If the math is right, then the biggest portion must be in the outer atmosphere...then Lucas was right...
Posted on 02/15/2006 10:24:11 AM PST by Neville72
In January, LiftPort team members deployed a mile-long tether with the help of three large balloons in the Arizona desert (N Aung/LiftPort Group)Related Articles A slim cable for a space elevator has been built stretching a mile into the sky, enabling robots to scrabble some way up and down the line.
LiftPort Group, a private US company on a quest to build a space elevator by April 2018, stretched the strong carbon ribbon 1 mile (1.6 km) into the sky from the Arizona desert outside Phoenix in January tests, it announced on Monday.
The company's lofty objective will sound familiar to followers of NASA's Centennial Challenges programme. The desired outcome is a 62,000-mile (99,779 km) tether that robotic lifters – powered by laser beams from Earth – can climb, ferrying cargo, satellites and eventually people into space.
The recent test followed a September 2005 demonstration in which LiftPort's robots climbed 300 metres of ribbon tethered to the Earth and pulled taut by a large balloon. This time around, the company tested an improved cable pulled aloft by three balloons.
Rock solid To make the cable, researchers sandwiched three carbon-fibre composite strings between four sheets of fibreglass tape, creating a mile-long cable about 5 centimetres wide and no thicker than about six sheets of paper.
"For this one, the real critical test was making a string strong enough," says Michael Laine, president of LiftPort. "We made a cable that was stationed by the balloons at a mile high for 6 hours…it was rock solid."
A platform linking the balloons and the tether was successfully launched and held in place during the test. LiftPort calls the platform HALE, High Altitude Long Endurance, and plans to market it for aerial observation and communication purposes.
But the test was not completely without problems.
The company's battery-operated robotic lifters were designed to climb up and down the entire length of the ribbon but only made it about 460 m above ground. Laine told New Scientist that the robots had worked properly during preparatory tests and his team is still analysing the problem.
Carbon nanotubes In March, LiftPort hopes to set up a HALE system in Utah's Mars Desert Research Station and maintain it for three weeks. Then, later in the spring, Laine says he wants to test a 2-mile (3.2-km) tether with robots scaling to at least half way up.
Laine aims to produce a functioning space elevator by 2018 – a date his company chose in 2003 based on a NASA Institute for Advanced Concepts study, which said an elevator could be built in 15 years. "This is a baby step, but it's part of the process," he says of LiftPort's recent test.
The idea is to build the actual elevator's ribbon from ultra-strong carbon nanotube composites and to have solar-powered lifters carry 100 tonnes of cargo into space once a week, 50 times a year.
Beams and climbers Laine sits on the board of the California-based Spaceward Foundation, which partnered with NASA to put on two space-elevator-related competitions that were the first of the agency's Centennial Challenges programme – the Tether Challenge and the Beam Power Challenge.
The first is designed to test the strength of lightweight tethers while the beam challenge tests the climbing ability and weight-bearing capability of robots scaling a cable. Laine’s team is not competing in the NASA challenges so there is no conflict of interest.
In October 2005, none of the competition entrants performed well enough to claim the twin $50,000 purses. But the challenges are scheduled to take place again in August 2006 with $150,000 top prizes. Nineteen teams have signed up for the beam power challenge so far and three will compete in the tether challenge.
Ben Shelef, founder of the Spaceward Foundation, hopes the competitions will drum up interest and drive technological innovation. He told New Scientist he is pleased to hear of LiftPort's successful test. "A journey of a thousand miles starts with a single step," he says.
This topic has been discussed at length here on FR for many years. The characteristics of the space elevator are already well known.
At some point in the trip, wouldn't centrifical force take over? You wouldn't need independent power at some point.
Isn't the Moon at 62,000 miles? I could be wrong. I am too lazy to look it up.
The test was of a cable a mile long. This is a length easily achievable by many kinds of filaments besides nanotubes.
Another question. Won't a certain weight that far out cause the earth to shift off its rotation because of the weight of the other side pulling it? I know moving half the earth would be hard, but would it require that much to have an effect?
There is a reason that it is called geosynchronous orbit.
It would alter the centre of mass of the earth, relative to its axis of rotation, but only by a relatively infitesimal amount. The earth weighs 6.0 * 10^24 Kg (six sextillion metric tonnes) - the mass of any proposed space elevator would be miniscule by comparison.
"What floor, sir?"
"Penthouse, please"
The horizontal force you're talking about will come from the ribbon itself, resulting in the ribbon being bent into a "C" shape as the payload rises.
Yes, and that force will result in the ribbon coming to the ground at a greater angle (wind resistance will mean it won't be perfectly vertical even when not being climbed), producing additional horizontal force components at its mooring, which will opposite in direction to the earth's rotation, bleeding off a little of its angular momentum. There's no free lunch, and since the elevator system itself, once in place and stable, has no source of additional energy (like thrusters on the station or counterweight), it must come from the earth itself.
Now you get the jest of my arguement... Thank you...
It isn't geosynch if it is attached to earth...
I get the gist of your argument, at least as it applies to sattelites. In the case of a space elevator, however, there IS a source of energy available - the angular momentum of the earth's rotation, transferred through the cable attached to the earth.
It's the compounded weight that would be effected by gravity and the counter weight that cannot change mass once in orbit, to handle even a miniscule payload would disrupt the balance and come down by the weight of the cabling, and payload. The stress on the structure itself would be immence. ever been on a suspended bridge in high winds?
the angular momentum wouldn't be making this a vertical trip and eventually, the rotation would cause the whole thing to wrap around the earth... Again, theory and fantasy, not practical or possible. Ever seen a spinning galaxy, think of the arms.... this would be the effect.
Horizontal AND vertical forces at its mooring AND at the point 62,000 miles out, lowering the orbit of the endpoint and shifting its location. You could end up "cracking the whip" with that endpoint. If there's a mass out there to provide tension on the ribbon, you could lose it.
Guys, check out this link:
http://www.zadar.net/space-elevator/
and I think all these questions will be answered, assuming you can understand it all. I admit some of it flew over my head, although with some study I could probably understand it all. All the objections you raise to the theoretical possibility of a space elevator have been considered. Cracking the whip or wrapping the whole thing around the earth is not a concern. Many, many practical difficulties do exist, however.
Do you want to give this a try? Your ability to explain technical matters is exemplary, and may possibly be up to the task of bring Zavien up to speed. I suppose I could try, but I'm not as proficient as you seem to be.
Was not intended for you. It was meant for Ichneumon
Copy and paste error.
Ichneumon,
do you want to try?
LOL!
Can I buy shares yet?
If the math is right, then the biggest portion must be in the outer atmosphere...then Lucas was right...
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