Space Elevator Challenge 162
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."
X-Prize (Score:2)
More and more I see that this sort of prize is excellent way to foster development of new technologies. This should be applied to other technical challenges we face...
Re: (Score:3, Insightful)
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.
Re:X-Prize (Score:5, Insightful)
Re: (Score:2)
Yes but, if you were running a competition, do you think you could remember how long the cable is?
Re: (Score:2)
Re: (Score:2)
no.
Re: (Score:2)
Re: (Score:2)
Besides, an Apollo scaled project is beyond the capability of America.
Re: (Score:2)
It's not a question of "require" it's a question of benefit from.
Lots and lots and lots of engineering-projects would benefit from stronger, ligther cables. Any sort of tension-structure at all really. The most obvious example migth be bridges.
Yes, you can build bruidges with steel-cables. But if you had cables 10 times as strong, and 10% the weigth, you'd be able to build much longer freespan bridges, and you'd be able to sa
Re: (Score:2)
Its a bit like building a railroad but starting out with model trains.
Indeed. It rather reminds me of one of those black and white 1920s films where everyone is running around at high speed, to a catchy little ditty on the piano, only I'd take it less seriously. I mean what, from the sounds of it these guys couldn't find a good time in a whorehouse, and they claim they are trying to build a space elevator?
In the words of the Jesus
Laughable, man! Haaaaa ha!!
Re: (Score:2)
A montage of failed flying machines from the 1920's [google.com]
That flying gimmick will never take off :)
Re: (Score:2)
That flying gimmick will never take off :)
Do you think they managed to remember what the wingspan was, down to the closest 10 meters or so? These guys should have their own sitcom, seriously.
Re:X-Prize (Score:5, Interesting)
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.
Re: (Score:2)
Re: (Score:2)
While this comes from the realm of science fiction (where did I read about this? anybody recognise it?), it's still an interesting idea:
Imagine two e
Re: (Score:2)
No, sorry. It sounds a bit like something Robert Forward would have come up with.
Re:X-Prize (Score:5, Informative)
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 [wikipedia.org] and googling for "Annual Space Elevator Conference" (there are several simulation for the dynamic behavior of this thing).
Re:X-Prize (Score:5, Insightful)
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.
Re: (Score:2)
Re: (Score:2)
Sure, the cargo needs to be accelerated eastwards, which means the top of the cable will be pressed westwards. But the cable is under stress, and the stress itself will tend to rigthen it.
It's a lot like spinning a string with a rock on the end. Sure, gravity will tend to drag the rock *downwards*, but the spin and the resulting stress on the string will tend to counteract this. End-result ? The string does go diagonally downwards somewhat, how much depending on weigth of stone, length of strin
Re: (Score:3, Insightful)
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 we
When physics hands you a lemon, make lemonade. (Score:2)
Seems to me you can turn this to your advantage:
Initially the climber plus payload pulls the counterweight back - but then it swings forward, converting a backward momentum delta to a forward one, which you can then use to accellerate the payload further with more climbing. When you get to a decent release point you can also wait until you've got extra forward momentum to help circularize your orbit or improve your launch, and le
Re: (Score:2)
- you don't need to "circularize" if you get to geosync altitude,
- somewhere below that you can let go and end up with an eliptical orbit with perigee sufficiently above the atmosphere, and
- energetically, if you want to head out it's better to climb PAST geosync and take off than to let go sooner and use some thruster.
But using the momentum from the tether's vibration lets you cut loose lower, reducing the amount of space-elevator time needed to achieve your goals. Spac
Re: (Score:2)
You really need a strong mechanism that stops the pendulum from swinging.
Vary the location of the exit point at the top from payload to payload to keep resonances from building up.
Re: (Score:2)
Re: (Score:2)
The counterweight tethered past geostationary will swing backwards in orbit,
More-or-less correct.
then swing forwards again as a pendulum.
No, it won't. There's no restoring force here anywhere. If you are trying to orbit any kind of "counterweight" past geosync, then the orbital period of that counterweight will be longer than one day and thus it'll start wrapping the entire tether around the planet.
To quote someone's sig around here: None of this is rocket science, really:
Write down the total f
Re: (Score:2)
Nothing bizarre about it. It's called "physics".
I.e. people like yourself.
I gave you all the required pointers. With them, you can go and see for yourself by yourself with your own eyes that a space elevator cannot exist. But
Re: (Score:3, Insightful)
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 h
Re: (Score:2)
Ribbon (Score:5, Insightful)
Re: (Score:2)
But how does this help? $200,000 is chump change. It's not enough to pay the guy who runs the accounts of a serious research project. That number needs another three zeroes on the end before it will actually produce anything new.
As the article says, none of the teams actually created their own materials, they bought off the shelf. That's like trying to push forward hybrid car technology by awarding a prize to the team that brings the cleanest Prius.
Re: (Score:2)
It's not the money that makes them do it. It's the competition. The notion that other people are competing for the same prize awakens something primal in human nature, and drives us to the goal. $200k isn't much money, but it's enough to get the attention of the people competing.
X-Prize Foundation (Score:5, Interesting)
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."
Re:X-Prize Foundation (Score:5, Interesting)
Re: (Score:2)
I'm not knocking the acheivement of this group, just putting it in perspective.
At least they managed to get higher than 50 meters. Or was it 60? Haaaaaaahahaaa, tragic...
Re: (Score:2)
What it is good for though, is setting actual real-world goals for scientists to achieve, learn from, with the prospect of winning the prize and the fame. They compete with other entries and i
Sounds like IT (Score:5, Funny)
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?
Re: (Score:2)
/rimshot
Call me picky but.. (Score:4, Funny)
Re:Call me picky but.. (Score:4, Insightful)
Re: (Score:2)
Re: (Score:2)
Nanotech? (Score:2)
Re: (Score:2)
However, unlike warp drive, it's at least not violating the laws of physics.
Yes, it is very much violating the laws of physics.
Of course I cannot force you to open a mechanics book. That would be up to your motivation.
Re: (Score:2)
Re: (Score:2)
Re:Call me picky but.. (Score:4, Funny)
lots of competitiors, drama, technology. (Score:2, Interesting)
Pretty picky (Score:3, Interesting)
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
Re: (Score:2)
My plan! (Score:4, Funny)
That's a big Twinkie. (Score:2, Funny)
Intro to Space Elevators (Score:2, Informative)
Re: (Score:2)
It takes a ton of energy to climb alot of weight. Going slowly can help cut down air drag, and so can not having to lift the energy source and motor, but anchoring to the rope is probably antithetical to going up fast, and it will need some speed (~180 kmh)
It's the music! (Score:5, Funny)
How long does it take to measure 60 meters? (Score:3, Interesting)
Why electric? (Score:5, Funny)
more brilliant than it may appear (Score:2)
The only benefit of the thether system is that it allows slow speed climbing. For some reason, we don't value trains that go 1 m/s, and if they can't have climbing bots go up and down on the same thether, which would indeed seem like a big complication, and there's no room in space to store a bunch of robots so you ca
Re: (Score:2)
Considering the innefficiency of lasers multiplied by the innefficiency of solar panels, if a thether is useful, then an electrically conductive power transmitting thether is necessary. Powered in part by slowly falling (braking)
100 metre (Score:2)
There would have to be some weight restrictions. Build a tower that tall and see who can
climb up.
a word from a participant (Score:2, Informative)
Re: (Score:2, Insightful)
Re: (Score:3, Informative)
Re:How could you do this now? (Score:5, Informative)
There is a seperate competition for designing/making the actual ribbon.
Ref: http://www.elevator2010.org/site/competition.html [elevator2010.org]
=Smidge=
Re: (Score:2, Insightful)
Re: (Score:2)
Re:How could you do this now? (Score:5, Insightful)
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.
Re:How do they work? (Score:5, Informative)
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.
Re: (Score:2)
Re: (Score:2)
Re: (Score:2)
Re: (Score:2)
1. make two cables one going down, and one going up to counter-ballance. after a while the downward bound cable touches the ground and gets tied off you keep making the downward a bit longer to stand-off the countermass from the geosync point. Then if possible You then add mass to counter-ballance and reel in the counter-mass cable as you go. once the counter-ba
Re: (Score:2)
Re: (Score:2)
Area Ranked 49th
- Total 2,491 sq mi
(6,452 km)
- Width 30 miles (48 km)
- Length 100 miles (161 km)
- % water 21.5
- Latitude 3827'N to 3950'N
- Longitude 752'W to 7547'W
( source: http://en.wikipedia.org/wiki/Delaware [wikipedia.org] )
Re: (Score:2)
Re: (Score:2)
More specifically, at the equator it would be geostationary orbit.
Re: (Score:2)
Re: (Score:2)
The station is in geostationary orbit. The counterweight is beyond geostationary, exerting considerable tension on the cable.
If it is beyond geosync, then its orbital period is larger than one day. The "tension" it will exert on the station is thus not radial away from the earth but towards slowing the station down. Slowed down, the station will fall closer to the earth.
The whole thing will simply wind up around the planet.
And at all of /. there's nobody capable of doing the imple math to recognize t
Re: (Score:2)
It is not in orbit. It is tethered.
Bzzt (Score:2)
Re: (Score:2)
Re: (Score:2)
See http://en.wikipedia.org/wiki/Space_Elevator [wikipedia.org], or for that matter Arthur Clarke's "The Fountains of Paradise".
The clue is that an elevator is attached to a *GEOSYNCHRONOUS* satellite. That is, it will stay at the same place above the Earth's equator. Granted, there would probably be some amount of drift, but that can probably be solved by applying steering thrusters to
Re: (Score:2, Interesting)
Re:Didn't measure the tether first?! (Score:5, Funny)
Re:Other end? (Score:5, Informative)
See Wikipedia [wikipedia.org].
We fasten one end on ground and second end is fastened... where???
To an orbiting counterweight [wikipedia.org].
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 [wikipedia.org] on Wikipedia.
Re: (Score:2)
Precisely my question. 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???
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 tethe
Re: (Score:2)
Do a couple of calculations. The ribbon is a fraction of mm thick and from some mm to maybe one meter wide, and 40,000 km long. Its mass is very small, some thousands of tonnes probably. That's insignificant with respect to Earth's mass.
A tower, on another hand, would be *much* more massive, not to mention impossible to build with any known, or foreseea
Re: (Score:2)
IOW, the tether would manage to: (1) be very light, (2) be strong enough to sustain centrifugal energy of counter weight, (3) be even more stronger to carry useful load.
Just how this more feasible that ribbon is a fraction of mm thick and from some mm to maybe one meter wide would manage that?
Your post suggest that material for tether/ribbon is already known. So why we
Re: (Score:3, Informative)
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 [wikipedia.org].
Anyway, the altitude required to reduce the force of Earth's gravity by 10 would be almost 14,000 km
Re: (Score:2)
Gravity falls off according to the inverse-square law. So, to achieve 1/10 the force of gravity, you need to get sqrt(10) times as far away from the center of gravity of the planet. So we have to get just over 3.1 times as far from the center of gravity as we currently are.
So, how far from the surface is that? Let's assume that the planet is a perfect sphere of uniform density, which will make the center of gravity (co
Re: (Score:2)
Some materials are engineered for compression, such as the hollow bricks you so often see, and other materials are engineered for tension... a rope can't hold itself upright, it will fall down and fold, and if you try stretching a brick you will simply break a piece off of its edge.
Go play some Pontifex or Armadillo Run... it makes this sort of physics a tad more intuitive
Re: (Score:2, Insightful)
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 appropri
Re: (Score:2, Insightful)
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
Re:Other end? (Score:4, Informative)
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.
Re: (Score:2)
A straight tower couldn't be built.
Re: (Score:2)
We probably could build a tower from known materials (eg stone which is really, really, hard to crush, hence cathedrals etc). However, a tower is not stable. It would fall over at that height, even with our current best engineering efforts. Unless you made it very wide. Very, very wide, as it needs to be at least 50 miles (70 would be better) high to be useful. Our current tallest buildings are less than 600m high (that's less than 1% of 50 miles).
The other
Re: (Score:2)
That brings up an intersting idea though - your tower could float at sea. Every 100 meters of tower decreases the material constraints on the ribbon - though not by that much.
Personally I think a space elevator on earth is a bad idea. The material constraints are too close to the scientific limit of carbon na
Re: (Score:2)
Re: (Score:2)
Re:Why not a moon ladder instead of a space... (Score:2)
This isn't even the biggest problem with your proposal.