Space Elevator Conference Prompts Lofty Questions

itwbennett writes "Even the most ardent enthusiasts gathered at the annual Space Elevator Conference on Friday don't expect it to be built anytime soon, but that doesn't stop them from dreaming, planning, and trying to solve some of the more vexing problems. One of the trickiest questions is who's going to pay for the operational costs when an elevator is eventually built. 'It's been nine years we've been looking for someone' to study that, said Bryan Laubscher, one of the leading space elevator enthusiasts and principle at Odysseus Technologies, a company working on high-strength materials."

Comments

plasma cone what?

[AwesomeMcgee]

atmospheric re-entry be damned, let us consumers pay the maintenance in the form of skydiving tickets!

Re:plasma cone what?

[Anonymous Coward]

you're such a stupid nigger i can't believe it

An excellent example of a tautology.

Lofstrom loop is better

[Anonymous Coward]

Lofstrom loops ares well described on the wiki page for them. Check it out.

SPACE CADET (IN TRAINING) - WHERE DO I APPLY ??

[Anonymous Coward]

I am ready to run this elevator to space !!

Re:SPACE CADET (IN TRAINING) - WHERE DO I APPLY ??

[ozmanjusri]

WHERE DO I APPLY ??

Just go to North Haverbrook.

Or build a skyhook

[MichaelSmith]

It needs to be strong but nanotubes aren't required. You make a cable about 1000 km long. It has fittings on both ends which vehicles can attach themselves to. It orbits slightly more than 500 km above the ground and rotates its its axis horizontal and at 90 degrees to its orbit. The length and orbital altitude and chosen so that when one end almost reaches the ground it has a low velocity, while the other end is above escape velocity. You use it to exchange mass between the surface of the Earth and a trajectory which will take you to other planets. A dead mass can be sent down to Earth and a vehicle carrying passengers and supplies can be sent the other way.

Re:Or build a skyhook

[hedwards]

The idea is tantamount to expecting to go to the moon by pulling on your own boot straps.

In order for it to work, you'd need to have some energy source to resist the pull of the item you're wanting to lift into space. And by the time you start sending rockets up with fuel to do that, you might as well just use rockets to send the payload into orbit because it's much more efficient.

Re:Or build a skyhook

[Ramin_HAL9001]

How can you lift a 1000 Km cable into space, then control where one end of it lands? And how do you get a dead mass back up the other end once your shuttle has gone off and isn't available to counter-weight the dead mass that came back down when it was launched?

Re:Or build a skyhook

[strack]

thats a stupid idea. the sheer drag as it plows through the atmosphere repeatedly means itll last only a few orbits, if that. even if the speed was low, the drag would still be large enough to bring it down quickly. and anything you sling into orbit is gonna pull the entire thing down, so your gonna need the same, probably more, thrust to bring it back to that 500km orbit than youd spend just blasting a rocket with that payload on the same trajectory.

Re:Or build a skyhook

[Anonymous Coward]

go to the moon by pulling on your own boot straps.

Oh man, what if we connected the skyhook to the moon?

Nobel prize please.

Re:Or build a skyhook

[0123456]

thats a stupid idea. the sheer drag as it plows through the atmosphere repeatedly means itll last only a few orbits, if that.

I'm not entirely convinced. If you rotate it at the correct speed it could have zero velocity relative to Earth at the bottom of the swing and you could pick the orbit so that it picked up payloads in thin air (of course getting the payloads onto something that's rotating like that would be tricky).

Re:Or build a skyhook

[physicsphairy]

Well, one idea is that you catch random orbiting junk at the other end, replenishing the lost momentum. In any case, efficiency isn't particularly important. The major limitation on getting things into space right now is construction, launch logistics, etc. If we could somehow be continuously sending things into space, it would be well-worth having to send two or three times the fuel along with.

Re:Or build a skyhook

[KonoWatakushi]

Sadly, since a skyhook is not attached to the earth, it misses one of the key advantages of a space elevator: the earth itself supplying the necessary angular momentum. For an elevator, only potential energy must be supplied, and that rapidly gets cheaper the further up you go. Past geo-synchronous orbit it is entirely free, but velocity still increases linearly with height. (Keep in mind that the kinetic energy is proportional to the square of the velocity; paying for that energy directly is very expensive.)

With a skyhook, not only must you pay for the initial velocity, you can't arbitrarily choose the final delta-v, so there is still a considerable amount of energy that needs to be supplied, compounded with the extra fuel that must be carried to do so. Not to mention the continual input of energy to overcome atmospheric drag and maintain height. (If the up/down traffic isn't balanced, this is even more expensive, so you also need to consider the cost of moving that mass through space in the first place.) It would probably still be an improvement, but it would be complicated and could never hope to match the exceptionally low costs made possible by an elevator.

In terms of practicality, it may not require such exotic materials, but it would be that much more costly to orbit (and impart angular momentum to) such an enormous mass.

Re:Or build a skyhook

[Anonymous Coward]

"It has fittings on both ends [...]"

Since the device being imagined does not exist and may never exist in the form being contemplated, it would preserve your credibility a bit to use the subjunctive (sorry if I'm misusing the term). You should say, "It would have fittings on both ends" and so on.

Re:Or build a skyhook

[MichaelSmith]

The cable spins end over end. Attach masses to both ends at the same time. One mass at the top of the arc, the other mass at the bottom. Both masses match velocity with and end of the cable. During a half rotation the two masses exchange momentum.

Re:Or build a skyhook

[MichaelSmith]

Say you use it to send mass to the moon. For every 1000kg of food, fuel and people you send up, you send down 1100kg of lunar rock. This shifts the the centre of gravity of the rotating tether to a higher altitude every time two payloads are exchanged. Each end of the tether drops down to 10 or 20 km altitude, and at a low speed. Its motion relative to the ground would be mostly vertical. The amount of energy lost on each rotation would be fairly small and could be offset by importing rock from places outside our gravity well.

Putting the whole structure in orbit and spinning it up would certainly be expensive, but it might be possible to build it on the moon and send it down the gravity well.

Re:Or build a skyhook

[roman_mir]

What kind of stress is going to be exerted on that cable exactly? A structure of that size rotating, so it's accelerating all the time one way or another, are you saying it's easier to build a structure like that rather than a stationary cable that hangs from space?

Re:Or build a skyhook

[MichaelSmith]

Easier to build because it is shorter, and because stresses are lower it can be made with materials available today. A proper space elevator still requires the development of new materials. Stress on the skyhook would be complicated by the changing gravity gradient as it rotates, but it should be easy to model.

Re:Or build a skyhook

[Urkki]

The idea is tantamount to expecting to go to the moon by pulling on your own boot straps.

In order for it to work, you'd need to have some energy source to resist the pull of the item you're wanting to lift into space. And by the time you start sending rockets up with fuel to do that, you might as well just use rockets to send the payload into orbit because it's much more efficient.

There's power aplenty at the orbit, so just use ion or plasma propulsion, and send stuff up at frequency that matches the average lift generated. The amount of propellant sent up will be a tiny fraction of what current chemical rockets need to get a single kilogram to orbit. And if more capacity, more frequent lifts, are needed, then just strap on more engines, and/or send more stuff down to earth.

Re:Or build a skyhook

[Zontar The Mindless]

That's the conditional mood, not subjunctive (which occurs only in dependent clauses).

Were (subjunctive) such a structure to be built, it would have (conditional) fittings on both ends.

Re:Or build a skyhook

[IrquiM]

The weight of that cable sort of kills your idea before it starts....

Re:Or build a skyhook

[MichaelSmith]

Why? It only has to support itself against centrifugal forces and the gravitational gradient along its length. It could be assembled in orbit from smaller lengths of cable.

Re:Or build a skyhook

[OeLeWaPpErKe]

Or how about this simple way of doing things :

Orbits come in many sizes. Orbits close to geostationary orbits have the following properties :
if you are slightly closer to earth, you will fall down (slowly)
if you are at the exact right spot, you will stay there
if you are slightly further away from earth, you are in effect on an escape trajectory, you will gain height (slowly)

So here's an idea. Since this cable has to withstand umpteen giganewtons of tension anyway, place the top of the elevator too high. Therefore the cable will have to pull on the satellite to keep it in a stable orbit. Since a giganewton more or less doesn't really matter, let's add a giganewton. Then we can attach payloads of up to 100 tons to the wire without causing the satellite to fall down to earth.

Where does the energy come from ? It uses the rotation of the earth to pull satellites into orbit, so conservation of energy is effected by slowing down the earth for every satellite going up.

Also the whole point of a space elevator is that we don't need to carry fuel to put fuel into orbit. When the US launches the space shuttle, 50% of the fuel in the rocket is used up to give the rocket 1 meter elevation. Electricity is available everywhere if you've got millions to spend on hugely expensive solar panels (and millions would be *very* cheap for satellites). Rockets have 0.4% efficiency because most fuel is used to have a little fuel available higher up. With a space elevator at 50% efficiency, launch energy costs would go down a factor of 120 ...

And let's not forget that a space elevator would make space-based solar power a braindead endeavour, so it would probably pay thousandfold for it's energy expenditures anyway. An operational space elevator would be even better than working fusion power.

But imho a better and easier option would be to get a working fabrication facility operational on the moon. Your mother can knit a working space elevator for the moon together easily, and her grandson is probably operating a catapult capable of launching satellites into earth orbit from the moon surface near some people he doesn't like. So another easy option would be to simply fabricate satellites on the moon. It would have the additional advantages of massive free amounts of solar power, easily mineral stores you wouldn't believe, and you can easily get to the rest of the solar system in addition to earth orbit (which would still require a relatively big rocket starting from earth geostationary orbit).

Re:Or build a skyhook

[bill_mcgonigle]

It needs to be strong but nanotubes aren't required. You make a cable about 1000 km long.

What's it going to be built out of, then? Nobody's ever build a 1000km long anything, much less a something that can support its own weight in Earth's gravity field.

Re:Or build a skyhook

[Anonymous Coward]

Nobody's ever build a 1000km long anything, much less a something that can support its own weight in Earth's gravity field.

Does this count?

Re:Or build a skyhook

[gd2shoe]

Oh bother. The moon isn't geosynchronous. You're going to have a base station that follows the moon around? Crossing the planet apx once every day, including oceans and continents?

Either the cable would snap, or it would become the worst game of tetherball ever!

Re:Or build a skyhook

[Anonymous Coward]

I assume by rock, you mean metal bearing ores / asteroids? so at least we can continue to fuel the USian consumers ...

Anytime soon

[perpenso]

Even the most ardent enthusiasts gathered at the annual Space Elevator Conference on Friday don't expect it to be built anytime soon

Considering that the engineers who will design and build the elevator first need the scientists to figure out the physics and chemistry of the materials required that is a pretty good perspective.

Re:Anytime soon

[hedwards]

Projects like this are frequently as interesting, if not more so, for the byproducts that have to be developed in order to make it work.

Re:Anytime soon

[tmosley]

Christ, it's like I'm in the 90's. Has no-one in this thread heard of graphene?

Re:A virus!?

[Anonymous Coward]

Comments are ignored by Google, you stupid asshole.
Do humanity a favor and set yourself on fire.

Re:A virus!?

[Anonymous Coward]

I second a Spammer Burning.

Elevator to nowhere

[Osgeld]

I get that people want to nerd out and iron the issues out on such a wacky idea

but seriously?

"One of the trickiest questions is who's going to pay for the operational costs when an elevator is eventually built"

its never going to be built! cause its fucking stupid idea, and because outside of a serious brain exercise it holds no value

Re:Elevator to nowhere

[wmbetts]

Fine then! When it's built you can't ride it!

Re:Elevator to nowhere

[The Pirou]

Lots of things have sounded stupid by outsiders as demonstrated by the vilification of Galileo by geo-centrists. Should he have let them stop him?

By getting together and starting broader dialogue about the idea of creating a viable mechanism for transit these people are at least working on the 'pseudo-code' for the problem. Whether this particular idea should fail or not, the solutions presented have the potential to act as a fulcrum for broader scientific discovery. Scientific revolutions don't happen by deciding not to attempt to pursue something because it sounds silly given your current understanding of the world around you.

Re:Elevator to nowhere

[Baloroth]

Do you know anything about space elevators? Seriously. They're a great idea. Practically speaking, they are also very difficult, but if we could build one, the cost of traveling to orbit would become relatively speaking extremely cheap (technically, the energy requirements would stay the same. But the delta-v required would become as low as we please, making very cheap and low-power sources effective). Long term, unless we find a much better way to get to space, they are very likely to be built.

I agree that that is a very stupid question. Obviously, whoever uses it would pay for its use. Aka, commercial companies, NASA, military, etc. Since lots of people want to put stuff into space, lots of people could fund its operation .Probably it would be run by a company or government who would charge for its use (preferably, there would be at least two to introduce competition). That part is relatively easy. Its construction, on the other hand, is quite a problem. Financially and technically. However, it is a very good idea. Keep in mind, 150 years ago space travel on rockets was also just an idea in a few peoples minds. Turns out it isn't such a bad idea after all.

Plus, having an actual stairway to heaven would be pretty awesome...

Re:Elevator to nowhere

[Anonymous Coward]

"if we could build one"

How about we get to the point where we can build a bridge over a valley somewhere with carbon nanotubes first. Even that is a LONG ways out. Not any of our lifetimes. And that bridge is about 10000X easier to build than a space elevator.

In theory, it's workable (just barely). In practice, the engineering is so far beyond us that it might as well be impossible.

Re:Elevator to nowhere

[Anonymous Coward]

The Space Elevator will be built:

"50 years after everyone stops laughing"

Sir Arthur C. Clarke

Re:Elevator to nowhere

[Osgeld]

well right there in the article its talking about driving cars up it ... never mind the MILES of gravity its seriously talking about cars driving up it

Re:Elevator to nowhere

[Osgeld]

yea like driving cars up it as in TFA, you have MILES of gavity to defeat and these clowns forgot gravity

its now how I see the world that makes it stupid, its the god damned facts of the world that makes it stupid

Re:Elevator to nowhere

[Anonymous Coward]

yea like driving cars up it as in TFA, you have MILES of gavity to defeat and these clowns forgot gravity

its now how I see the world that makes it stupid, its the god damned facts of the world that makes it stupid

Do you imagine some redneck in a v8 with a gun rack on the back taking his tractor tired 4x4 up a vertical road? Seriously.. the word car can be more than just "automobile" ..

Re:Elevator to nowhere

[Osgeld]

um yea number one definition of car is automobile followed by trolly, just because in your firefly rerun world car != automobile does not make up for the fact that for the last 100 or so years car = automobile

k thanks

Re:Elevator to nowhere

[Anonymous Coward]

When they say "cars", they don't mean automobiles. They're using the word in the same sense as an elevator car - a moving container holding people or other things.

Also, you don't measure gravity in miles.

Re:Elevator to nowhere

[Anonymous Coward]

Nowhere in your little rant did you address the fact that the TFA's use of the word car doesn't mean automobile. I take it you've never heard of train cars or elevator cars? Hint: "elevator cars"..."space elevator"...notice the connection?

Re:Elevator to nowhere

[The Pirou]

Don't limit your perspective.
Have you seen 'Minority Report?' Their interpretation of future 'roads' is like a public mag-lev bullet train taken to the individual level. Granted, that's not necessarily the way we're progressing, but it still follows that it's a possibility. Again, this is about writing the 'pseudo-code' that might yield something positive in the future, and deriding it as a wacky idea that shouldn't be taken seriously warrants a "seriously?" itself.

Re:Elevator to nowhere

[oldhack]

Yep, these people make UFO space aliens fanatics look like Lutherans.

Re:Elevator to nowhere

[Arlet]

Space junk is already becoming a problem. Imagine what would happen if it were extremely cheap to put stuff in orbit...

Re:Elevator to nowhere

[dvice_null]

"The aeroplane will never fly."

— Lord Haldane, Minister of War, Britain, 1907 (yes, 1907).

"No flying machine will ever fly from New York to Paris ... [because] no known motor can run at the requisite speed for four days without stopping."

— Orville Wright, c. 1908.

"The whole procedure [of shooting rockets into space] . . . presents difficulties of so fundamental a nature, that we are forced to dismiss the notion as essentially impracticable"

— Sir Richard van der Riet Wooley, British astronomer, reviewing P.E. Cleator's 'Rockets Through Space,' in Nature, 14 March 1936

Re:Elevator to nowhere

[0123456]

In practice, the engineering is so far beyond us that it might as well be impossible.

Nearly impossible? OK, we might have to wait two hundred years then.

Re:Elevator to nowhere

[Osgeld]

yea thanks I dont get my future vision from made up bullshit in a special effects house, the age of sifi actually having a real influence on tech is gone, sifi has gotten even more outlandish with its bullshit, and tech has cought up to the point where some dev at apple thinking that compressed music in a large archive is the way of the future, is long gone.

so enjoy your movies past of futures that will never be, I personally will be doing the best I can with what is available

Re:Elevator to nowhere

[Anonymous Coward]

space junk is only a problem for people who go to space, you are arguing that we should not go to space to avoid space junk, which would also assure that no one would be there to care about how clean the orbit is.

Space junk problems can be dealt with, and will have to be if we are going to leave earth.

I hope it is so cheap to put stuff in orbit that a freaking junk ring visible in the light of day forms.

Re:Elevator to nowhere

[nmb3000]

well right there in the article its talking about driving cars up it ... never mind the MILES of gravity its seriously talking about cars driving up it

I used to be very critical of space elevators as well... until I bothered to read up on the ideas behind them. If you're actually interested in learning more, check out these two articles:

Space Elevator
Space Elevator Economics

As just a quick example, putting a payload in orbit with rockets ranges from $4,000/kg to $40,000/kg depending on the rocket type. Estimates for the cost of electricity to move an elevator into orbit is around $220/kg with current power transfer capabilities, becoming cheaper as that technology improves. And, if you assume that power becomes cheaper to produce in the same timeframe as space elevator components become feasible (ala fusion or something else), this payload delivery cost will be even lower.

Nobody is suggesting we break ground on the base stations today. It's simply an interesting idea for putting things in orbit, and maybe a good goal/benchmark for the development of new high-strength materials.

Re:Elevator to nowhere

[Arlet]

you are arguing that we should not go to space to avoid space junk

No, I didn't.

Re:Elevator to nowhere

[Anonymous Coward]

The sunk costs of a space elevator would be fucking gigantic, though (18 billion? So, what, figure on 180 billion when it's finally budgeted and 10 times that to get it finished?) How do you price it in that case? If you price it above the cost of a rocket, you get nothing and you go bankrupt. If you price it too low and demand doesn't keep up with your plans, you still go bankrupt.

This could end up being another Iridium, if it ever happens and is expected to be self-supporting. The initial investors bear almost all the cost, the project goes bankrupt, then is sold for a fraction of what it actually cost to the parties who will run it profitably (because they didn't pay the cost of building it).

Re:Elevator to nowhere

[sunspot42]

The Shuttle program and the ISS alone have cost us north of $200 billion.

With a space elevator, you could conceivably haul the components to build something as large as the ISS into orbit in just a month, for less than the cost of a single Shuttle launch.

Given that the cost differential between launching on chemical rockets and hauling cargo up on a space elevator is THOUSANDS of dollars a kilogram, you can pretty much guarantee that a space elevator will turn a profit. It'll cost around $200-$300 a kilogram to haul payload into orbit with a space elevator, compared to $4,000 and up - way up - with rockets. The operators of a space elevator could charge $3,500 a kg and pretty much monopolize the entire launch business, pocketing $3,000 a kg with each payload.

At least until somebody else builds a space elevator...

Re:Elevator to nowhere

[Anonymous Coward]

Are they referring to the road-type of cars, or something more similar to ski-lifts? The orbital tether from Star Trek Voyager comes to mind.

Re:Elevator to nowhere

[Anonymous Coward]

Pointless talking to him, he's trolling...

he's had the explanation a few times and he's still intentionally stupid...

Re:Elevator to nowhere

[vlm]

"if we could build one"

How about we get to the point where we can build a bridge over a valley somewhere with carbon nanotubes first. Even that is a LONG ways out. Not any of our lifetimes. And that bridge is about 10000X easier to build than a space elevator.

Not really. CF is basically "really weak nanotube". CF doesn't burn too well in a vacuum, and there are not many vandals in space, or at least you can put a guard shack at the base and be done with that issue.

There are "many" CF bridges, at least in the USA. Mostly corrosion proof, you tend to find them up north in "road salt country". I can imagine, within my lifetime, we will no longer use steel rebar in concrete.

The problem with purely CF bridges, is to stop vandals with no more than a hunting knife from collapsing the bridge, or stop a simple vehicle fire from incinerating the bridge, you have to encapsulate the thing in concrete, which of course in freeze/thaw cycles delaminates from the CF, or sticks to the surface of the CF making the CF delaminate, etc.

People get real confused about CF and give it mystical properties it does not have. It has spectacular, record breaking tensile strength, yes. Surface hardness? No, not like diamond, in fact its about as hard as charcoal WRT to dulling cutting blades. Abrasion resistance? No, not like stainless steel, more like the plastic resin its bonded with. High temperature strength? No, not like tool steel, more like the plastic its bonded with. Bullet proof? Yeah about as bullet proof as an equal amount of plastic. It's just about unstretchable, but otherwise you may as well think of it like plastic.

Carbon based bridges are a huge mess, not because carbon based structures suck, but because vandals suck, and gasoline automobiles suck.

Re:Elevator to nowhere

[ProzacPatient]

If you think this is impractical then why are you on Slashdot then?

Re:Elevator to nowhere

[shoehornjob]

The funding for the first space elevator will be so massive that it should be paid for by a consrtium of companies and government agencies. This is no different than funding other large scale projects in space (ISS for example) and if we are going to get to Mars it will be together.

Re:Elevator to nowhere

[Darfeld]

Seriously? "The future is done, let's get to rest and enjoy!"?

Will I'm all for the "enjoy" part, thinking that no tech revolution will happen anymore is just as ridiculous as buying a flying car for next year.
Look the prediction for the future along all the twentieth : It's 90% bullshits (certainly more so...). They even wanted you to eat radioactive materials as a way of keeping health! How can you talk about "the age of sifi having a real influence on tech"? There was never such an age more than nowadays.
So okay, maybe a space-elevator won't be build, but you have lots of science fiction materials being done : Invisibility cloak! cybernetic limbs! 3D TV!
Those are maybe not exactly as good as what you would like them to be, but they exist and are being build! (and even more ! some are actually commercialized!)

Science fiction product bullshits, it's ok... Part of why one read it is that it's about think not possible with our understanding of science, speculated with what the author do know about science. Some of them are cool enough that people actually try to realize them, and sometimes they succeed. Sometimes not. But anyway, technologies doesn't need science-fiction to evolve. Science fiction exist because people think about what can be done, or what could be cool(or... very not cool) if done. It's not preliminary research. If anything, it's popular brainstorming coupled with stories. You don't ask science fiction for doable stuff with practical application, it's just lame...

Re:Elevator to nowhere

[tmosley]

Space junk is a problem in NEO, not geostationary and above, which is where the space elevator goes.

Re:Elevator to nowhere

[Arlet]

Space junk is also a problem in GEO, because it tends to concentrate in a narrow useful orbit. The only advantage is that relative velocities are small, so damage from collisions is not as severe. On the other hand, lack of atmospheric drag keeps the junk in orbit for much longer.

https://secure.wikimedia.org/wikipedia/en/wiki/Space_debris#Debris_at_higher_altitudes

Re:Elevator to nowhere

[tmosley]

Hence "not a problem". If it gets too crowded, then you have raw materials (actually refined materials) to build a geosynch space station all the way around the planet.

Re:Elevator to nowhere

[KahabutDieDrake]

The difficult we do immediately. The impossible takes a little longer.

Re:Elevator to nowhere

[KahabutDieDrake]

If, as you suggest, it would be paid for by a large consortium of companies and governments... I think you'll find that Mars is not the target, but Jupiter is. I can almost taste the hydrocarbons already.

Re:Elevator to nowhere

[selven]

technically, the energy requirements would stay the same. But the delta-v required would become as low as we please, making very cheap and low-power sources effective

It's even better than you think. The fuel needed to accelerate a spacecraft to escape velocity (and the container to carry it) is very heavy (at an exhaust velocity of 4.5 km/s, fuel to get from surface to deep space (11.3 km/s delta-v) is nearly 10x the weight of the rest of the fuel and the payload), but with space elevators all the "fuel" is stored on the ground, so you actually need 90% less energy.

Re:Elevator to nowhere

[Risen888]

Discounting the entire idea of human presence in space, a space elevator would still hold tremendous value in making satellite launches orders of magnitude cheaper. Big chemical rockets are obviously a shitty, grossly wasteful answer to that problem.

Re:Elevator to nowhere

[Risen888]

PROTIP: The shift key makes capital letters.

Re:Elevator to nowhere

[pokechop]

Thank you, GT. -Norman Niblock House

Re:Elevator to nowhere

[cusco]

Still cheaper than what we spent on destroying Iraq. For that matter, still cheaper than any number of military boondoggles that server no purpose but making the manufactures of war toys rich.

$18B

[Swanktastic]

The article suspects a space elevator could be built for $18 Billion? And they're worried about doing a study to explore who will pay for it? That much money is budget dust for any major country. Once the technology is there, I'm sure Boeing or Bechtel will be more than happy to take taxpayer money to work on the project and "create jobs."

Re:$18B

[Anonymous Coward]

That number is way lowballed. What, are they thinking the price of the nanotube cable is comparable to the market price of carbon?

Anyone dumb enough to pay to build a space elevator this early in the game will lose their money.

Seriously, it's an elevator from the ground to one point in geosynchronous orbit. A payload released at almost any other altitude will need reaction mass to establish a stable orbit, most of which will be expended in the direction of the cable and thus wear it down. (The exceptions are payloads released near geosynchronous orbit which will establish elliptical or parabolic orbits.) Finally, other satellites and debris at lower orbits especially, will impact the cable, both damaging it and setting up waves which will need to be safely dissipated somehow. A paint chip at 500 miles up is going to hit at around 17k miles/hr. and will have plenty of kinetic energy that needs to go somewhere.

Commercially, this is useless, even if you could build it easily and cheaply. It's an engineering nightmare, and no amount of focus on the easy parts of the design -- and the material is the easy part -- will change that.

Re:$18B

[TaoPhoenix]

AC below has key points, but I am responding to you in a different vein.

I'll let you have your 18 billion to build it, but it's the "leading edge" of another 100 billion in support industries. "A Cable to lift what? To where?"

Re:$18B

[myowntrueself]

The article suspects a space elevator could be built for $18 Billion? And they're worried about doing a study to explore who will pay for it? That much money is budget dust for any major country. Once the technology is there, I'm sure Boeing or Bechtel will be more than happy to take taxpayer money to work on the project and "create jobs."

Sure, the Yanks could borrow some more money from China.

Re:A virus!?

[Anonymous Coward]

mmm burnt spam!

No usable tether in sight

[Anonymous Coward]

The elephant in the room is the tether. As long as there's no tether a few meters long in a labarotory, you don't even have to think about any other aspect of a space elevator.

Re:No usable tether in sight

[tmosley]

1 meter long graphene ribbons have been synthesized, and the length of those ribbons are only limited by the fact that it was a lab scale experiment. In a few years, graphene will be mass produced at rates that will make a space elevator tether trivial to produce. The tensile strength is above the required amount, and it is far FAR more reproducible than some dumb 90's tech like carbon nanotubes.

The major issues and such

[JoshuaZ]

Anyone interested in this issue should read the NIAC report http://www.spaceelevator.com/docs/521Edwards.pdf which discusses the issues in detail and the technical problems. Space elevators would make space travel much cheaper. But the technical issues are immense. The NIAC report carefully outlines the major issues and how they might be handled. We would need to make extremely high quality carbon nanotubes at an immense scale. We also would need to put into space a structure orders of magnitude larger than anything we've put in space. Indeed, a space elevator would be one of the largest physical structures ever made by humans. And the engineering hurdles, such as the problems of wind in the lower atmosphere, are massive. But there's nothing about the idea that is physically impossible. The primary issues are issues of scale. And the issues are being worked on. Right now, there's a lot of work on making carbon nanotubes of high quality in a large scale. Since such nanotubes would have many different applications there's a lot of funding for that and that will likely be extremely beneficial to humanity well before it scales up to anything near that needed for a space elevator. Since the nanotube manufacturing is the primary technical hurdle, this is a good thing. I doubt we will see a space elevator in my lifetime, but maybe my children, or their children, will see it. And on that thing ribbon, space travel will finally become as cheap as so many have envisioned it.

Re:The major issues and such

[JoshuaZ]

And on that thing ribbon

Ugh. Need to pay more attention to preview. Replace "thing" with "thin".

Re:The major issues and such

[Anonymous Coward]

We also would need to put into space a structure orders of magnitude larger than anything we've put in space.

So all they need to do is build a second space elevator to put it up there...

Re:The major issues and such

[Anonymous Coward]

There's one issue, that makes a space elevator impossible:
The immense voltage difference between the Van Allen belts and Earth's surface will, the second a space elevator is in place, or possibly shortly before, create a lightning strike many orders of magnitude stronger than any recorded before.
A huge area around the tether point would be completely obliterated.
http://www.thunderbolts.info/tpod/2006/arch06/060322sprite.htm

Re:The major issues and such

[Anonymous Coward]

I would add political issues to the major problem list.
From a technical/financial perspective it is unlikely that any country can do this on its own. But even when someone can, other countries would most likely have objections against it. Some of those objections will be serious and valid.
Add that the elevator will be immensely vulnerable and it is obvious that global political consensus has to be reached, either to help build it or to make sure none sabotages it.

Does a space rope have the same physics?

[GoodNewsJimDotCom]

Imagine a large object with thrusters orbiting with a rope dropped from it. I'm thinking that the top of the rope must be able to hold the tension of the entire rope, thus it is the same thing as the base of an elevator holding up the entire weight, correct? This is just something I wondered about.

Re:Does a space rope have the same physics?

[Ironchew]

From my cursory understanding of space elevators, the section in geostationary orbit will have the most tension (and subsequently the most cross-sectional area for handling that tension), and the center of mass will be at geostationary orbit, which possibly involves a tether going down to Earth and something else of equal mass in high Earth orbit. Presumably, the weight of the lower end will be canceled by the centrifugal force of the upper end.

Re:Does a space rope have the same physics?

[hedwards]

That's really a problem, you need to expend energy to keep the satellite in orbit and you need to have energy to raise the payload. Which unfortunately, is liable to be source of the fuel to keep the satellite in orbit. If you've got another means of fueling the satellite to keep it in orbit, you're probably going to be better off using that to get things into space.

Trying to use cable under tension in a scenario like this is never going to work without a major revision to the laws of thermodynamics. It is how ever conceivable that something like this could be achieved with an exceptionally tall tower. Which would be extremely difficult to do, but is at least within the realm of possibility as the force to keep everything in place would come from compression rather than tension.

Re:Does a space rope have the same physics?

[dbIII]

I think the idea is stuff crawls up the outside in a more efficient manner than a rocket throwing stuff out the back and if enough cargo goes up then more can be more than would be possible merely with the fuel for the rockets used at the top or other point to keep the entire thing in station.
Of course the fanboys never get as far as even considering that! It's all free energy to them because rotation confuses them and they forget that gravity is going to be greater than outward acceleration on such a structure at any point below geostationary orbit.
The last time this topic came up some very insulting idiot insisted you just hook your cargo onto the cable and it magicly goes up like an Indian rope trick. Rotating frames of reference really screw with peoples heads and they forget that's a really simple one dimensional problem with just varying acceleration to fight against at different points on the line. If they would just look at the wikipedia page on these beanstalks they would see a simple equation for that acceleration and get an idea of what something ascending would have to do.

Re:Does a space rope have the same physics?

[LBU.Zorro]

Sigh.

The whole point of a space elevator is that the centre of mass of the cable is at geosynch orbit (well slightly past it). There is no need to continuously thrust to hold the cable up because the rotational speed of the planet will fling away the cable.

The reason that the cable stays up is the gravity drops off by the square of the distance but distance travelled by the cable per hour at any height increases. The period of rotation is always 24 hours (give or take some lean) but the circumference described is greater as the height increases.

What this means is that at geosynchronous orbit the force downward due to gravity (at that distance from earth) exactly matches the centripetal forces from orbiting the planet (or more accurately attempting to fly off in a straight line but the gravity of the planet curving that line).
Below geosynchronous orbit if you are orbiting the earth once a day you're doomed to crash into the planet without active energy input (the rate of curvature is higher than your speed thus you'll hit), above geosynchronous orbit if you're still orbiting the earth once a day you're doomed to escape the planets' gravity altogether and go flying off as you spiral out. This is why low orbit satellites orbit so quickly and high orbit satellites orbit so slowly, the relative strengths of gravity at the different orbits, plus the distance travelled to complete an orbit dictate the speeds.

The parts of the cable that are above geosynchronous orbit are attempting to escape earth, and the parts of the cable that are below geosynchronous orbit are trying to crash down to earth - the reason the cable stays up is that these are balanced. The entire weight of the cable (less the reduction due to centripetal forces) below geosynch (and adding the tension in the cable necessary to lift a weight) is indeed all passed through the portion of the cable in geosynch orbit (it's actually a huge section as 1 metre from geosynch either way isn't much difference). But the cable isn't a cable, at least not in current designs, it's a ribbon varying in width from thinnest at the ends to widest at geosynch as the loads vary - there are also thickness variations due to expected damage to the cable, ie at certain orbital levels micro-meteorite (and space junk more likely) impacts are very likely so the cable would be made wider to compensate.

Please note that this doesn't allow anything to be pulled up the cable, it is just supporting itself, what you need to do is stick a nice big weight on the end of the cable on earth, like say the base station weighing in at hundreds of tonnes (but not supported by the cable, supported by the earth's surface) and then extend the cable upwards until it has a tension high enough to do something useful. The tension in the base of the cable where it meets the base station will be at least the weight of anything you want to send up the cable (and have more because acceleration increases the force).

The real problem with understanding this is that humans live on such a small height variation and deal with speeds so slow that you cannot easily imagine what happens to gravity over those distances and how much energy is involved in those speeds - if you accept that orbital mechanics isn't the same as you running about on earth it becomes much easier to understand.

No revisions of any laws (other then potentially materials sciences as we don't yet have a material that has a strong enough tensile strength but low enough weight) are required for this to work, all you need to do is understand them.

The 'energy' you use to raise the payload is electrical converted to kinetic converted to gravitational potential. If there happened to be a mountain of a magical material that reached out into space then climbing that mountain would not violate any laws of thermodynamics.

Towers have problems, compressive strength vs weight, mechanical strength of the earths crust, and major issues with stability. Compression is a positive runaway scenario (the tower bends slightly and the weight causes the bend to accelerate), tension has a negative (or neutral I suppose) runaway scenario (the cable bends and the cable tries to straighten out).

Z.

Re:Does a space rope have the same physics?

[KahabutDieDrake]

My understanding is that centrifugal forces, combined with ION engines (or similar) would keep the satellite station up and in place. Of course, this sort of design requires the cable be nearly twice as long as it actually needs to be, and sending the other half out to suck up weight (through centrifugal force). Or even anchoring some dark matter (whatever is heavy enough) to the far end which we send out to high orbit. Also, I think you seem to be under a mistaken impression about the amount of force generated by sending off a "tail" of the cable into high orbit. Especially with any weight on the end of it. Now, I'm certain, through some simple experiments here on earth, that such a system works just fine. Ever used a Bolas? Anyway, from my ameture perspective, I'd assume that your biggest problem would be the "tail" either going faster or slower than the satellite station itself, which eventually leads to the cable snapping back, which, presumably, would be unpleasant.

Re:Does a space rope have the same physics?

[LBU.Zorro]

No need for ION engines (not sure why that's capitalised) to hold anything up - the forces on the cable beyond geosynch pull the entire cable tight, about the only use for the ion engines would be (and this is any type of reaction thruster) to help damp oscillations in the cable.

You are correct, the cable is much longer than it needs to be (more than twice I believe, geosynch is roughly 35k km up and the designs I've seen talk about a 100k km cable) mostly due to the requirement for lifting tension and the fact that the cable is incredibly light for it's length, in the order of grams per km.

An easier (for a given value of easy) would be to have a large mass (it's a measure of mass / distance past geosynch - no need for dark matter when a rock will do) a distance beyond the geosynch to counter-weight, either way it works - the forces on the cable past geosynch cause the cable to stick out straight, perpendicular to the surface of the planet and will always attempt to get that as straight as possible.

Don't worry about the cable snapping going too fast or too slow, as it happens as you have a weight travel down the cable the cable will travel ahead of the rotation of the planet, as something climbs the cable the cable will lean behind the rotation of the planet - effectively there's an east-west acceleration as the weight descends / ascends the cable. This has the effect of pulling the cable down fractionally but the excess tension also pulls the cable back up again, it won't be instant or 'snapping' as there's never any massive horizontal displacement / force - the speed of the climber dictates the rate of change of circumference/orbit and thus the horizontal force applied to the cable.

The tail won't really get ahead of behind of the 'station' (there won't actually be a station as far as I know) as the cable will attempt to remain straight from the point of horizontal deflection. There will be vibrations and other variations travelling up and down the cable but they should both damp in time and be damped dynamically.

One last thing to remember, most of the cable is outside of the atmosphere so there's no atmospheric drag (well, vanishingly small as it's not exactly a pure vacuum) on the tail to add to the problems.

It's a hard engineering challenge and we've not got the materials to do it yet but it'll change a lot when it (or something like it) does happen.

Z.

panax

[Anonymous Coward]

object with thrusters orbiting with a rope dropped from it. I'm thinking that the top of the rope must be able to

Re:panax

[PwnzerDragoon]

Shit, we lost another one. I keep telling them to be more careful where they drop those ropes.

Pfft

[Anonymous Coward]

A space elevator is a ridiculously absurd idea. Next some goofball scientist will propose a pneumatic tube to Mars. Pfft.

Realistic that carbon nanotubes won't cost much

[Anonymous Coward]

That number is way lowballed. What, are they thinking the price of the nanotube cable is comparable to the market price of carbon?

They were probably thinking that the US and Europe will spend 100s of billions in R&D to discover the science, engineering and manufacturing processes necessary; then China will just rip off the research and manufacture at prices that only need to reflect the actual production costs.

Please Mod Parent Up

[Anonymous Coward]

Launch Loops are indeed far more interesting and practical. Can anyone here explain why space elevators seem to be the more popular idea among the two?

Re:Please Mod Parent Up

[siddesu]

It could have something to do with the price tag of maglev tech, which is a little over a brazillion gazillion trillion million dollars per mile of tracks, one way. And I am not even touching the 80 mile high bridge that will have to support it. I'd say at this stage both projects look equally practical.

Re:Please Mod Parent Up

[Rei]

A couple hundred miles of maglev track versus tens of thousands of miles of unobtanium cable exposed to micrometeorites, space debris, undamped oscillations, etc. Hmm, which is more realistic...

And I have no clue what you mean by "80 mile high bridge", except to assume that you've grossly understood how a Lofstrom loop works.

The key issues are:

1) A Lofstrom loop requires no unobtanium. It may well be *physically impossible* to create the material needed for a space elevator on Earth, let alone economically practical. After all, the strongest *invididual SWNTs* measured thusfar were barely over 60GPa at the density of graphite, when you need a *bulk cable* that's ideally over 100GPa at graphite densities, preferably over 120.

2) A Lofstrom loop transmits power (the primary lift cost from both systems) at about 50% efficiency. A space elevator beams power at a couple percent efficiency. Hence a Lofstrom loop costs an order of magnitude less to operate.

So we're back to the start. Why a space elevator, apart from the fact that everyone knows of it through sci-fi? Wait, I think I answered my own question.

Re:Please Mod Parent Up

[mosb1000]

A space elevator is essentially a static structure, it does not require any power to stay in place. As such, it is more like a building than a machine. It's much less complex, which means quality control would be much simpler/possible. There are many questions about how you would build a launch loop too. The only real question about a space elevator is the material. They think single walled carbon nanotubes could be strong enough to do the trick. That means the technology is more likely to pan out in the long run. And if you could build it, it could be much cheaper to operate and much simpler to build than a launch loop.

So, in short, the space elevator gets more attention because it is a more compelling proposition, and seems more likely to succeed.

Re:Please Mod Parent Up

[siddesu]

Yep, you're right, I did not perceive the genius at first, I just lazily looked at the picture. In fact, there is no bridge, the structure sustains itself by its own momentum, gravlevitating or whatever. Good luck building that kind of structure without Unobtainium and at only the small price I quoted in my previous post. A 80-km tall bridge won't be much harder.

Re:Please Mod Parent Up

[Ihmhi]

Can anyone here explain why space elevators seem to be the more popular idea among the two?

Launch loops weren't featured in a Gundam series.

Re:Please Mod Parent Up

[maxwell demon]

It's more inspiring. Launch loops wold be just another launch technology. Space elevators are something completely different. If you read the term, in your mind the idea forms that you go into space with the same ease as you go to the upper floors of a high building. A launch loop doesn't provoke that image.

Re:Please Mod Parent Up

[Darfeld]

What about the fact that Space elevator allow easy atmospheric re-entry and the launch loop does not?

Re:Please Mod Parent Up

[tmosley]

Unobtanium? Graphene is already known to exceed the tensile strength required for a space elevator. Get with the program. Nanotubes are 90's tech. Now all we have to do is get mass production methods running, at which point the ribbon becomes trivial, though the deployment and climbers remain troublesome. I personally like the idea of simply attaching the "climber" to the ribbon at the base station, and letting the centripetal force of the earth push the ribbon out into space along with the climber, brings all the moving parts onto the ground where they are easy to deal with (no getting stuck 900 miles above the Earth's surface due to mechanical failure).

Re:Please Mod Parent Up

[Ken_g6]

The other problem with a space elevator is that it's rather impractical to build a small one. If you don't go out to geostationary orbit, it doesn't work very well.

On the other hand, imagine a small Lofstrom loop (or similar device) that goes only a mile or two high. Next, imagine placing it at an amusement park (e.g. Disney World), and letting guests ride it all the way up and down (at sub-orbital speeds, of course). That's one heck of a Ferris wheel! (The current tallest Ferris wheel in the world is only about 0.1 miles high.)

Re:Please Mod Parent Up

[evanbd]

I think you underestimate the control problems inherent to very long, very flexible structures that need to move to avoid debris. It's a lot more like a machine than it looks at first glance.

Re:Please Mod Parent Up

[mosb1000]

The elevator would be under an enormous amount of tension, moving it to avoid debris is not realistically possible. The plan I'd heard was to make it a thin strip so that debris would puncture only a small part of it, and then design it is such a way that it would be repairable over time. Also, you may have noticed that putting a cable under a lot of tension renders it significantly less flexible.

Re:Please Mod Parent Up

[evanbd]

This cable is ridiculously long. There's a wide range between "really stiff and not flexible" and "infinitely stiff, or close enough that you don't have to worry about it", at least when it comes to space elevators. This pageseems to hit a few of the major points. There's plenty more out there.

Tolerance of micro-impacts is clearly required; you can't watch out for everything. But there's a significant amount of debris out there that is large enough you need to watch out for it. Your choices for handling it will tend to involve moving either the elevator or the debris; moving the elevator might turn out to be easier. Note that moving a tremendously stiff cable a distance of 10^-6 times its length is not that big a deal. The hard part is the dynamic stability control.

Re:Please Mod Parent Up

[Grishnakh]

personally like the idea of simply attaching the "climber" to the ribbon at the base station, and letting the centripetal force of the earth push the ribbon out into space along with the climber,

Huh? Centripetal force, for one, pushing things towards the center of rotation. Maybe you meant centrifugal force. Either way, that won't work either, because of this thing we call gravity. Ever wonder why the earth's rotation isn't throwing you off into space? Please tell me you were kidding, or that this was very badly-written.

The big problem with the space elevator, as I understand it, isn't really making the ribbon, it's:
1) keeping the ribbon from being damaged by all the micrometeorites, space junk, etc. that is up in orbit. Remember, the ribbon has to stretch from the ground up to something like 60,000 miles, and doesn't have any protection from the atmosphere along all but ~200 miles of its length.
2) getting power to the climbers in an efficient manner. The current idea seems to be a big-ass laser, which isn't likely to be all that efficient.
3) human cargo. The climbers don't move too fast (compared to rockets), and will subject humans inside to a lot of radiation as they go through the Van Allen belts.

Unobtanium? Graphene is already known to exceed the tensile strength required for a space elevator. Get with the program. Nanotubes are 90's tech. Now all we have to do is get mass production methods running,

Nanotubes are indeed 90s tech, but even after all this time no one's figured out how to make them in large quantities. Maybe that's because there's a big lack of funding for research in this area, but the end effect is that, for now, it's still "unobtainium". Same goes for graphene. We're only now exploring how to make microscopic chips with the stuff.

It's sad, because with enough funding and effort, we could probably have one of these launch systems built within 10 years, just like we did with the Apollo program. But humans now just don't have the spirit and drive we did back in the 50s-60s, to do great things, and we'd rather figure out how to preserve tax breaks for the wealthy so they can buy bigger yachts.

Re:Please Mod Parent Up

[Grishnakh]

There's other problems with the space elevator:
1) dealing with all the debris, micrometeorites, etc. it's likely to encounter along its 60,000 mile long path.
2) powering the climbers efficiently.
3) getting humans out into space without killing them with too much radiation. The climbers travel too slowly through the Van Allen belts.

Re:Please Mod Parent Up

[tehcyder]

(The current tallest Ferris wheel in the world is only about 0.1 miles high.)

You have an odd definition of the word "only".

Re:Please Mod Parent Up

[tmosley]

Take a physics class, kid. You've got centripetal and centrifugal mixed up. You ever swung a cat around by the tail? What happens if you let go? Does it fall down, or go flying? The force that sends it flying (the moment of rotation) is what will cause the ribbon to rise. The ribbon stretches such that it's center of mass is beyond geostationary, so the net force is "up". If you can't understand this, then you have no place in this conversation. Go educate yourself with some basic physics, then hit us back.

As to your "understanding" (ie ignorance) of the ribbon:

1. A graphene ribbon can't be damaged. It has the highest deformation modulus of any known material. This is basically stretchy diamond. You have to use a catalyst to cut the stuff.

2. You don't need power for the climbers under my scheme. Having the climbers climb is just a stupid idea--period.

3. Mechanical climbers can't move very fast, but the climber in my scheme can move as fast as you can unroll it.

Yes, you can't make very long nanotubes, but AS I POINTED OUT IN MY POST, there now exist methods to make graphene is sheets as long as you like. All you need is a catalyst on a large roller, a big oven, and a source of argon gas. BFD.

As I said above, graphene has rendered ALL of the questions about space elevators moot, and turned it into a PURELY materials science problem. But the community seems to be stuck in the 90's. It's just stupid.

Re:Please Mod Parent Up

[Rei]

1) SWNTs *are* graphene -- just merely rolled up. Graphene has the same theoretical (~130GPa) -- and likely maximum practical (half that) -- tensile strength as SWNTs.
2) A bulk material will generally have properties way less than that of your strongest individual micro-element. For example, the strongest nanotube composites yet made barely compete with conventional high-strength plastics.
3) "All we have to do is..."? Was that a joke?
4) The below post.

Re:Please Mod Parent Up

[Rei]

1) Graphene absolutely can be damaged; any material can. How do you think diamonds are split by steel tools? You're confusing *abrasion resistance* with *damage immunity*. Micrometeorites pack a large amount of energy in a tiny amount of area -- WAY more than the SP2 bond energies in the graphene bond structure. A micrometeorite impact turns what it strikes into plasma.
2) Your concept simply doesn't work because you have to be able to get your elevator back down. And to do so would require tethering it to Earth with a second space elevator even larger than the first. The net result is that you more than double your tensile strength requirements, which are already preposterously high.
3) Growing a single sheet of graphene is a neat lab trick. It's meaningless, though, because we're talking about *bulk* material. Producing objects that are an atom thick in a serial manner is beyond pointless when your goal is mass production. And FYI, "Ahn and colleagues showed that their graphene-based touch screen could handle twice as much strain as conventional ITO-based devices.". Yeah, what a supermaterial -- a whopping two times as strong as ITO. :P

Re:Please Mod Parent Up

[Rei]

The very design calls for absolutely no unobtanium -- that's the whole point. It's not supported by tensile strength, but by kinetic energy. The only structures in tensile strain are the support ropes to stop it from toppling over to either side; since they only need to go ~80km (instead of over 42,000 km), they can be made of kevlar or similar, rather than unobtanium.

As for "prices for space elevators", give me a break. You've got a price for unobtanium already?

Since you seem to have trouble picturing the concept of a structure supported by kinetic energy, picture this thought exercise. You have an ultralight plate in the air that's using a gyro system to keep itself level. You're lying beneath it holding a basketball. It's going to fall on top of you, right? So you throw the basketball up at it. It hits the plate, transferring kinetic energy to the plate, knocking it back up in the air, and correspondingly accelerating the basketball back down at you. You catch it. The plate stops rising and starts falling. You throw the basketball up at the plate again and repeat the process. The plate is approximately hovering in place.

Now, each time, you're having to throw the basketball. But what if you had an automatic "ball catch and return" system -- a curved loop that takes the incoming basketball and redirects it back upwards, turning its downward momentum back into upward momentum? If all elements of the system were lossless -- the redirection, no air resistance, all energy transferred to the plate losslessly -- the plate would jerkily "hover" indefinitely. And if instead of a single basketball, you had a multitude of tiny particles carrying that kinetic energy in a continuous stream, the plate wouldn't jerk around; it would simply hover. One can easily see that in the absense of losses that the system would require no energy by looking at the gravitational potential energy for the system. It remains the same under suspension.

In a nutshell, that is how kinetically-suspended structures work. The energy that you have to continually "pay" into the system is merely the losses. In the case of the launch loop, your "stream of particles" is a loop of iron turning at high speed. The "redirection" is magnetic. It spins within a near vacuum sheath.

Re:Please Mod Parent Up

[Rei]

Indeed. There's one company out there trying to raise money to build a suborbital variant of a launch loop for launching people on SS1-style joyrides; it'd cost a small fraction of the price of an orbital loop.

Re:Please Mod Parent Up

[Rei]

There's no reason you can't land on a Launch Loop. And the most popular space elevator design out there, Edwards', doesn't allow for atmospheric reentry of climbers.

Re:Please Mod Parent Up

[Rei]

I don't know -- I think once people grasp what a launch loop is all about, they generally find it pretty darn inspiring, too. A space elevator might be an elevator to heaven, but a launch loop is a stairway to heaven (er... escalator? ;) ). There are all sorts of crazy things you can do with kinetically-suspended structures once you think about it. Like, say, having a huge building suspended in the stratosphere on a relatively tiny, guyed pillar, or any sort of arc. No need for a single straight cable all the way past GEO; it's free-form.

Re:Please Mod Parent Up

[Darfeld]

You still need re-entry atmosphere to land on the launch loop. 80km doesn't get you into space. You obviously also need to adjust speed in a non zero G environment. And you'll have to make the loop stronger to handle landing.

And for the climbers of the space elevator, I don't see a problem with re-entry. Their speed would be controlled and slow, so their shouldn't be any burning.

But It's just my understanding of physics. Enlighten me if I'm wrong.

Substantial Progress being made

[mbone]

One of the interesting things about this conference (which I attended) is that nanoscience researchers on Friday reported substantial improvements in the ability to make carbon nanotubes. They can now "grow" 1 cm nanotube mats, which can be spun into fibers. This is a substantial improvement from even 1 year ago.

I still think that a terrestrial space elevator is a decade out, but this year has convinced me that it is coming much faster than a lot of people think.

Re:Substantial Progress being made

[AGMW]

I still think that a terrestrial space elevator is a decade out, but this year has convinced me that it is coming much faster than a lot of people think.

If we actually return to the moon, might a space elevator be more practical there? Could we do that now?
What about Mars ... how close are we to using a SE there?

Re:Substantial Progress being made

[Anonymous Coward]

A decade!?! You are in for some serious disappointment.

Re:Substantial Progress being made

[vlm]

If we actually return to the moon, might a space elevator be more practical there? Could we do that now?

There's a whole wikipedia article on the topic, but in summary, a lunar elevator would be off the shelf. Not off the shelf at your local home depot, but more like Aircraft Spruce and Specialty. Not kidding, I checked their website and they sell kevlar49 spools at about ten cents per foot for 7100 denier.

It would be fun to try on a "smaller" asteroid. Then literally hardware store products would be good enough plus the operational training would be priceless.

Re:Substantial Progress being made

[maxwell demon]

I still think that a terrestrial space elevator is a decade out, but this year has convinced me that it is coming much faster than a lot of people think.

If we actually return to the moon, might a space elevator be more practical there? Could we do that now?

https://secure.wikimedia.org/wikipedia/en/wiki/Lunar_space_elevator

Re:Substantial Progress being made

[Anonymous Coward]

The problem with mars are the moons: they get into the elevator's path. So we should have a mobile space elevator, in order to... dodge moons.

Re:Substantial Progress being made

[mbone]

For Mars, it would probably make more sense to anchor the elevator on Phobos, and live with a 500 m/sec velocity of the tip relative to the surface.

Such a Martian Space Elevator, with Phobos as the counterweight, would be possible with current materials.

Re:Substantial Progress being made

[globaljustin]

>> "It would be fun to try on a "smaller" asteroid"

Agree_asteroids are good training for the next step IMHO

Re:Substantial Progress being made

[renoX]

> nanoscience researchers on Friday reported substantial improvements in the ability to make carbon nanotubes. They can now "grow" 1 cm nanotube mats, which can be spun into fibers. This is a substantial improvement from even 1 year ago.

OK, but what is the strength of those fibers compared to what we need for a space elevator?
I bet that those fibers are not strong enough: until they are (which may never happen), space elevators will remain a dream..

Music

[k31bang]

Like what kind of music to play on the way up?

Re:Music

[Anonymous Coward]

Or what happens when some kid presses the buttons for floors 150-975 then gets off on the second floor?

Re:Music

[buback]

Stairway to Heaven, over and over and over again.

Re:A virus!?

[Anonymous Coward]

Unfortunately not but it's nice that a scam alert site comes up first.

Re:A virus!?

[Dutchmang]

...runs off to check out this excellent offer.

No Elevator for 150 years ?!?

[Dopeskills]

From the article: He was reluctant to guess when a space elevator could actually begin to be built. "We try not to be narrow-minded and say it won't happen for 150 years. Breakthroughs in technology innovation occur on a daily basis," he said.

Who's going to pay

[macraig]

Since it will be shared infrastructure like our roads, the public should retain ownership rather than some for-profit corporation, and the contractors we hire to build it should be thus paid with a tax or bond. Of course the same should have been done with telecom infrastructure (and then we'd have true neutrality of the wires).

Re:Who's going to pay

[macraig]

... and queue the Libertarian rant in 5... 4... 3... 2....

Re:Who's going to pay

[vux984]

I agree. But in the real world even crucial regular bridges are being built by for-profit corporations ... for profit.

Re:Who's going to pay

[macraig]

That's what happens when there's no Eisenhower figure to step up and generate consensus. Yeah, people thought Obama was gonna be that type of figure, but it's not happening. (Eisenhower was a Republican, though perhaps Republicans were less cartoonish back then and acknowledged that taxes and "socialization" were practical for some things.)

Re:Who's going to pay

[0123456]

Eisenhower was a Republican, though perhaps Republicans were less cartoonish back then and acknowledged that taxes and "socialization" were practical for some things.

No, they just hadn't seen clear proof back then of what a disaster socialist policies always are in the long term.

Re:Who's going to pay

[meglon]

Tell that to China, who's currently kicking our asses. Eisenhower actually knew what socialism was as well, instead of just using the word for anything he disagreed with, unlike the current crop of fucking fascist conservatives.

Re:Who's going to pay

[Anonymous Coward]

Yeah, that's why all the Scandinavian countries are in such bad shape...

Re:Who's going to pay

[Mindcontrolled]

Yeah, sure. Them there socialists are out to get you. Be afraid, good citizen, be afraid, there's them there socialist boogeymen in your closet! I just stay in my European socialist hellhole and enjoy life. The US were on the road to third-world status when I worked there in the early 2000s - go ahead and slide further in to your banana republic mode, you seem to enjoy it. I just pity the decent guys over there. But hey, if you want to get out - i got two large sofas in the living room - ample space for a couple of refugees.

Re:Who's going to pay

[kurthr]

Dude-

Appreciate the sentiment, but careful what you offer... someone will take you up on it :P

Re:Who's going to pay

[macraig]

I would myself, but he said nothing about allowing cats to tag along.

Re:Who's going to pay

[sgt scrub]

All of the AAA countries have a socialist party. Socialism is to Capitalism what a Republic is to a Democracy, balance. If our founding fathers would have placed that balance into the constitution we would be in a much better place.

Re:Who's going to pay

[Mindcontrolled]

Cats are fine. Fridge is stuffed with Bavarian beer. The Mindcontrolled Refugee Center is open for business ;)

Re:Who's going to pay

[macraig]

Awesome! I'll be packing and text you.

Re:Who's going to pay

[Anonymous Coward]

"cue". The word you are looking for is "cue". The metaphor you are employing is that of a play or concert, with you as the director or conductor. You believe it is time for a "Libertarian rant", so you give the "cue".

Re:Who's going to pay

[macraig]

Agreed. I'm not sure why I picked the synonym when both are in my vocabulary.

Re:Who's going to pay

[cusco]

Homonym

Re:Who's going to pay

[macraig]

Ouch! I need to triple the dosage....

Re:A virus!?

[Anonymous Coward]

A few years ago I installed linux. Then there were no more viruses. If you are having computer problems, I wholeheartedly recommend something better than windows.

Re:Delusional mental patients

[Lanteran]

Did you miss the last few decades there, buddy?

Re:A virus!?

[Anonymous Coward]

A few years ago I contracted a virus called linux. It gave me Open Sores.

FYP

We should use our old rockets first

[iamacat]

Our lack of progress in space exploration has more to do with losing the will than limitations of technology. We could have launched a mission to Alpha Centauri by now if we pursued project Orion with modern advances to material science and optimized computer control of propulsion. If we are not doing that, who is to say we will build a space elevator even if the technology is feasible?

Re:We should use our old rockets first

[Ambvai]

Which reminds me of a story I came across once-- it was basically the journal of an explorer who left Earth to some distant system with the intent to beam information back and start the colonization of the universe. Turns out, when he [and the rest of the crew] got there, space travel had advanced so much that he was welcomed as an artifact that only historians cared about while his trip amounted to nothing more than a footnote in the history books. (Plus a little extra human interest about his wife and kids being one of the first colonists on the planet and having long since died.)

Re:We should use our old rockets first

[Arlet]

We could have launched a mission to Alpha Centauri by now if we pursued project Orion

I don't think the plans for project Orion involved slowing down at the destination, so it would be a rather pointless exercise of zipping through the Alpha Centauri system at 0.03 c, and hopefully taking a few blurry pictures of a planet before entering interstellar space again.

Re:We should use our old rockets first

[Zontar The Mindless]

Sounds to me like the problem's with the plan, then, and not with iamacat's comment.

Re:We should use our old rockets first

[loufoque]

The reason we're not doing is that nuclear scares people.
Nuclear power plants are being closed and replaced by burning more oil as we speak.

Re:We should use our old rockets first

[Arlet]

Both. We don't have the will to proceed with silly plans, and we lack the technology for a better plan.

Re:We should use our old rockets first

[Anonymous Coward]

Seems to me the wiser choice is to learn how to thrive in space, first. Once we are able sustain a space-bourne existence, we can just migrate to a new star system within our known limitations of physics. For instance, build a space station large enough to sustain, I dunno, maybe a thousand souls, and then spend multiple generations, at sub light speed, getting to Alpha Centauri.
I mean, I agree that exploration to another star system is a worthy endeavour, but I feel our primary focus should be getting out of our gravity well permanently, first. Exploration is a natural evolution once we are out there.

Re:We should use our old rockets first

[cusco]

It distresses me that we (the US) don't even have the technology to put a man in LEO today, we have to rent the capability from Russia or China.

Chemical bond strength vs Gravitational strength

[John.P.Jones]

I was thinking about how the energy of chemical rockets is just barely sufficient (given fuel mass) to make chemical rockets that can escape Earth's gravity well. I'm not sure of the exact headroom but my understanding is that it is fairly tight. From what I have read on the strength of nanotubes, they too are theoretically just strong enough to barely make a space elevator a possibility (if we could manage to weave them into a macro-fiber without significant losses.) If this turns out to be the case I wonder if there is a connection between these two methods and the strength of chemical bonds to overcome the gravitational potential of our planet. Need it be so that these two very different ways of utilizing bond strength achieve a similar maximum gravitational field that they can overcome? And even more speculatively could the fact that the gravitational field of the Earth is near this value be important in the suitability of it to life?

Re:A virus!?

[nmb3000]

Unfortunately not but it's nice that a scam alert site comes up first.

Google indexes Slashdot comments, but will not pay any attention to links they contain. All URLs inside comments include the rel="nofollow" attribute, excluding them from participating in search engine ranking.

Re:Chemical bond strength vs Gravitational strengt

[Anonymous Coward]

Hexapodia the key insight?

I like Launch Loops myself.

[Soralin]

http://en.wikipedia.org/wiki/Launch_loop Launch loops are basically a big cable, supported magnetically in a vacuum sheath, and accelerated up to high speeds (14km/s+), it could be set up as a 2000km long track along the ground, about 80km up. Since it's moving faster than escape velocity, it would appear to move away from the ground, since the ground is curving away from it faster than it's moving. so it would just need to be tethered to put it into a nice flat path, and could be magnetically looped around and sent back the other way at the end stations. A craft to be launched could just produce a magnetic field, and it would be pulled along at 3g or so, and could let go when it got up to it's desired speed, with a small rocket to circularize it's orbit at higher than 80km, if it's not headed off at escape velocity.

It solves a number of issues that are problems for a space elevator, like how to get something to climb up a tether, or get power to it, which can be done relatively easily for a launch loop, since it could just pull power off the grid whenever it's convenient, and store it in the motion of the cable itself. And it doesn't need any new materials, or really strong ones or anything like that. Not to mention, being much faster to get to orbit, but still suitable for acceleration-sensitive cargo, such as humans. And it can launch quite a bit more material/time then a space elevator can, at a cheaper price. Mainly limited just by the amount of electrical power it has available, and at high power levels, by the need for the cable to cool down between launches.

Only major downside would be that it isn't statically stable, there would have to be dynamic control of the rotor at the end stations, given that it's all just supported and directed magnetically. And it would need to remain powered to keep it from eventually collapsing.

Will the Door Close button work?

[kawabago]

It would be a nice to have at least one elevator on the planet where that button worked.

Too Slow.

[Colin Smith]

"But the delta-v required would become as low as we please, making very cheap and low-power sources effective"

By that you mean slow => With very poor throughput.

Poor throughput means not economically viable. Which means yet another boondogle which your average spud is going to have to pay for.

Re:Too Slow.

[svick]

That just means the time to get to orbit would be slower compared to the shuttle or conventional rockets.

But the actual throughput will be much higher, because you don't need to wait several months between launches.

Re:Chemical bond strength vs Gravitational strengt

[UCSCTek]

That's quite the stretch.

Naively, I would say the important comparison is between the scale of thermal energy available on Earth to organic bond strengths. I don't see gravity being a large issue.

Re:A virus!?

[Anonymous Coward]

N.B This troll posting has been moderated up courtesy of your friendly representative from Redmond.

“Mopping Up can be a lot of fun. In the Mopping Up phase, Evangelism’s goal is to put the final nail into the competing technology’s coffin, and bury it in the burning depths of the earth. Ideally, use of the competing technology becomes associated with mental deficiency, as in, “he believes in Santa Claus, the Easter Bunny, and Linux.” Just keep rubbing it in, via the press, analysts, newsgroups, whatever. Make the complete failure of the competition’s technology part of the mythology of the computer industry.”

–James Plamondon, Microsoft

Re:Chemical bond strength vs Gravitational strengt

[Anonymous Coward]

Interesting point. Carbon-carbon bond energy is indeed pivotal to both methods.

why not build a launch loop?

[Anonymous Coward]

http://en.wikipedia.org/wiki/Launch_loop

Re:A virus!?

[Anonymous Coward]

Would be true except nobody cares about Linux on the desktop. People spend a fortune buying macs 'cause they can't stand Windows yet would rather pull teeth out than run Linux.

Is free as in speech really worth something if the speech only sometimes comes out and when it does can barely be understood? That's Linux free speech for you: free as in laryngitis.

list of countries by nominal GDP per capita

[Anonymous Coward]

1 Luxembourg (socialist) 108,832
2 Norway (socialist) 84,444
3 Qatar (oil money) 76,168
4 Switzerland (socialist) 67,246
5 United Arab Emirates (oil money) 59,717
6 Denmark (socialist) 56,147
7 Australia (socialist) 55,590
8 Sweden (socialist) 48,875
9 United States (capitalist) 47,284
10 Netherlands (socialist) 47,172
11 Canada (socialist) 46,215
12 Ireland (socialist) 45,689

not seeing it dude

JSEA

[mattr]

The Japan Space Elevator Association (http://www.jsea.jp in Japanese) in addition to covering technical and engineering also considers business and legal issues. And here is a video from JSETEC 2011 shot in Fujinomiya City, Shizuoka Prefecture on August 7 showing a climber built by Takane Matsumoto of Team Aquarius. Certainly it's cool that something like his climber exists! I don't know how high it went but I think they were going for 600m altitude. Anyway I expect these groups would welcome anybody who wanted to investigate building a loop instead.

The major nitpick

[dbIII]

Space elevators would make space travel much cheaper. But the technical issues are immense.

We can't honestly say the first part without having a bit more of a clue about the second.

Re:The major nitpick

[Surt]

That may not be the case. We have a clue about the technical issues, and there isn't really reason to believe they'd raise the launch costs by more than 10x, at which point it would still cut costs in half.

Re:The major nitpick

[dbIII]

We don't even know what material can be used (carbon nanotubes are not good enough yet and may never be so it could be something else), how much fuel will have to be used for construction and station keeping and so how much needs to be launched by beanstalk (and how it goes up the thing) to reach a break even point in fuel versus rocket launches. We don't know those things within an order of magnitude or two so it's no time to start talking about costs. There's a truckload of unknowns between "might" and "will".
Optimism is a good thing so long as it doesn't pretend to be real. False certainty is ultimately lying and misleading people no matter how noble you think the goal is.

JSEA

[mattr]

OP says nobody is thinking about costs. However the Japan Space Elevator Association (http://www.jsea.jp in Japanese) in addition to covering technical and engineering also considers business and legal issues. Their site says they are the only group to cover legal.
I once attended a meeting of theirs and a manager from a leading aerospace company was in charge. Their website also mentions someone's estimate of about 200M USD to build a megafloater island not counting cost of the station and elevator itself.

FWIW here is a video from JSETEC 2011 shot in Fujinomiya City, Shizuoka Prefecture on August 7 showing a climber built by Takane Matsumoto of Team Aquarius. Certainly it's cool that something like his climber exists! I don't know how high it went but I think they were going for 600m altitude. Anyway I expect these groups would welcome anybody who wanted to investigate building a loop instead. I am not involved with these guys but some of the posts here suggest LAN parties to play the latest first person shooter is of greater value than what these guys are doing, all I can say is that kind of thinking is what leads to the utterly morally bankrupt society and economy that is currently on world display. Hint I am not talking about the country that just got hit by earthquake, tsunami and nuclear disasters. Where's Slashdot's geek cred?

Are they for real with those questions?

[roman_mir]

So the questions are: can you have 6 climbers on a ribbon instead of 3?

Seriously, those are the questions? So I guess they have a ribbon that allows 1 climber already then?

How about REAL questions:

1. What is the maximum carbon fiber ribbon length can you even make with current technologies? What is the longest length of ribbon that can be made that will support its own weight with current tech?

2. What is the climate and weather going to do to the ribbon? Rain? Thunderstorm? Tornado? Hail? Even all the Sun light? A meteor strike? Lightning? Static electricity?

3. Can you pull the ribbon into space in case something serious is taking place near the planet's surface, like a huge storm?

4. What about fire, will this thing burn? What if a fire starts while climber is on its way, half way through?

5. Will there be a way to evacuate from the climber with parachutes or rockets or whatever in case of emergency?

6. How do you make the ribbon stay in one place above the ground anyway?

Can they can answer those questions above before talking about having simultaneous 6 climbers instead of 3? Because they have to answer those questions before they can even do 1.

Re:Are they for real with those questions?

[mbone]

1. What is the maximum carbon fiber ribbon length can you even make with current technologies? What is the longest length of ribbon that can be made that will support its own weight with current tech?

About an inch right now, but it can be spun. No one thinks that the SE will have 100,000 long nanotubes - they will be centimeters long. Each bond is fairly weak, but the # of bonds increase with length and so short tubes can be bonded together. The real question is, how long do the fibers have to be to have a really solid bond. Longer than 1 inch, but no one knows how much more. It's unlikely to be more than a factor of 10, though.

2. What is the climate and weather going to do to the ribbon? Rain? Thunderstorm? Tornado? Hail? Even all the Sun light? A meteor strike? Lightning? Static electricity?

The big worries (to me) are meteors, space debris and radioactivity. Radioactivity may force the use of boron nitride nanotubes, which would set
things back by decade probably.

3. Can you pull the ribbon into space in case something serious is taking place near the planet's surface, like a huge storm?

Yes. Easy to do at the counterweight at the far end. Would take some hours for the wave to move down and the Earth end raise up, but it is the obvious "Plan B" for a dire emergency on the ground.

4. What about fire, will this thing burn? What if a fire starts while climber is on its way, half way through?

Not in space. The last 20 km of the cable are likely to be rather different (shielded, etc.), to avoid such atmospheric problems.

5. Will there be a way to evacuate from the climber with parachutes or rockets or whatever in case of emergency?

If you are 10 km up, sure, parachute back. If you are 30,000 km up, also sure. (Detach from the cable and you're in orbit.)

There is a zone in between where bailing out will not be so good. Multiple cables will probably be necessary before this becomes a mass-market vacation option.

6. How do you make the ribbon stay in one place above the ground anyway?

It's in orbit once per day, so to "first order" it stays put. Now, it will want to move about, at the 100 meter to 1 km level, because of tides and the like. If you anchor the terrestrial end, that thus means you are imposing waves on the cable. That seems to be OK, but more work is definitely needed here IMO.

Can they can answer those questions above before talking about having simultaneous 6 climbers instead of 3? Because they have to answer those questions before they can even do 1.

But that is misleading. There are answers to all of those things (maybe imperfect). You still need to think about things like shipping throughput if you are going to sell it and get it built,, even while you are working though all of the other issues.

Re:Are they for real with those questions?

[LBU.Zorro]

3. Can you pull the ribbon into space in case something serious is taking place near the planet's surface, like a huge storm?

Yes. Easy to do at the counterweight at the far end. Would take some hours for the wave to move down and the Earth end raise up, but it is the obvious "Plan B" for a dire emergency on the ground.

What? Seriously you think you can just detach the ribbon from the base station and then attach it again? If the ribbon breaks at the base (the same scenario as detaching it) then the ribbon is lost to space.

The ribbon has to be under tension at the base, as in attempting to lift the base off the ground in order for anything to be able to climb it, otherwise you're attempting to climb an unsupported ribbon, which means the ribbon wants to escape but the base station doesn't let it. If there wasn't any tension in the base of the ribbon, you'd be climbing the inertia of the ribbon only, which means after all that effort, you can launch one item (and even then you need to climb quickly).

This isn't something you can just pull in and out or have hover about, the entire edifice is in dynamic tension and losing one of those balanced forces will bring the entire thing down (or up, or off or whatever).

6. How do you make the ribbon stay in one place above the ground anyway?

It's in orbit once per day, so to "first order" it stays put. Now, it will want to move about, at the 100 meter to 1 km level, because of tides and the like. If you anchor the terrestrial end, that thus means you are imposing waves on the cable. That seems to be OK, but more work is definitely needed here IMO.

It's anchored to a floating platform in the sea (not seen any viable discussions of land based elevators), the ribbon isn't like a rope dangling in the sky that you climb, it's not a rope ladder. The terrestrial end HAS to be anchored to a counter-weight that can also be supported by the earth in order to have tension you can exploit to climb the cable.

Z.

What's the point?

[Anonymous Coward]

The technical difficulties of building a space elevator make an interesting puzzle, but unless I've missed a major revelation, there still isn't anywhere that people really need to go in space, and certainly no mechanism for making journeys bearably fast. Not even in theory.

Wouldn't it be better for everyone if $18billion was spent on renewable energy research? Or social care. Or, well, almost anything else?

Re:What's the point?

[LBU.Zorro]

Well if you think it through the most effective renewable energy is space based solar, it's much more dense, permanently on and doesn't annoy anyone.

This starts being really possible with a space elevator, both for getting the machinery into space in the first place and getting the power back down (there's been talk of conductive cores to the elevators).

Is it really better for everyone if another $18billion is spent on social care? Isn't that just stopgap spending, spend a little more to temporarily make people feel better without actually changing anything? No new resources, no new energy sources etc? According to a quick look at http://en.wikipedia.org/wiki/2008_United_States_federal_budget it seems that about $1.527 trillion was spent on welfare, how would $18 billion (1.1%) even be noticed in a budget of that size? Or add to it more than cheap and reliable access to space would? How about power costs dropping to fractions of what they are today? How about the reductions in pollution from shutting down fossil fuel power plants? How about dealing with nuclear waste once and for all? How about a reduction in wars and exploitation because the need for oil has just dropped massively?

The benefits of a space elevator out weigh pretty much anything you could possibly think of to do with $18 billion, spending it on anything else is short-sighted and really not going to change anything except probably make it worse.

Z.

This is way harder than you think...

[Genda]

This is not just putting a cable in orbit. Consider a long list of stability problems inherent to any project of this type. Everything from Harmonic vibration, to Coriolis effect, to shear from solar winds and complex interactions with the ionosphere. It might take a month to lift a cable car safely. Okay for raw materials, not so great for people or perishables.

Also imagine you have a 45,000 mile long antenna that extends out into the solar wind. Can you imagine the kind of voltages and currents that this thing will induce? The mind boggles.At its base you would need huge superconductors to draw charge off the cable to allow it to function at all. Of course there would be the up side in that it would generate enough power to operate itself and a fair part of the country the base was located in, It would just be an incredibly expensive and challenging endeavor.

None if this is to say we shouldn't pursue this end, it would transform what was possible for humanity. Just don't have illusions to how difficult, or complicated this undertaking would be. It would demand our best and brightest working for decades.

Re:This is way harder than you think...

[Palpatine_li]

Obviously you haven't read any of the reports. There is at least one as linked by JoshuaZ, a report for a NASA grant for preliminary study, and one by the japan association of space elevator. They have considered more problems with SE than you can think of. Though their prediction of the material development was a bit too optimistic.

Re:A virus!?

[Anonymous Coward]

Does this work?

I'll just copy/paste this here...

[denzacar]

https://secure.wikimedia.org/wikipedia/en/wiki/Launch_loop#Difficulties_of_launch_loops

Difficulties of launch loops

A running loop would have an extremely large amount of energy in the form of linear momentum. While the magnetic suspension system would be highly redundant, with failures of small sections having essentially no effect at all, if a major failure did occur the energy in the loop (1.5Ã--1015 joules or 1.5 petajoules) would be approaching the same total energy release as a nuclear bomb explosion (350 kilotons of TNT equivalent), although not emitting nuclear radiation.

While this is a large amount of energy, it is unlikely that this would destroy very much of the structure due to its very large size, and because most of the energy would be deliberately dumped at preselected places when the failure is detected. Steps might need to be taken to lower the cable down from 80 km altitude with minimal damage, such as parachutes.

Therefore for safety and astrodynamic reasons, launch loops are intended to be installed over an ocean near the equator, well away from habitation.

The published design of a launch loop requires electronic control of the magnetic levitation to minimise power dissipation and to stabilise the otherwise under-damped cable.

The two main points of instability are the turnaround sections and the cable.

The turnaround sections are potentially unstable, since movement of the rotor away from the magnets gives reduced magnetic attraction, whereas movements closer gives increased attraction. In either case, instability occurs.[3] This problem is routinely solved with existing servo control systems that vary the strength of the magnets. Although servo reliability is a potential issue, at the high speed of the rotor, very many consecutive sections would need to fail for the rotor containment to be lost.[3]

The cable sections also share this potential issue, although the forces are much lower.[3] However, an additional instability is present in that the cable/sheath/rotor may undergo meandering modes (similar to a Lariat chain) that grow in amplitude without limit. Lofstrom believes that this instability also can be controlled in real time by servo mechanisms, although this has never been attempted.
[edit] Competing and similar designs

In works by Alexander Bolonkin [7][8][9] it is suggested that Lofstrom's project has many non-solved problems and that it is very far from a current technology. For example, the Lofstrom project has expansion joints between 1.5 meter iron plates. Their speeds (under gravitation, friction) can be different and Bolonkin claims that they could wedge in the tube;[citation needed] and the force and friction in the ground 28 km diameter turnaround sections are gigantic. In 2008[10], Bolonkin proposed a simple rotated close-loop cable to launch the space apparatus in a way suitable for current technology.

Another project, the space cable, is a smaller design by John Knapman that is intended for launch assist for conventional rockets and suborbital tourism. The space cable design uses electrodynamic levitation rather than electromagnetic levitation and discrete bolts rather than a continuous rotor, as with the launch loop architecture. John Knapman has also mathematically shown that the meander instability can be tamed.[11]

For extra credit:

- Come up with necessary security measures for a 2000 kilometers long and 80 kilometers high structure which doubles as a rail-gun and which acts just like an atomic bomb if something goes wrong.
- Practice saying "But there would be no radiation even if it DID explode" in front of a mirror.
- Come up with a reason why is it somehow NOT impossible to build 80 kilometers long anchor cables, but stacking those cables as sections of a much longer cable IS.
- Invent a perpetual motion machine which would both power the 2000 kilometer long structure keeping it "aloft" AND provide additional energy needed to launch the payload.

Re:I'll just copy/paste this here...

[Grishnakh]

- Come up with necessary security measures for a 2000 kilometers long and 80 kilometers high structure which doubles as a rail-gun and which acts just like an atomic bomb if something goes wrong.

No big deal. The only parts that are near land are right at the very ends; the majority of the loop is 80km up in the air. How are terrorists going to get to that? All you need is a few ground defenses with AAA at the ends, and maybe some jets around that are ready to scramble. 80km is too high for anything other than other spacecraft/rockets to get to, so there's no worry there except from countries that have rockets capable of reaching that, which isn't many.

- Practice saying "But there would be no radiation even if it DID explode" in front of a mirror.

So what? You're acting like a nuclear bomb is world-shattering or something. It's not, it's really no big deal, except of course for the radiation, which this thing doesn't have. Dozens and dozens of nuclear bombs have been exploded on the planet over the past half-century or so; have they affected you in any significant way (assuming you don't live near any of the blast sites)? No. Chernobyl, which wasn't a bomb at all, probably affected far, far more people than all the nuclear bomb tests in history (except of course Hiroshima and Nagasaki, but those weren't tests and to be pedantic, they weren't even [thermo]nuclear, they were atomic).

Now obviously, a blast that large would suck to be close to, but presumably this thing would be located away from any large populations of humans. If a radiation-free nuclear bomb the size of Tsar Bomba exploded in the middle of the Pacific, far from any land or ships, would anyone notice?

- Invent a perpetual motion machine which would both power the 2000 kilometer long structure keeping it "aloft" AND provide additional energy needed to launch the payload.

Maybe I'm missing something, but in my small amount of reading on the subject, I never saw anyone suggest the thing would be powered for free. In fact, I believe I read that it's not even economical unless it's used regularly, which would make sense because if you're going to just make one launch a year, it would be cheaper to just build a rocket and use conventional rocket fuel; this thing needs continuous power, so it only makes sense if you're launching a lot of stuff, perhaps one launch a day, or even every 5 minutes. The more you launch, the more economical it is.

The idea of the thing, as I understand it, is that it's a giant energy-storage device. So you put enough energy into it to get it up to speed and maintain that speed, and it stores that energy. Then, when you launch things, the additional energy needed for each launch is very small, compared to what you'd need to launch a rocket with that payload.

- Come up with a reason why is it somehow NOT impossible to build 80 kilometers long anchor cables, but stacking those cables as sections of a much longer cable IS.

80km long cables are nothing special; there's undersea cables that are much, much longer than that already and have been for decades. 80km long structural cables aren't anything special either, just longer versions of what we already make. The key is the tensile strength needed for such cables. The problem with the space elevator is that it needs an enormous amount of tensile strength in the cable, more than any currently-made material, though a carbon nanotube composite is likely to be sufficient. The anchor cables for the launch loop probably don't need anywhere near that much strength, and can be made from conventional materials.

Re:I'll just copy/paste this here...

[denzacar]

No big deal. The only parts that are near land are right at the very ends; the majority of the loop is 80km up in the air. How are terrorists going to get to that? ll you need is a few ground defenses with AAA at the ends, and maybe some jets around that are ready to scramble.

LOL!

They don't need to get to the part that's 80 km up in the air.
Anything from crashing a plane anywhere into the structure (and this time, we're talking a Cessna not a Boeing) to causing an overload in the powerplant supplying the structure will cause it to crash.
Only when it crashes it will be like an A-Bomb, wiping out things for miles around.

Oh and... "ground defenses with AAA... and maybe some jets"? You remember perhaps how that plane crashed into Pentagon?
You know... One of the biggest military installations in the world. They didn't have that kind of support.
"Some jets" cost a LOT to fly and maintain. Bonus points for such toys being under military control AND command.
It takes a shitload of authorizations to just take those planes up in the air, let alone to have them fire off a round.

Near an installation particularly susceptible to gunfire, might I add.

And should it be built so that it float in the ocean, there's a whole series of other safety issues not solvable by "some jets" - like storms and hurricanes.
Heck... just the fact that it would be a biggest electromagnet in the world and a biggest LIGHTNING-ROD in the world would be a fun thing to observe, come first clouds.

Also, most of the structure being "up in the air", we are not talking about protecting a ground area, but of a 3D area extending for kilometers up and out around the structure's anchor points.
And those go along the entire length of the structure. The whole 2000 kilometers of it.

There are not enough "some jets" in the world to guard something like that 24/7/365.

So what? You're acting like a nuclear bomb is world-shattering or something.

So NIMBY.
Not in ANY yard, ANY where. Good luck building that. Particularly with THAT attitude.

The idea of the thing, as I understand it, is that it's a giant energy-storage device.

Try "energy sink" instead.
It takes HUGE amounts of power to get it even operational, once you've got it built despite it being literally THE most dangerous structure in the world (imagine an atomic bomb with a pressure-switch balanced on a pedestal made out of toothpicks), and then it uses up energy continuously just to stay afloat.
Add more if you want something launched from it.

energy needed for each launch is very small, compared to what you'd need to launch a rocket

Except you can STORE the energy that will be used by the rocket until you need it.
You can't store electricity you don't plan to (or that you can't) spend at the moment. Not without significant waste.
And significant safety issues.

Basically, you'd have to go nuclear with that thing IF you want to absolutely, positively keep it up in the air.
So now, when it goes boom - it is also radioactive.
With an added bonus that you could have a meltdown first and THEN "the boom".

80km long cables are nothing special; there's undersea cables that are much...
The anchor cables for the launch loop probably don't need anywhere near that much strength, and can be made from conventional materials.

Undersea cables are LAID OUT on the ocean floor.
PLUS, they are not holding anything in place.

These babies would have to go straight up in the air, in order to anchor the 2000 kilometer long structure to the ground.

That's the same unobtainium used in the production of the space elevator.

Re:I'll just copy/paste this here...

[Rei]

Wrong on every count.

1) A space elevator stores the energy equivalent of a small to medium-sized atomic weapon. But ignoring that it's out at sea (where we've done tons of atomic testing, and nobody who's not likewise out there notices), it's a large amount of energy spread out over a large area (largely way off the ground, at that). 2000km, 350kt = under 200kg of TNT equivalent per meter. That's more like a large strip-mining detonation than anything else. FYI: Space elevators, too, store a large amount of energy (gravitational potential instead of kinetic), but they likewise would lose it over a large area high up in the event of a failure.

2) "Built out in the ocean" -- Launch Loops are proposed to be situated in the same spot as Space Elevators (since the storm threats apply to both -- although they're much more harmful to a space elevator, due to how small of a safety margin you can afford even with preposterous-strength materials used). That spot is on the equator, west of the Galapagos, in a region with no hurricanes and little storm activity. In the case of a launch loop, the entire structure is a lightning rod (a big iron loop), and the amount of energy lightning would add to the system in terms of heat to dissipate is insignificant compared to the thermal mass of the system. It's already been well studied.

3) Launch loops do not "use huge amounts of energy to stay afloat". Once it has been spun up, you only have to pay for *losses*. Remember, E=mgh. If m is constant, g is constant, and h is constant, your gravitational potential energy is constant too. No delta-E, no energy input required except for losses. And, the whole design is about minimizing said losses (hence the vacuum sheath, magnetic deflectors, etc). The energy for launches dwarfs the energy for maintenance with any reasonable launch rate.

4) Can't store energy? Launch loops are a giant energy store. How could you forget that? You were just talking about how they store as much energy as an atomic bomb, and now suddenly in your view they don't store any energy? You have to pump in energy for weeks to months to get the thing spun up.

5) No. An 80km cable does NOT have the same tensile requirements as a 42,000+ km cable. The reason space elevators have to be made of unobtanium is that it takes unobtanium *and* a highly tapered cable to be able to merely hold its own weight when it's 42,000+ km long. At 80km, you can make it out of plain old kevlar. It doesn't matter how many 80km cables you have -- the material requirements don't change just because you need more of them.

Re:I'll just copy/paste this here...

[Rei]

Just read your post again and ran into more errors.

They don't need to get to the part that's 80 km up in the air.
Anything from crashing a plane anywhere into the structure (and this time, we're talking a Cessna not a Boeing) to causing an overload in the powerplant supplying the structure will cause it to crash.

Taking out the power plant will *not* cause a structural failure of a launch loop. It causes it to slowly (weeks to months) lose altitude.

Oh and... "ground defenses with AAA... and maybe some jets"? You remember perhaps how that plane crashed into Pentagon?

You mean, in a densely populated civilian area with some of the densest air traffic in the world? Controlling the skies in open water far at sea is WAY easier.

Also, most of the structure being "up in the air", we are not talking about protecting a ground area, but of a 3D area extending for kilometers up and out around the structure's anchor points. And those go along the entire length of the structure. The whole 2000 kilometers of it.

Individual anchor cables can be lost, in the default design, without system failure. One can put in whatever sort of anchoring safety margin they wish; it's not like a space elevator where physics limits you to a tiny error margin.

Re:A virus!?

[Anonymous Coward]

Yes, because this advertisement will totally work on the /. crowd!

Indiana State Fair Stage Collapse

[Anonymous Coward]

Perhaps instead of dreams of outer space, they can fulfill dreams of a stage that is wind proof? How about building a stage and prove this space elevator can do anything at all.

They are looking

[Anonymous Coward]

'It's been nine years we've been looking for someone

Uncle Sam has been proven to be quite talented at looking at someone. Give him the job, as he really needs it!

Build one on the moon first.

[Anonymous Coward]

To work out some of the issues with the system in a gravity that is 1/6 earths gravity and no atmosphere to mess with things. If we can't get it to work there, then we couldn't build one in earth orbit.

Then use this elevator to lower a moon base down onto the moon piece by piece. Launch all the space missions to the rest of the solar system from the moon elevator.

Cheaper Construction Transport

[Anonymous Coward]

One difficulty will be getting the elevator into space before unwinding... I assume that is the method. Chemical rockets are probably not adequate... If we could relax the prohibition to atmospheric atomic explosions for this purpose, Orion atomic rockets could launch the elevator into space and production, and then only be allowed in space. That would really open up space exploration!

Why Space Elevator, when we could use ETT?

[Anonymous Coward]

http://www.youtube.com/watch?v=03kVU2FYl6U&t=463

( For another interesting video on ETT: http://www.youtube.com/watch?v=92dK_yxaKvk )

Re:Chemical bond strength vs Gravitational strengt

[MountainLogic]

Now there is an interesting coefficient to add to the Drake equation. Also, another one would be too much gravity to leave their plant so many fewer hot rods of the gods.

Shudder!

[nanospook]

Won't we have to worry about rats? The high up they live, the larger!

Again with the stupid space elevator ..

[Anonymous Coward]

People need to learn the difference between fiction and fiction based on science. One is just an imagination, while the other is an idea with looks to the future.

The space elevator is FICTION (as currently defined). A dumb idea that has zero based on real science and will never be a reality .... because it is IMPOSSIBLE to achieve. The physics required for the geo-stable space platform alone aren't even near minimum achievable. Anybody who believes the physics are there is completely delusional.

And let not forget about the structural, material and mechanical requirements. They may be (eventually) achievable, but without the geo-stable platform ... it is just a waste of money and resources on the wrong idea. And delusional people always forget about the unpredictability of nature ..... you know ... weather (ie: storms).

Re:Again with the stupid space elevator ..

[LBU.Zorro]

Ahh a troll!

Yes, it is fiction, for it is not (yet) reality - the very definition of fiction.

It doesn't appear to be impossible, just very difficult.

Physics required for a geo-stable space platform? Huh? Do you mean something in geosynchronous orbit? Like say satellite TV? All those satellites are in geosynch orbit so you don't need active dishes to track them - geosynchronous orbit isn't difficult and is done every day.

The materials sciences for the ribbon material? Yes that isn't available yet, but it's on the way. There is no theoretical reason why we cannot build one, only practical reasons as we've not developed the materials yet.

One of the fun things you can do is look at what we have now, look at our scientific understanding of the universe from gravitation to atoms and then keep plugging away and testing and seeing what you get.

The theory describes materials such as carbon nano-tubes or graphene with sufficient tensile strength vs their weight to be able to build a space elevator. We cannot manufacture them in long enough sections yet but they are improving all the time - there's a lot of money in working out how to make this stuff.

Storms are engineering challenges, after all we manage to stick large unsupported free-standing structures up into storms and have them stay up, obviously this means we've got no idea how to do it at all and have just been lucky. Sheesh.

The people who are thinking about this aren't delusional (any more than the average population is - and probably less), these are just problems (even though you find them scary and don't understand) and they can be solved one way or another.

Z.

University of North Dakota

[Dwonis]

Go to UND. I'm not even joking.

Continental Drift

[Anonymous Coward]

Continental drift has been, for me, the obvious spanner in the works. IIUC, a space elevator would have to be situated right on the equator. If built on land, continental drift will bring it out of alignment; if at sea, a simple storm could prove disastrous. Am I wrong here?

Re:Continental Drift

[LBU.Zorro]

Yes.

It's planned to be built at sea, so no continental drift to worry about.

Sea allows mobility (to an extent) to avoid the worst storms (and there are areas that get very few hurricanes) but just building big and strong enough would protect against things like hurricanes.

A quick search of oil rigs (and I'd assume these are smaller than the base station would be) shows that they get hit all the time (and damaged all the time) but the ones that leap out at me were those that had an oil tanker smacked into them. One major advantage of being at sea is that there is very little debris to be flinging at your base station and no continental shelf to raise up waves / tsunamis.

It's just an engineering problem there, nothing fundamentally unsolvable (except perhaps the ribbon, but it's looking good there too).

Z.

Re:A virus!?

[justsayin]

Seriously, this kind of stuff in /.? Is this a joke? Surely no one reading this page is dumb enough to fall for SPAM.

I thought

[Anonymous Coward]

only people who believe in an old guy with white beard up in the sky were nut cases. Let me add them those want to get to him with the Great Indian Rope trick (that is proper India, for my fellow Americans) .

Re:Chemical bond strength vs Gravitational strengt

[Anonymous Coward]

The year after I was born, the British Astronomer Royal's response to Kennedy's promise to put a man on the moon "within [the] decade" was, "We will not see a person on the moon in our lifetime." He was no dumbo, but he didn't have a working knowledge of US engineering at the time. Likewise, pick up any current textbook on the materials needed for a space elevator, and another on the physics of using those materials in such a way, and they probably contain very little practical knowledge on how to actually do this. Meanwhile, engineers are working in government organisations and private corporations to create the frameworks that will begin to make it possible, and the motivation is greater than any Presidential edict, it's greed.