reached geosynchronous orbit, where you stay over the same spot on Earth. And if you were about to be flung off deeper into space, that would only be the beginning of your trip!
Like space travel now, there would be risks. Lightning could pose a serious threat to the system. If only slightly damaged, the cable could be reeled back in for repairs. "But if we got hit, there's a good chance it would sever the cable," Edwards said. And that could leave much of the project freely floating in orbit.
Edwards would tether the elevator to a base station in a region known for a general lack of lightning, to avoid trouble as much as possible. He said that they'd also be designing the system so that it's "much less conductive."
Meteor storms are another potential hazard, but Edwards has an answer for that too. He said that by tethering the elevator to a floating base station off the coast of Ecuador, he could simply move the whole thing to avoid an impending meteor shower.
"Statistically, it should survive for 200 years," he said.
The idea, at least, has already survived a century.
Russian researcher Konstantin Tsiolkovsky is thought to have originated the idea of a space elevator around 1900, though it was later thought up by researchers in the West who knew nothing of Tsiolkovsky's work. Other researchers have latched on to the idea from time to time, but a major hurdle always stood in their way: there was no material in existence that suited such a cable. The line needs to be light so it can support its own weight, but strong enough to carry several tonnes of equipment.
Until the late 1950s, all researchers had to work with was fine-gauge steel wire, ultimately too heavy to use as a space cable. In 1957, graphite whiskers were invented and a fresh crop of scientists jumped into the fray. Many proposed the idea of using an asteroid as both a counterweight and a source of carbon. The idea was they'd mine the rock — in space — for graphite and build the cable from there. As Edwards outlines in his book, The Space Elevator, this was a great idea for science fiction writers, but the real science behind the idea didn't make sense.
Asteroids weren't as ideal for graphite mining as initially thought and it turned out it would be far less expensive and time-consuming if the wire was made here on Earth.
The other problem, and it was significant, was that it would take 700,000 tonnes of graphite whiskers to make the cable strong enough. That was unreasonable, so the idea languished until the late 1990s.
Enter carbon nanotubes with their remarkable physical properties. Carbon nanotubes are long, thin tubes of carbon, like sheets of graphite rolled up into tubes. They are very strong and relatively light, compared to steel and even graphite whiskers, because of their unique molecular structure. The material was discovered in 1991, but it took a while to link this material and the space elevator concept.
Once Edwards saw the opportunities, he knew he had to pursue the space elevator idea.
Edwards is so committed that he left his job at Los Alamos National Laboratory last year to work on it full time. With help from NIAC, he set up a one-room office in downtown Seattle.
The office where the Star interviewed him is a testament to his practicality and frugality. He has one desk and three chairs. A drawing of the space elevator rests on the floor, beside a stack of books about the project.
No one could argue Edwards has blown the $570,000 grant from NIAC on frivolous office décor, but the money's running out just the same. It costs a lot to work out the details behind such a revolutionary idea. Edwards' 280-page book is packed with equations, charts and diagrams. It's a new tool for drumming up support for the project, intended to augment the in-person presentations he's given to people from around the world.
He's spoken to the European Space Agency and the United Nations, though he hasn't received a firm commitment from either yet.
The United Nations was concerned about leaving the Third World out of such a venture. But if the projects did bring down the cost of launching satellites, Edwards argues it could potentially benefit countries with less money to spend.
Edwards has also spoken to conference rooms full of scientists, who make for a difficult, skeptical audience.
"I'm sure initially there were people who came because they thought, `This will be funny. Let's go see the crackpot'." But try as they might, Edwards said, they discover no holes in his theory. Instead, they leave with a new respect for the idea.
"They tend to go from skepticism to overt support."
That overt support comes in the form of dozens of reports sent to him by experts in various fields who, after hearing Edwards' presentation, are eager to contribute their research to the project.
"We've got a couple of hundred volunteers," he said, picking up a copy of one such volunteer's statistical analysis of the tether's dynamics.
"The idea really has been embraced by the technical community worldwide," said Robert Cassanova, director of NIAC.
But despite rave reviews from the agency that provided the initial funding for the project, NASA has yet to offer any more financial support.
"The space elevator is mentioned in the long-range strategic plan for NASA," Cassanova said. And he said it's only been embraced as one possibility for the future. NASA hasn't committed to the idea yet.
Edwards figures he needs a heftier sum — $10 billion — to build the elevator. He could go to stock market for money.
But despite the obvious interest from science fiction fans, right now Edwards said he isn't comfortable with the idea of issuing public shares in the company. While it might be a good way to raise a little cash, he said he wouldn't want to play on people's hopes and dreams.
Edwards wants investors who are fully aware of the potential problems associated with a large scale, long-term project such as this one.
Even if everything went well, Edwards figures such a project is approximately 15 years away from being operational.
But that's assuming he can nail down the international relations required for such a system. "Technically, we believe it's very buildable," Edwards said. "Politics is another thing."
Especially, he said, since such a system could be used to launch military devices too.
"China might have something to say about that."
Canada is a potential participant, but nothing's panned out so far. Edwards said he has been invited to speak to the Canadian Space Agency but has been unable to make that presentation to date.
Carole Duval, a spokesperson for the agency, said it is not participating in the project "in any way" and declined to comment on the viability of such a system.
But Edwards said the Feb. 1 shuttle disaster has had an impact on his business. There's a new focus on alternatives to shuttle craft now, and it's helped him line up some new meetings with investors.
"It's still too early to tell just how much of an effect it will have," Edwards said. "My guess is it will be looked at a lot more seriously in the future."
There was a time when the idea of a trans-Atlantic cable for communications wasn't taken seriously. It was too large a project to be workable, too grandiose to be implemented. The mere idea of a cable long enough to reach across the ocean! They needed great ships to carry huge reels of cable, and that ribbon of cable just kept breaking.
But, in time, the line was laid. What had once seemed impossible was real and a technology and communications revolution was underway.
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10-02-2003 21:14
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