Posted on 09/17/2003 12:42:46 PM PDT by LibWhacker
SANTA FE, New Mexico -- No matter how you view it, a space elevator is a stretch not only of vision, but also of far-out materials and cutting-edge technology.
Putting in place a space elevator is complicated: Extend a super-strong ribbon from an Earth-situated platform at the equator out beyond geosynchronous orbit. Once in position, electric lifts clamped to the ribbon would truck spacecraft, science gear, as well as passenger-carrying modules into space.
But the quest for a revolutionary route to space is getting very real. So real, in truth, that the specter of a terrorist attack on such a stellar skyscraper cant be discounted. Nor can a host of thorny national and international legal and policy qualms be set aside for too long.
Those were among numerous issues addressed during the 2nd Annual International Conference on the Space Elevator, held here September 12-15. The event was co-sponsored by the Los Alamos National Laboratory of Los Alamos, New Mexico and the Institute for Scientific Research, Inc., based in Fairmont, West Virginia.
Mass exodus
No longer merely theoretical, research and development dollars are actually being spent on fleshing out how best to build these sky high beasts of burden.
The Institute for Scientific Research (ISR), a recently formed independent organization staffed with a cadre of multidisciplinary scientists, engineers, mathematicians, and other specialists, is currently shouldering most of the work on the space elevator project. A core ISR business area is in energy and space.
Preliminary studies of the space elevator suggest that it would be capable of lifting 5-ton payloads every day to all Earth orbits, the Moon, Mars, Venus or the asteroids. Furthermore, it could be operational in 15 years.
Now projected to be on the order of a $6 billion investment, the first space elevator could quickly reduce lift costs to $100 per pound. That far outstrips todays pricey launch costs of roughly $10,000 to $40,000 per pound, depending upon destination and choice of rocket launch system.
Better yet is the offering from follow-on and larger elevators, built-to-order by making use of the initial one. Lift ticket expenses drop ever more sharply, permitting large-scale use of space, be it for commercial, military, scientific purposes, or even the mass exodus of space settlers.
Economy of scale
"With the space elevator were going to reduce the cost, difficulty, and complexity of going into space," said Bradley Edwards, Director of Research for ISR. "With this technology, it would have a lot fewer critical parts than todays space shuttle," he added, perhaps making it far safer to access space.
"This is a different technology than rockets," Edwards told SPACE.com. "Whether youre going into Earth orbit, to the Moon, Mars, Venus, the asteroidsthe space elevator is really the way to go," he said.
Theres a key problem with rockets, said Bryan Laubscher of the Los Alamos Space Instrumentation and System Engineering Group.
"Rockets are not a technology subject to the economy of scale. Therefore, theyll never be cheap. The space elevator is subject to the economy of scale and opens up the possibility of truly inexpensive access to space," Laubscher said.
As this years conference organizer, Laubscher said that the space elevator "is a paradigm shift from the way we get into space now."
The NASA (news - web sites) Institute for Advanced Concepts (NIAC) recognized early the space elevators revolutionary potential, awarding Edwards research monies to hammer out technical details of the idea, prior to his joining ISR.
Patricia Russell, NIAC Associate Director, advised those at the conference to keep a NIAC credo in the forefront of deliberations, no matter how daunting the road ahead.
"Dont let your preoccupation with reality stifle your imagination," Russell said.
Laughing has stopped
Science fiction sage, Sir Arthur Clarke, beamed in his support for the elevator project via satellite from Sri Lanka. In technical papers and particularly in his novel, The Fountains of Paradise, Clarke has backed the creation of a space elevator.
"I do think it may be the way to space. The economics are fantastic," Clarke advised conference listeners. Space tourism, microgravity materials processing, astronomy all these and other uses that cant now be imagined could be tapped given the space elevator, he said.
The 86-year-old Clarke recounted an earlier prediction about when the space elevator might be up and operating. "Itll be built 10 years after everybody stops laughing and I think they have stopped laughing," he said.
Space debris worries
However, Clarke also pointed to difficulties ahead. "I dont quite know how were going to solve the issue of space debris. Thats going to be a major problem in making the space elevator practical," he advised.
With so much orbiting clutter, including spent rocket stages, dead or dying satellites, zipping around Earth all the way up to stationary orbit, damage to the space elevator is a worry, Clarke said.
There is also concern, Clarke added, that the heavenly elevator is sure to become a target for terrorism. "We need to remove economic and other grudges. But, of course, you could never cope with total lunatics that could do anything."
Although he advocates keeping the lawyers out of space, part of making the elevator reality is hammering out international agreements to utilize the facility for the benefit of all, Clarke said, "and the sooner the better."
"We can solve these problems. We just have to be careful," Clarke concluded.
Lab looks
The magic substance that appears likely to literally hold the space elevator concept together is the carbon nanotube.
A ribbon 62,000 miles (100,000 kilometers) long made of carbon nanotubes would be some three feet (less than a meter) wide and thinner than a newspaper page. But that ribbon would be hundreds of times sturdier than steel and one-fifth the weight.
Carbon nanotubes are getting extensive in-the-lab looks. More importantly, predicted ultra-strength properties of the material appear to be coming true.
ISRs Edwards points to new work in China that suggests carbon nanotubes can be fused together, without need of a matrix material. If perfected, he said, single-fiber carbon nanotubes might offer incredible strength - several times stronger than what is required to fabricate space elevator ribbon.
"I dont see where theres going to be an issue getting to a strength that we can use to build the elevator," Edwards said. Additionally, a number of other space applications are starting to jell, he said.
For example, some experts have begun assessing the feasibility of building large space structures out of carbon nanotube composites, Edwards said. Once the structure is made, then the carbon nanotube surface would be coated with a reflective metal -- perfect as a giant, but lightweight, space-rated mirror.
Worldwide research
Nanotube composite work is a worldwide effort, said Rodney Andrews, Associate Director in Carbon Materials at the University of Kentuckys Center for Applied Energy Research in Lexington, Kentucky.
"This research area has started to catch a lot of momentum, not always necessarily for high-strength composites, but also for multi-functional type materials," Andrews told SPACE.com. "Were learning things very rapidly right nowlaying the groundwork for what we will be able to do with these in the future," he said.
Andrews noted that better techniques to look at and evaluate bonding properties of carbon nanotubes are also quickly evolving.
As for utilizing carbon nanotubes for the space elevator, time will tell, Andrews said. Meanwhile, the incremental steps along the way toward that space elevator ribbon goal are sure to prove fruitful, he noted.
"Right now, it is still a very young field. Its exciting to watch. To date it is too early to say, yes, its going to work [for the space elevator] but it is also too early to say no, its not," Andrews said.
Move the agenda forward
Next year may well be a turning point in the history of the space elevator.
U.S. lawmakers have written into an appropriations bill $2.5 million in funds to foot-the-bill for further engineering reviews, develop data bases, and address critical issues related to the space elevator.
NASAs Marshall Space Flight Center in Huntsville, Alabama and the Institute for Scientific Research see cooperative steps that can put more talent and time on the space elevator effort.
Kevin Niewoehner, ISR President and CEO, okayed use of limited internal money within his organization to push ahead on several space elevator tasks. But much work remains ahead, he said.
"There are political, legal, and environmental issues, as well as technical challenges with the space elevator," Niewoehner said. In his view, NASA and the U.S. Department of Defense (news - web sites) are the two key groups within the federal government most likely to have a vested interest in the project, having the resources, wherewithal, and experience to bring the space elevator into reality.
"We want to drive the message home in Washington, D.C.," Niewoehner said. "This is something that needs to be treated seriously. Its not the lunatic fringe. Its not science fiction. We need to move the agenda forward," he said.
The whole idea works because the top of the system is rotating with the earth, just like a bucket on a rope. You need to do it at the equator, because that's the only place you can spin with the earth without wrapping the tether around the ground.
Hmmmm. Somehow I doubt that.
I did too. I thought the cable would thrash around and be unusable, but it seems the trajectory is stable and smooth. Shouldn't be a problem.
(It's probably obvious that I've never really studied the space elevator concept in any detail.)
Exactly? +/- 50 miles?
There's an island in FSM about 50 miles north of 0o that is stable enough, politically. Its about 1200 miles SE of Guam.
Also, there Jarvis Island, 23' south of the equator. Not too far from American Samoa. Its been abandoned since 1957, and is 100% US property.
Hmmm . . . I was almost positive I remembered listening to NASA types talk about it at the time. Perhaps it was during the earlier experiment in '92?
I remember because I thought at the time that there were no forces acting on it except gravity, and gravity shouldn't make the end of the cable whip about. Of course, "whip about" and "gyrate" are relative terms; any unexpected movement of the end of the cable is going to cause NASA engineers to get excited.
It doesn't have to be anywhere near the equator. Anchor it in Nebraska if you want.
The problem is that the cable would have to follow a the classic "Figure-8" motion characteristic of a non-equatorial geosynch orbit. The higher the latitude, the bigger the motion.
A moving tether means you're gonna have to drag that cable through miles and miles of atmosphere. That creates drag, of course, and it would be necessary to constantly add energy to the tether to keep it orbital.
You'd also have to figure out a way to let the cable move on its anchor.
Two things.
First, the cable won't move. It will be stable.
Second, even if it did move, it wouldn't move enough or fast enough to generate significant atmospheric drag. The atmosphere is only ten miles deep for practical purposes and the rest of the 22,000 miles to geosynch is atmosphere-free.
Say what? How are you going to get that cable up there in the first place? You're going to have to put something in orbit, is how. When you start dropping the line from that geosynch bird, of course it's gonna move.
Now suppose somehow you figure out how to put that thing directly above the latitude of the anchor point. Elementary orbital mechanics says that you're still in an orbit -- how're you gonna keep it from orbiting?
Second, even if it did move, it wouldn't move enough or fast enough to generate significant atmospheric drag. The atmosphere is only ten miles deep for practical purposes and the rest of the 22,000 miles to geosynch is atmosphere-free.
This thing is three feet wide -- try running along holding up a regular newspaper sheet, and you'll understand how much drag a 10-mile long sheet of cable can generate.
And actually, considering the frontal area this thing will present, the drag altitude will be significant well above 10 miles.
For purposes of orbital mechanics, that 10 miles of atmosphere will be plenty -- you're dragging this thing around through the air (probably causing it to twist and flutter, btw), and the drag will need to be made up somehow.
Much easier to just put it at the equator, where the only air you have to move through is the normal old wind.
Of course you wouldn't do that. The point where the cable crosses geosynch will be fairly close to the equatorial plane, just a little to the same side as the anchor point.
It looks like you're telling me that it'll be very near the equator, if not exactly there. If not, I have no idea what you said.
I love it.
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