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Space Elevator Challenge
MattSparkes writes "For the second year in a row, no team has won the $200,000 prize in the Space Elevator Challenge at the Wirefly X Prize Cup. Three teams were disqualified before the contest even started. Another competition at the event has been held up by confusion. Incredibly, it seems the organisers of the competition are not sure whether the ribbon used was 50 or 60 metres long, and whether any team completed the climb fast enough to win."
Maybe so, but I don't see anything here which will realistically form a part of a real space elevator system. Its a bit like building a railroad but starting out with model trains.
http://michaelsmith.id.au
The structure of the elevator isn't the only technology that has to be developed. We also have to make a climber that can go up a thin strand of material and hold wait, as well as a way to power it. Not all of these require carbon nanotube robes to build.
Does a line appended to your comment give your post meaning in and of itself, or only in relation to those without?
I think that the material to make the ribbon can't actually be produced yet, and a 50-60 metre long section is about all that can be used. However, for the purposes of a test like this, it will suffice. The competition is more to do with getting the elevator technology advancing than actually putting together a working device.
Matthew Sparkes
RTFA. You do not need to climb to orbit to win the prize. "a test of over 20 teams to use light to power a vehicle along a tether, this year up about 50 meters..."
SHE does throw dice.
The competition was for building a vehicle to climb the ribbon, not making the ribbon itself.
There is a seperate competition for designing/making the actual ribbon.
Ref: http://www.elevator2010.org/site/competition.html
=Smidge=
is already responsible for a major advancement: the first private space ship able to relaunch in two weeks (SpaceShipOne).
The prize is definately motivation, and the X-Prize foundation has a few contests going:
-The Ansari X-Prize (Get 3 people to 100km twice in two weeks) - WON
-The Archon X-Prize (Sequence 100 people in 10 days with $10,000 cost per person) - OPEN
-The Automotive X-Prize (Currently being developed. Create super-efficent cars or alternative energy) - FUTURE
Those are the three the X-Prize Foundation has created. An interesting fact from the X-Prize website: "Ten times the amount of the prize purse was spent by the competitors trying to win the prize."
"Dictator Flakes. They WILL be delicious."
Infosec: "We don't really know what you're doing, but we're certain it's bad. Disqualified!"
Development: "We're not sure how long the cable is supposed to be, so we'll hardcode it in the top of the code. If we're wrong, its out of scope and we won't fix it."
Engineering: "We don't know how fast it is supposed to climb, so we'll pick a value. If we're wrong, it was Marketing's failure to gather the right requirements.""
Audit: "All your project are belong to us".
Milton: "I could just burn down the building..."
Geez, who is running this thing, the PHB?
I want to delete my account but Slashdot doesn't allow it.
If you attach a weight to a rope and spin it around your head the inertia of the weight will keep the rope tight. Because the Earth rotates, a large mass a long way out in space should be able to keep a line tight. The bottom end would be attached to the Earth, preferabley close to the equator. A station close to Geosynchronous orbit will be in microgravity. The weight at the end of the cable will experience rotational pseudo gravity. Objects dropped from this point will enter solar orbit.
http://michaelsmith.id.au
If I'm going up in to space on a giant elevator, I want it to be nailed on to something a bit more substantial sounding that a 'ribbon'. Heck, all the ones I used to read about in 1950's sci-fi books were basically normal elevators, steel girders, nice big box with windows, sliding doors etc., just a hundred thousand feet high. THAT's what I'd feel safe in.
I want a list of atrocities done in your name - Recoil
And not ONE picture or movie about it? How come?
According to the rules, the circumference of the loop must measure at least 2 metres. ...the Snowstar team from Canada's University of British Columbia, for example, was shy of this by less than half a millimetre.
The diameter of their spool was 0.25% smaller than required, which was probably the result of warping from moving the spool around so it could be weighed, etc, before the competition. So they were disqualified and didn't get to formally compete.
The height of the robot climb is what got me. It's a timed event, and the height they had to climb might have been 10 meters further than the benchmark. Now that's a complete joke.
Dan East
Better known as 318230.
You know how people sometimes use the metric of "If you stacked all the X in the world (graham crackers, AOL CD's, empty pantyhose containers) end to end, it would reach the moon and back!" My tentative plan is to find those items and to dedicate them to that exact purpose. Mole of Twinkies stacked end to end, here I come!
You start at geosynchronous orbit over the equator. You spin your cable both down towards earth and up into space at the same time, which balances the cable.
I've been in the research & development business for pretty much my entire adult life. This, more or less, is what we do except on a different scale. I don't see anything wrong with building models of things in order to understand them more fully. Rather than attempting to solve the whole of the problem in one go they are trying to solve the parts of the problem that are solvable with today's material technology. Given a few more years doubtless the material engineering will begin to catch up and you will see things that realistically could be used in true space elevators.
Nothing in the world is more dangerous than sincere ignorance and conscientious stupidity.
Actually, they did, but in classic NASA fashion, they couldn't remember if they did it in metric or not.
Can anyone enlighten me how that thing supposed to work?
See Wikipedia.
We fasten one end on ground and second end is fastened... where???
To an orbiting counterweight.
And what about Earth rotation?
Earth's rotation is what makes it work. Otherwise:
I still think that normal elevator - a-la tower - is much saner idea and can be achieved easier
Yeah, nobody ever thought of that idea. They're pursuing orbital tethers because they're all insane masochists.
A tower would be much more massive and would have to support its full weight. Tethering to an orbiting counterweight allows centrifugal effects to lighten the total load, since the Earth is rotating. You couldn't build one high enough to reach geosynchronous orbit, and thus whatever you brought to the top wouldn't be in a nice circular orbit when it got there; it would still need something like rocket thrust. With a tether, as soon as you get up to geosynchronous, you're automatically in a circular orbit. See the "compressive structure" entry on Wikipedia.
For those who don't have a good understanding of Space Elevators other than some Sci-Fi you may have read that was written 50 years ago: A space elevator consists of 5 primary components: 1. Base Station 2. Ribbon 3. Climber 4. Counterweight 5. Power system This contest is an attempt to trigger innovation in the area of power and climber, not in the ribbon, station or counter-weight. The ribbon would need to be a carbon nanotube-based composite that is a matter of microns thick and very wide. The width of the ribbon would change based on whether it is in Earth's atmosphere (very thin - less affected by wind and less of a danger) or outer space (very thick, to be able to recover from damage from debris). The ribbon would stretch from a base station to approximately 125,000 km to geosynchronous earth orbit, at which point there will be a counterweight - initially the spacecraft used to deploy the ribbon and eventually an orbital station. The climber drives up the ribbon with an electric engine, and will need to be powered wirelessly. Currently the predominate thinking is to use a laser to hit solar-panels on the climber that are tuned for the particular wavelength of light that the laser is emitting. Initial Space Elevators, built in about 10 years for about $10 B, will be able to carry 20 tons of material at a cost of ~$300/kg (contrast that with the next-gen shuttle - $100 Billion, with a capacity of 40 tons @ ~$10,000/kg), with subsequent elevators able to carry up to 200 tons at a cost of $100/kg.
The problem is the music. We can all stand elevator music for a few seconds, maybe a minute or two. But could you imagine dealing with it for hours? We'd all go stark raving mad!
Small potatoes make the steak look bigger.
Just curious why it is taking so long to measure the the ribbon to see if it was 60 meters or 50? Is there a specific process to it?
Can I bum a sig?
This prize addressed the climber, not the cable, so it's not entirely silly.
What I'd like to see addressed is the fundamental structural problem of stabilizing a space elevator. In getting a payload to geostationary orbit, only about half the energy required is needed for lifting. A similar amount of energy is required to accelerate the payload laterally by roughly 9000 km/h, giving it enough angular momentum to achieve a stable orbit.
A space elevator can lift a payload easily (given some advancement in materials technology), but has no real prospect of pushing sideways on a payload. As a result, conservation of angular momentum will cause the far end of the pendulum to swing. The counterweight tethered past geostationary will swing backwards in orbit, then swing forwards again as a pendulum.
The this very long pendulum will oscillate, not simply be pulled from orbit, and the amplitude won't be that high on the first payload, but every payload lifted will add energy to this pendulum - effectively all of the energy needed to accelerate the payload by 9000 kh/m. That will add up fast, and the space elevator doesn't have much prospect for damping the pendulum. The friction in the cable as it bends will shed some energy, but that's about it. It's like a car with good springs, but no shocks - it's going to bottom out eventually.
The period of a 40000 km pendulum is less than 4 hours, far shorter than the likely time for lifting the payload, so the energy of oscillation will be added somewhat chaotically as the payload ascends. It's not like to can just send of a second payload to "cancel out" the consequences of the first. You really need a strong mechanism that stops the pendulum from swinging.
Socialism: a lie told by totalitarians and believed by fools.
Why this fixation on electric motors for the climber? The travel takes way too long this way. Use rocket engines, I say. Fast, solid, space-proven technology. Plus, you might be able to avoid the tether construction entirely!
Nuffsaid
________
Don't know about his cat, but Schroedinger is definitely dead.
So you are saying that tether might be possible to be made so light and strong - but no way simple tower construct would achieve the same??
Yes. The tether is kept under tension, rather than compression. Different material properties in question. As I said, a tether with an orbiting counterweight has to support less of its own weight than a compressional tower does, due to the centrifugal force.
While a material with appropriate tensional properties for a tether is hard to achieve, a material with appropriate compressional properties for a tower is even harder to achieve.
But how heavy it would have to have?
That depends on the design. Some designs have counterweights on the order of 100-1000 tons.
I shiver to even think that thing might alter (or even de-orbit) Earth.
It's in high orbit (above geosynchronous). It can't just "deorbit" and fall on us; there isn't any atmospheric friction to speak of. It would require enormous energy to alter its orbit to intersect the Earth. You might as well worry about the Moon falling on us.
It kind'a reminds me of other problem, since again we forget about balance.
What the hell are you talking about?
In theory, that's true. In practice, however, science fiction has been a pretty good predictor of technology to come. It's not 100% (yet), but quite often, the 'super high tech' stuff of sci-fi is developed a few hundred years *before* the sci-fi predicted it would be. As for most of the rest? Well, we're running a bit late on actually *using* flying cars, but the technology for them exists.
Tower doesn't have to be all that tall. It must be high enough to fraction Earth gravity force by e.g. ten - requiring ten times less of fuel to launch elevated rocket.
Reducing the force of Earth's gravity by 10 doesn't equate to 10x less fuel. The fuel required is a function of the change in velocity needed; it's more related to reducing energy than reducing force (1/r vs. 1/r^2). See the rocket equation.
Anyway, the altitude required to reduce the force of Earth's gravity by 10 would be almost 14,000 km above the Earth. And you still wouldn't have the right velocity for orbital insertion.
With "space elevator" - no such gradual progress seems to be possible.
Orbital tethers don't have to be geosynchronous. See tether propulsion. Besides, if you crunch the numbers, you will find that a compression tower has to be quite high before any substantial benefit in fuel reduction is achieved.
The cable will probably not oscillate at all (almost) because the cars will ascend at approximatively 100 km/h, by far too slow to do anything except a very small (less than 1 degree) lean at the very bottom of the cable (remember that a lot of payloads will probably be release before reaching 10% of the total cable length).
More details on Wikipedia and googling for "Annual Space Elevator Conference" (there are several simulation for the dynamic behavior of this thing).
There's a hidden treasure in Python 3.x: __prepare__()
You too can try the experiment!
Step 1: you need a long pendulum with a heavy bob, hanging a string from the suspended ceiling at work is a good plan, and you stapler is about the right weight.
Step 2: you need another heavy weight about 2 feet up from the first to simulate the wieght of the station. Borrow your neighbor's stapler too.
Step 3: get the pendulum swinging at least a yard in either direction. Now try to stop it from swinging, but you're only allowed to push on the middle of the string, and you have to push in the same direction for several back-and-forth cycles of the pendulum.
Step 4: OK, that was a bad place for your monitor, pick it up off the floor and put it on a different spot on your desk. It probably still works.
Step 5: explain to your boss the redeeming scientific value of this important experiment!
If we ever want to build an elevator on Mars, we'll just have to grab Phobos and use it as the counterweight, because sadly the elevator will be swinging in the wrong plane to dodge Phobos.
Socialism: a lie told by totalitarians and believed by fools.
If you can make tether that strong and light, you can use N of them to make tower stand. Materials for such tower also can be very very light and very very hard. But probably to not such greater extent tether has to be strong.
What makes super-super-strong tether in your mind possible and super-hard and super-light tower impossible?
Well, for one thing, tensile strength and compressive strength aren't the same thing. A substance which would withstand the pulling force of a fixed space elevator (from earth's surface through GSO to a counterweight) would not necessarily be able to withstand the compressive force of supporting its own weight.
Then there's the balance issue. If you build a tether with its center of mass at GSO, it's in free orbit around the planet. This means it has zero chance of falling over, whereas a shorter tower's center of mass would need to always be over its surface footprint. The higher you make the tower, obviously, the harder this is to maintain.
If you can make tether that strong and light, you can use N of them to make tower stand. Materials for such tower also can be very very light and very very hard. But probably to not such greater extent tether has to be strong.
This is simply untrue. If I'm standing on top of a building and lower a rope to the ground, someone can climb it. This doesn't mean you can build a tower of that height out of the same material (a rope). (In this analogy, the top of the building is the counterweight on the end of the tether, which holds it taut)
But how heavy it would have to have? I shiver to even think that thing might alter (or even de-orbit) Earth. The wikipedia page doesn't answer that question.
It doesn't answer this question for the same reason it doesn't answer the question of whether the Klingons will think that the tether is a threat to them, and therefore attack the human race: it's a complete non-issue. For one thing, the earth gets heavier every day, as crap from space falls into it (from dust all the way up to visible meteors), probably more in a year than the mass of the asteroid counterweight. I'm not worried about de-orbiting the planet anytime soon, are you?
If you're really worried about it, let's make the counterweight out of material taken from the planet, thereby not changing the planet's mass at all, and therefore not affecting its orbit around the sun.
I don't think you grasp how much mass and velocity the planet has.
Reality has a conservative bias: it conserves mass, energy, momentum...
Those are loose nanotubes. I have another experiment for you: Get a 3" square of some copper screen, made with a fairly small wire. Try to melt the center of it with a lighter; experience defeat. Now pull one wire out of the mesh, and try to melt it with a lighter. You will succeed. In that moment, the student will be enlightened.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
The presence of a 1000-ton mass beyond geosynchronous orbit will have an utterly, utterly negligible effect on the Earth's center of gravity or on tidal forces.
Take tidal forces, for instance. The distance geosynch orbit is about 40,000 km (I'm rounding up to 1 sig fig); the radius of the Moon's orbit is about 400,000 km. Since the counterweight is 10x closer to the Earth than to the Moon, that increases its tidal strength by the cube root of 10, or about a factor of 2. However, that is offset by a 10^20 reduction in mass. So the tidal forces due to the counterweight would be almost a billion trillion times weaker than those of the Moon.
The counterweight used in many space elevator designs is not that much more massive than the International Space Station. That certainly doesn't produce significant gravitational effects, despite being in low Earth orbit instead of geosynch. Hell, even a typical-size asteroid in low Earth orbit wouldn't produce significant gravitational effects at the Earth's surface.
Once the payload is released from the cable, it will need additional thrusters to move it away from the elavator, adjust it's orbital height, orbital plane, and LAN.
Today's fun fact: a mole of Twinkies stacked end to end, assuming they're about three inches long (I haven't one around to measure), would stretch from here to Andromeda and about 90% of the way back.
I was one of the team leaders for one of the elevator games teams. The article linked here gives some sense of the incompetence of the competition organizers, but the truth of the matter was far worse. The climber challenge was fraught with late/nonexistent equipment, no parity in the rules between the teams, vague rules and inaccuracies along every step of the way. The tether strength challenge was a joke, with professional organizers funded by NASA failing to properly carry out a test that any science/engineering student could do in first year.
To give an analogy, dozens of teams put thousands of dollars and hours into building race cars, only to show up at the venue and find that instead of a formula one circuit there was a dirt track through a cornfield. Our team spent thousands of hours on our entry and so did all of the other participants. It's too bad the organizers couldn't have repaid this dedication and passion with a small amount of their own effort.
First, there actually *is* friction. So it's obvious the elevator would not swing forever. Second, you claimed that each cargo sent up would tend to strengthen the swinging, until something breaks. That's also not true. That *would* be true if the cargo was sent up and released at the worst possible moment.
In the best case, two following cargoes cancel exactly. Like this:
First cargo goes up, presses top eastwards, whereafter the top swings westwards to neutral, and *would* overshoot to go an (almost) equal distance westward. Except you send up cargo 2 with such timing that it's eastward pressure cancels the westwards motion of the elevator, so that at the moment you release cargo 2, the elevator is both vertical, and at rest.
In practice, there's likely to be many cargoes on the way up at any given time, this acts a lot more like a *constant* eastwards pressure. (in the limit, infinitely many infinitely small cargoes, it *would* be a constant pressure)
You *do* need to take care that you don't put energy *into* the standing waves that will inevitably build quicker than the energy dissipates. That can be taken care of in two ways (or a combination thereof).
Put less energy in. (by timing, by size of cargo, by equal-symetrical-shipping whatever)
Or make the energy dissipate faster, by passive means (increase friction, dampeners) or active means (ion-trusters at top , or movement of the bottom-point that actively work against the waves, for example)