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Skyhook Robot Passes 1000 Foot Mark
JhohannaVH writes "MSNBC.com is running a story about yesterday's successful test of the Space Elevator!! Maybe it will become a reality after all." From the article: "This week's testing involved a 12-foot (4-meter) diameter balloon. Safety lines held by team members kept the balloon from floating away. The ribbon dangling from the balloon was made of composite fiberglass, with the robot lifter running up and down the tether ... During the day, the highest altitude reached by the balloon/ribbon/robot combination was 1,000 feet (305 meters). 'It gives us complete confidence that the mile goal is well within reach,' Laine said. Laine said that the Federal Aviation Administration has been very supportive and helpful in orchestrating their test flights. "
117,407,136 to go
1000 feet? Nice, a "space elevator" (circa 2005) almost two-thirds the way to the top of the Sears Tower (circa 1973).
This makes my launch of my Estes Andromeda a successful test of intergalactic travel.
If my elivator is in flight I think i'd decide that would be a good time to choose a religion.
Live according to the Categorical Imperative. If the Categorical Imperative tells you not to live by it... ignore it
Centripetal acceleration
It's kinda annoying to see every space elevator article attract a swag of ill-informed comments that get modded as insightful. Please go read question 4 of the FAQ.
the ribbon recovers for the same reason that it stays up in the first place. Centripetal acceleration is acting on the counterweight pulling it outward, and the lost angular momentum is replaced very quickly (essentially as fast as it is lost). The ribbon will never lose enough angular momentum to even deflect a single degree, let alone fall. The extra angular momentum is stolen from the Earth's rotation; we will have to worry about this effect slowing down the Earth and making the day longer if we ever decide to ship Australia into space.
How we know is more important than what we know.
sp. Centrip/e/tal. And technically, it keeps it down.
Thrusting from the bottom is expensive. It requires extra weight to be carried as fuel (or a Big Friggin' Laser). You could instead adjust the counterweight position at the top so that it begins to move away from the Earth by itself. There is some fine-balancing involved, naturally.
"To an extent, Mr. Swartz is correct: As payloads are moved up and down the elevator, the ribbon is distorted, and it would move the counterweight. Nevertheless, looking at the travel time and the relative masses of the climbers, the ribbon, and the counterweight, we find that the distortion is extremely small and would be quickly corrected because of the forces that are felt by the ribbon and the counterweight. The rotating Earth supplies the needed angular momentum through the anchor and the ribbon. The rotation also provides all the restoring forces required--no rockets are needed to move the counterweight. The best way to look at this may be to think of the space elevator as a pendulum. If you pull the ribbon from its normal position--rising straight up from Earth--the forces will always pull it back."
--Brad Edwards
A fifth of a mile may be a tiny fraction of the distance needed to climb a real space elevator, but that's almost beside the point. If this doohickey can climb 1000 feet it can climb a hundred million, assuming the battery holds out. It just has to keep trundling upward.
The cable is the scientifically hard part, not the climber.
I have been following the progress of research concerning space-elevator for some time now. The LiftPort Group of companies working towards a space-elevator are making a great deal of progress. See here and here for more LiftPort specific information. Slashdot reported on the faa approval of their high altitude tests several days ago -- refer to that thread for some interesting discussion. Check here and here here for several reports concerning the viability of the elevator -- be sure to check the NIAC pdf. Also, Blaise Gassend has a great collection of information. Finally, though carbon nanotubes are still in their infancy (its been a little over 12 years since they were discovered) - their theoretical tensile strengths are perfect for use in the construction of a space elevator tether. This recent development spells a rosy future, and many innovations yet to come.
...Stairway To Heaven was looping on the Muzak. Frickin' annoying!
"This visionary concept would make use of an ultra-strong carbon nanotube composite ribbon stretching up to 62,000 miles (100,000 kilometers) from Earth into space." 62,000 miles?!?
This thing is of course, pretty cool, but it seems to me to be a pretty basic mechanical device. My understanding is that developing ultra-high tension/flexibility nanofibers capable of stretching from Earth to orbit, and developing the orbital platform was what made construction of a space elevator difficult.
My two cents.
_________
As Diddy says: Don't pull out your wallet if you ain't going to use it.
------ The best brain training is now totally free : )
Nice, only of course this 'test' misses the one crucial, difficult part; the material to make the wire from. The space elevator will be built (either in tether form or in straight up crawl-up-the-nanotube form)...as soon as we can create the lenght of the material needed. That is the only technology needed to be tested; the rest (ie what they tested here) is a relative no-brainer on which funds needn't really have been spent. Proof of that; I doubt they learned anything crucial (or even really relevant) which can be applied to the real, fuill scale thing.
-- Waht? Tehr's a preveiw buottn?
I mean, it's all very well and good that CNT's may be able to THEORETICALLY provide the strength necessary for the cable, but you know there's always this annoying discrepancy between theory and practice. Afaik, they still haven't achieved the necessary strengths in lab tests.
File under 'M' for 'Manic ranting'
"This lifter is much smarter than our previous versions. It's our 18th version..."
...
...?
Version 1 Logic: Go up.
Version 18 Logic: Go up.
aoeu
The climber is trivial, compared to the cable. Wake me up when they have a cable that can hold 100 GPa and is longer than a millimeter.
Human genome = 3 billion base pairs = 6 GBit. Windows + Office = 20 Gbit. Which is more impressive?
I've been editing the video from the 1,000-foot robot test. Since I've been busy lately with grant writing etc., I wasn't involved in activities like making the ribbon. So it wasn't until I was watching the video that I noticed the sentence written in block letters on the 2-inch wide ribbon (which alternates color in 50-foot strips of bright yellow and fluorescent orange) near the top:
ATTENTION PILOT: IF YOU CAN READ THIS, YOU'RE TOTALLY SCREWED.
Our sense of humor (or at least Nyein's) may not (or it may) be visible from far away, but it's there.
Comment forecast: Bits of genius surrounded by a sea of mediocrity.
s/successful test of a space elevator/successful test of a balloon/g
Gigabytes have been written on the subject. Look it up yourself.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
As I understand it, most of the fuel that you expend in a standard launch is there to make sure that the rest of the fuel can make it high enough to finally push the payload into orbit.
With a space elevator, you're no longer required to accelerate several dozens of tons (>90% of which is just fuel) up to 7 miles/second just to get a 500lb satellite in orbit. The cost savings would be huge.
Now granted, you'll still have to haul some fuel up the elevator, but it's like the difference between climbing the stairs to reach the top of the Empire State Building vs. jumping to the top from street level in one bound.
Give 'em enough rope...
and they'll hang themselves.
"Speaking the Truth in times of universal deceit is a revolutionary act." -- George Orwell
The hard part of the space elevator is NOT the climber
There are a lot of hard parts of the elevator's "baseline design." The climber is one of them. It's not easy to make a robot that can climb 62,000 miles reliably. The first thing you have to do is make a robot that climbs at all. Then you improve its reliability a whole, whole lot - by having the robot climb a whole, whole lot, find out what fails, and improve that piece.
Besides the cable, and the robot, you also have to worry about power delivery, deployment, ribbon design (not strength). Each of those is not an easy problem. You do need to solve all of them.
Of course it's a PR event. Guess what? Our lack of a space elevator is a PR failure. You seriously think that with one or two hundred billion $ (i.e .5 fewer oil wars) we couldn't overcome every lingering engineering hurdle and build one of these things? So many of today's problems are described as scientifically insurmountable when really, it's just a question of misplaced priorities. With a really large (but not infeasible) amount of money we could cure cancer and AIDS, blanket Africa with enough doctors and teachers to spark a humanitarian revolution, and have prolly enough left over to get fusion/microwave power off the ground. Take your pick. The American voters have, and that's why things are the way they are. Launching a public awareness campaign for whatever your pet cause is looks like a smart move to me.
I think there is a world market for maybe five personal web logs.
The other day, while at a bar, I told people that I can jump over the moon.
I'm proud to announce that today I jumped 2 feet- a critical proof-of-concept that demonstrates the feasibility of my claim. Maybe I'll be able to back it up after all!
The plane does, while strumming the lowest note ever played in human history in the process.
-PS
"All that is necessary for evil to succeed is for good men to do nothing." - Edmund Burke
If you want to be rational about space elevators you have to face the fact that nanotube ribbons don't yet exist but ribbons made of materials like Dyneema or Spectra do. So what? Here's what.
Seastead this.
The space shuttle costs 450 million dollars per launch. This would cost much more than that, but the upkeep should cost a small enough amount that it might pay off in the long run (Depending upon it's projected lifespan).
In an article by Bradley Carl Edwards in the August 2005 print issue of "IEEE Spectrum", he writes "The estimated operational cost for the first elevator is several hundred dollars per kilogram to any Earth orbit, the moon, or Mars, a drop of two orders of magnitude over the cost of current launch technologies. With the completion of subsequent elevators, the cost would drop even further, to a few dollars per kilogram." So using a space elevator to transport whatever is cheaper than using rockets for transportation.
FalconShould there be a Law?
Well, launch costs to GEO are $10,000+ per Kg. If you could move up a couple of tons at a time while saving two orders of magnitude on cost, that's economic viability.
> What keeps it up?
Viagra for space elevators.
Join the Slashcott! Feb 10 thru Feb 17!
From my limited understanding, the problem with a space elevator is essentially that the ribbon is kept tight (and under massive strain) due to it's length and the mass located out in space. So why not have a sequence of ballon mounted elevators (ie. one at 1000 feet, another from 1000 to 2000 feet, etc) allowing some slack in the ribbon? Once we get to a point where balloons are no longer feasible we can start using a real space elevator. The final "real space elevator" would no longer extend so far into the Earth's gravity-well and so is more easily built.
Well I live in Australia and I personally like this idea of sending the whole country into space. Sounds like fun. My only question is will my taxes go up to pay for this journey?
The theory seems to be that you start small, and you get progressively bigger and bigger until all of the problems are solved. The first time it may have been a small motor with a battery climbing a 100 foot rope up the side of a building. This time it was an 18th generation lifter with cargo capacity climbing a 1,000 foot high tensile ribbon connected to a balloon. Next time it may be a climbing a 10,000 foot high tensile double ribbon using laser power. Or maybe it will be a 1,000 foot carbon nanotube wire in a year-long stress test, with a climber specifically designed to do maintenence on the tether.
Eventually they'll get there, and this is a definite step in the right direction. While the tether may be the biggest unknown of the project, we still don't have much experience with this sort of thing. What safety systems should be on the lifter? How should it be powered? How long will such a thing last before it breaks down? How long will the tether last? How will the system weather storms? How will it weather space debris? How will you find a patch of ground strong enough to anchor the thing to? How do you keep the climber from jumping the track? How do you keep parts from freezing as it goes from wet tropical climate into space? The theoretical engineering may be done except for the cord, but many, many practical engineering considerations remain.
I applaud this team's efforts, and wish them much luck.
The ______ Agenda
So instead of tethering the cable to a balloon and having it climb a measily thousand feet, why not loop the cable around a couple of pulleys to form a cable treadmill, and let the climber "climb" all the way? Give the climber a real workout. This test smacks more of publicity stunt than of useful research to me.
"I'm not impatient. I just hate waiting." - My Dad
We currently build transoceanic fiber optic cables that can be completely powered from one end using DC power, with the ocean acting as ground (current technologies require a powered repeater every so often), so we have already built power cables within an order of magnitude of the required length (though the energy it would need to carry would likely be much much higher - a single crawler might use several megawatts continuously)
I would be curious to know how a power cable on a space elevator would interact with the Earth's magnetic field. Would it impart a significant force on the cable? Would the cable need to be shielded?
Alternatively, what are the power generation options in space? Could a nuclear powered crawler be built, and/or could power generation facilities be spaced at regular intervals along the cable?
Create a SPACE PULLEY instead of Space Elevator. We can have a pulley hanging form space just above the atmosphere. The pulley hangs from a geo-stationary Space Taxi Station. A small Space Taxi is released up using a very very large helium balloons. A platform can be made that has large number of huge helium balloons below it. The Space Taxi is stationed on this platform before the whole platform is released. When the platform reaches to the limit that it rise up in the atmosphere, Space Taxi takes off form the platform using jets propulsion and quickly reaches to the hook of the Space pulley which is just above the atmosphere and hooks itself to it. After this the Space Taxi station just pulls up the Space Taxi. Note : All this is done with minimum fuel requirements compared to the other technologies, so what say ? Space travel cheaper than land travel say from India to USA ? PS. A compressor can be used to bring the balloon Platform back on earth.
i can understand the lakers might want to build a robot that plays like karim abdul jabar, but 1000ft is over kill.
"Centripetal acceleration" only says it will keep this thing from flying into space, nothing more. Tie a string to a small object and spin it. The centripetal force is the part of the tension in the string pulling the object towards the centre. Centripetal acceleration is the effect of that force that curves the object's trajectory, instead of letting it go in a straight line.
But here's the catch: centripetal force is _strictly_ the component pointing at the centre of the circle. It can't accelerate or decelerate the rotation. The reason you can accelerate that small object on a string is precisely because the string is a little crooked, and it pulls a little forward too, in addition to the centripetal force pointing at the centre.
The apparent force pulling it outward, that they mention there, is called "centrifugal" (runs away from the centre), not "centripetal" (pulls it towards the centre). This one doesn't do anything to keep it from losing angular momentum. Hold your hand still after you've made your object on a string rotate. It's seeming to tug outwards is centrifugal force. Note how the item can slow down due to friction anyway.
And things get even more screwy in a gravity well.
Basically what I'm trying to say is that while I'm sure some actual physicists did some actual calculations for that project, and they probably have a very sound theory of how it regains lost momentum (and how much can it safely lose or gain before that string breaks), that quoted explanation isn't it. It's some handwaving that's as "scientiffic" or "informative" as saying that Santa's reindeers keep it up.
"It's kinda annoying to see every space elevator article attract a swag of ill-informed comments that get modded as insightful."
I feel your pain. I found it slightly annoying too to see your quote of that pseudo-science babble modded as "+5 Informative". No offense, since you're not the one who wrote that, but it's got exactly zero useful information, and doesn't answer the question at all.
I'd imagine that the reason people keep asking is precisely because that handwaving doesn't answer it.
A polar bear is a cartesian bear after a coordinate transform.
Actually there is a project to use large balloons as heavy slow lifters. 1st stage balloon lifts the orbit balloon which uses an ion engine to get into orbit. It will take weeks to lift anything into space but it would be cheap and repeatable. http://www.msnbc.msn.com/id/5025388/
I would be curious to know how a power cable on a space elevator would interact with the Earth's magnetic field. Would it impart a significant force on the cable? Would the cable need to be shielded?
Indeed there would be interactions, there have even been plans, and some developments, in deploying long conductive wires ('tethers') from the shuttle to study this (and possibly generate energy from the tether crossing mag field lines). Up to now actual tests were not very successful I think (the last tether I heard about, a Nasa/Esa/italian development, catched fire during deployment)
But even more than this, I think adding to the wire the need to feed electrical kilowatts upwards and downwards would mean yet another constraining specification to a system that is already quite intensely constrained by the pure weight issue, and just this may be a show stopper.
I for one would confirm the 'laser feed' choice as the best one, even if this means a bit of pointing / tracking from ground.
Herve S.
But what might really do it in, though, is this ribbon is going to be a giant electrical generator. As it orbits through the earth's magnetic field, it's going to develop a tremendous charge along its length. What will dissipate that charge? Is the fiber going to be adequate to carry that charge? Do we ground the terminus or use the current? And what happens to the fibers as the ribbon expands, contracts and flexes throughout the day? Will microscopic voids appear in the fiber, which may in turn cause tiny arcs? And might these arcs eventually burn through the fibers, causing catastrophic failure?
Incorporating 22,000 miles of 0000 gauge copper welding cable is not likely to be a good answer, at least not from a weight / strength / cost perspective. But something will need to deal with the charge, and I've seen nothing so far that does.
So, throw in several dozen masters' theses worth of materials science, and you want it to magically incinerate as it falls, too? Well, why not?
John