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First Pure Nanotube Fibers Made

timothy posted more than 10 years ago | from the now-make-a-parka-from-them dept.

Science 97

TheSync writes "Researchers at Rice have announced the discovery of how to create continuous fibers from single-wall carbon nanotubes (SWNT). The breakthrough was based on the ability to dissolve a large amount of SWNTs in sulfuric acid, up to 10% SWNTs in solution. At high concentrations, the SWNTs form tightly packed liquid crystals that can be processed into pure fibers. The Space Elevator can't be far away now..."

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Heh (4, Funny)

smoondog (85133) | more than 10 years ago | (#7675335)

The Space Elevator can't be far away now...

Unfortunately, it needs to be on average 35,000 Km away to work.

-Sean

The space elevator is such a joke. (-1, Flamebait)

Anonymous Coward | more than 10 years ago | (#7675539)

What's the largest flaw size they expect it to tolerate? Fatigue resistance? Fretting? Radiation? Corrosion? Wind resistance? Capillary action of water?

While we're at it what's the yield stress of wishful thinking?

Nanotubes are great for many reasons. But a space elevator isn't one of them. They might as well pimp every story mentioning gigawatts with a page promising time travel.

Re:The space elevator is such a joke. (2, Insightful)

LuckyStarr (12445) | more than 10 years ago | (#7675788)

I apreciate your scepticism, but...

In Fact the dictating method here is NOT belief, but lies in the technology itself. If it can be built, it will be. If not... not.

So no reason to be jerky about it. To build one may be a important step forward to becoming perhaps an interplanetary society. So it should be relevant to build actually one. If its made of super-duper nanotube2000 or simply a uniform brick of diamond does not matter. As long as it is built.

Re:The space elevator is such a joke. (1)

WolfWithoutAClause (162946) | more than 10 years ago | (#7675963)

It's not quite as simple as whether it can be built though. I mean, look at Concorde; just building something successfully is not enough.

A space elevator would be more expensive than Concorde to develop and build, and because the asking price to send a payload up it is pretty much the build price divided by how often it is used (plus profit), it may very well not turn out that cheap; I've seen estimates as high as $500-$1000/kg- fairly cheap by todays standards (around $2500-$8000/kg), but probably well within reach of conventional rocketry (and conventional rockets improve to if they can use nanotubes).

Basically, if it takes 2 weeks to climb the elevator, you can't launch all that often, and that pushes up the price.

Re:The space elevator is such a joke. (1)

More Karma Than God (643953) | more than 10 years ago | (#7676378)

>Basically, if it takes 2 weeks to climb the elevator, you can't launch all that often, and that pushes up the price.

Why not? There's no reason (other than the capacity of the elevator) not to launch every two minutes.

I'd be willing to spend two weeks in a box to get to space on a budget.

Re:The space elevator is such a joke. (1)

WolfWithoutAClause (162946) | more than 10 years ago | (#7676510)

All elevators have a certain maximum design load, determined mainly by the thickness of the cable. So it can't carry more than a certain total weight at any one time; so launching every two minutes is probably not possible.

In theory you can make the cable thicker, but this takes time and expense. As an example of one of the issues, since it's thought that the elevator cable will be occasionally cut by meteorites or space junk, it probably doesn't pay you to make it too thick (ultimately you'd spend all your time thickening the cable and then you'd get no use out of it before it falls down.)

I'd be willing to spend two weeks in a box to get to space on a budget.

Yes, well, another problem is that the box goes right through the worst of the Van Allen belts. This means that the radiation is pretty intense; and you'd be pretty fried when you reached the top (by way of contrast the Apollo astronauts were OK, because they went much more quickly through the belts, but even so, they had about 1% of a fatal dose).

Now, it is possible to shield against the radiation, but the thickness is measured in feet, and the weight of the shielding is very considerable- it's looking like early cargoes will not be people.

Re:The space elevator is such a joke. (1)

More Karma Than God (643953) | more than 10 years ago | (#7678662)

There's also the fact that it'd be a huge stationary target for folks wanting to disrupt the economy.

I'm not holding my breath.

PS. Going up in a box would be akin to the folks who deliberately go over Niagra Falls. It's stupid, but some of them survive. Secreting oneself in the center of a bulk shipment of something dense might be doable. Of course while the container may be pressurized for the cargo's sake you'de need to provide your own air purification/recycling. (water and food would be nice too.)

Re:The space elevator is such a joke. (2, Insightful)

PhuCknuT (1703) | more than 10 years ago | (#7680796)

Well the thing is, the space elevator doesn't just go to geosync, it can be used to get to lower orbits too. Why would you take a shuttle when you could take an elevator and save a few million gallons of fuel. Just because it might be dangerous for humans to go through the van allen belts doesn't mean humans can't use it to get to LEO.

Also, regarding launch costs and making the elevator thicker... once you get the first elevator up it becomes much much cheaper to get a second (and third, etc) elevator up. You don't get reliability and high traffic by making the cable bigger, you get it by making more cables. The additional cables will also be much cheaper to build, as they can be lifted and deployed using the first one and the infrastructure to create the cable itself will already exist. This is when launch prices start dropping even more dramatically, to the point that rockets no longer stand a chance of being economical.

With materials like that, Concorde would work (1)

Latent Heat (558884) | more than 10 years ago | (#7677136)

If you had a super-duper composite material to build a space elevator, don't you think getting the mass fraction for a single stage to orbit spacecraft would be a piece of cake?

Graphite composite was supposed to be the revolution in mass fraction that was going to make the X-33/Venture Star workable, and the only thing came down like a house of cards when the composite cryo fuel tank was not all it was cracked up to be.

Re:With materials like that, Concorde would work (1)

WolfWithoutAClause (162946) | more than 10 years ago | (#7677214)

If you had a super-duper composite material to build a space elevator, don't you think getting the mass fraction for a single stage to orbit spacecraft would be a piece of cake?

Possibly. Might even be able to get away with a pressure fed rocket.

Graphite composite was supposed to be the revolution in mass fraction that was going to make the X-33/Venture Star workable, and the only thing came down like a house of cards when the composite cryo fuel tank was not all it was cracked up to be.

Yeah, well, they tried to make an asymmetric, composite, hydrogen tank. One project manager resigned, mainly because of that. If they had gone for cylindrical or spherical they might well have flown.

Re:The space elevator is such a joke. (3, Interesting)

MikShapi (681808) | more than 10 years ago | (#7679019)

Your arguments don't hold water mate.

Conventional rocketry will never be subject to the economy of scale. Too expensive. SE will.

Besides, supersonic passenger jets and Space Elevators are a bad comparison. In fact, you have it all upside down. You should be comparing the shuttle to the concorde, and the SE to the jumbo.
First off,
The tenth concorde is as expensive as the first.
The tenth SE costs a fraction of the first, because - you can use one elevator to raise another in almost no-time.
Then, and here's where you're off, A concorde has a slightly slower alternative that people find sufficient, and that costs significantly less. That's why there's 1200 747's and 12 concordes out there flying.

Next, you're assuming there will be the same amount of orbit-access demand when it costs 500$/kg or 100$/kg as there is now when it costs in the 5-digit/kg.
DEAD WRONG.
The cheaper the price, the more entities seeking space access as an option for their endeavor will open up their checkbooks. What you have is a completely untapped market of organizations - from poorer countries needing satellites, to research, low-grav-manufacturing of chips and medicine (offer a low-enough price and it'll be cheaper to make stuff up there than build centrifuges on earth), Communication satellite networks, power-beaming to remote and inaccessible areas that today require flying in fuel, satellites sent via SE will not need to be overengineered in a way that doubles their cost just to withstand liftoff shaking.

And it doesn't end there.

A SE is also a giant slingshot, making the entire solar system accessible without the need of large-scale LOX/Solid-fuel-rocket/ION/Nuke engines. All you have to do is go to the top and let go. A 91000km SE will slingshot you as far as Jupiter.

You'll get totally new markets - asteroid mining, settling the solar system (more real estate = more population = larger economies = more money to go around etc. etc. etc.).

The SE makes more financial sense than the computer or the automobile. It's a MASSIVE enabling technology that will make possible stuff you and I can't even imagine yet, the same as the people who harnessed electricity 100 years ago didn't exactly have The Internet or global cell phone networks in mind.

It's just a matter of who'll understand it first. NASA, Europe, China or India. Currently, I think China is in the lead.

Re:The space elevator is such a joke. (2, Insightful)

WolfWithoutAClause (162946) | more than 10 years ago | (#7679435)

Conventional rocketry will never be subject to the economy of scale. Too expensive. SE will.

So, if I understand you correctly you are arguing that conventional rocketry will never be cheap because the space launch market it is too small. But the space elevator will be cheaper and so will create a larger space launch market... for conventional rocketry too.

The economies of scale apply just as much to conventional rocketry as to the space elevator- as I say, I've seen the figures for both space elevators and rocketry and it is much more arguable than you seem to think- the underlying, per launch, costs of both are very small indeed (maybe $50/kg); in both cases they are hidden behind the fact you need to borrow billions of dollars to build them in the first place.

Ultimately, the Space Elevator may end up cheaper, but it's not a slam-dunk; and frankly I wouldn't want to bet on it; but I am by no means anti-elevator.

And you're very definitely right about the interplanetary aspects of space elevators; even if it winds up more expensive (it doesn't look like it at the moment, but there's plenty of potentially fatal flaws with them) they are still very much worth building.

Re:The space elevator is such a joke. (1)

ookabooka (731013) | more than 10 years ago | (#7686150)

The only alternative to rocketry or elevator would be a laser powered launch vehicle. Where a laser is shined on a probe that focuses it to a point or ring, generating heat and thrust. Conventional rocketry is very ineficient because of one, single, large reason. You have to carry your fuel. How many pounds of fuel does the space shuttle require to lift off? most of the energy from the thrust is going towards accelerating the fuel. . . big waste of energy.

Re:The space elevator is such a joke. (1)

WolfWithoutAClause (162946) | more than 10 years ago | (#7688919)

Even laser powered launch vehicles need fuel. Remember Newton's laws?

Laser powered launch can use the atmosphere- but only initially- but pretty soon they have to leave it and do the bulk of their acceleration outside; you need to do mach 25 to reach orbit, and nobody has ever achieved more than mach 6 in the atmosphere.

The big advantage of laser powered launch is that it doesn't need to carry the power supply with it. This means that the fuel can be heated far hotter than it would normally- for example pure hydrogen can be used- this means that the exhaust velocity is much higher than if hydrogen/oxygen was used as in the space shuttle (the oxygen is heavy and slows the exhaust speed down). That means that much less fuel is required; however you still need plenty of fuel.

Re:The space elevator is such a joke. (1)

barawn (25691) | more than 10 years ago | (#7687525)

So, if I understand you correctly you are arguing that conventional rocketry will never be cheap because the space launch market it is too small. But the space elevator will be cheaper and so will create a larger space launch market... for conventional rocketry too.

Conventional rocketry can only get so cheap, because fundamentally, you're wasting energy. It can never be as cheap as a space elevator. Fundamentally, the efficiency of a space elevator *could* become a significant fraction of "1" - that is, (energy used)/mgh to get it out of the gravity well. Obviously not 1, and probably not even 0.1, but maybe 0.01 or so. A rocket doesn't have a prayer of reaching that, because it's throwing away so much energy in drag.

More importantly, the economies of scale for conventional rocketry are ill-defined. Can rocket fuel become cheap with more demand? Fundamentally you require a minimum amount of rocket fuel to launch, and so there's a minimum amount of money that you have to spend - it doesn't matter how cheap the rocket fuel gets, it will never be free.

The economies of scale for a space elevator are perfectly well defined. You have an initial cost, and then elevator operating costs, then overhead operating costs. The elevator operating costs can be lowered to virtually zero if need be - the climbers could be powered by the counterweight space station, which is powered by sunlight. If the elevator can't recoup its cost at the demand level it has, oh well, borrow more money, toss up another elevator, and lower the costs by a factor of two, because your capacity just doubled, and your costs remained basically fixed.

The economies of scale apply just as much to conventional rocketry as to the space elevator- as I say, I've seen the figures for both space elevators and rocketry and it is much more arguable than you seem to think- the underlying, per launch, costs of both are very small indeed (maybe $50/kg); in both cases they are hidden behind the fact you need to borrow billions of dollars to build them in the first place.


Fundamentally, this cannot be true. Rocketry uses a consumable. The space elevator does not. I've never seen realistic figures that rocketry could ever get down to $50/kg. With the space elevator, $50/kg is a joke. Even if you assume massive overhead due to elevator maintenance, or massive inefficiencies in the power delivery mechanism (not likely, as it's proven technology), $50/kg is still nothing. All the costs that the NIAC proposal gives ($100/kg) are that high because they are repaying the cost of the elevator.

Anyway, there've been plenty of studies showing the potential market for space applications. The critical mass is about a few $100/kg. Once you hit there, the demand goes sky high. The problem is that you need to get to $100/kg in order for it to go sky high. Rocketry can't do that, because the only way it can get to $100/kg is by making its consumables cheap by creating a huge market. Chicken/egg scenario.

The space elevator circumvents this because fundamentally, its cost/weight is virtually zero, so it's approaching the market from "bottom-up", whereas rocketry is "top-down". The elevator can lower costs to make demand explode, whereas rocketry can't, because they need the demand to lower the price.

Re:The space elevator is such a joke. (1)

WolfWithoutAClause (162946) | more than 10 years ago | (#7689251)

Conventional rocketry can only get so cheap, because fundamentally, you're wasting energy.

Irrelevant. For a rocket, the cost of the fuel/energy per kg of payload is astonishingly low, way down at O($10/kg). The current cost of rocketry, O($1000/kg), is due to other things, primarily because of the low launch rate making the rocket itself expensive and making fully reusable rockets too expensive to develop. Really, the cost of rocketry is because of the standing armies of people necessary to launch- the number of people you need doesn't go up much at all as the launch rate goes up; so the cost amortises away very well.

With the space elevator, $50/kg is a joke.

Yes. But not in the way you mean...

All the costs that the NIAC proposal gives ($100/kg) are that high because they are repaying the cost of the elevator.

That figure is old. The last figure I had from Brad Edwards was above $500/kg. It critically depends on the usage rate; just like rockets. You need to repay the huge loan. $100/kg probably assumes 100% usage, but you can't assume 100% usage of the elevator- where's the market?

The space elevator circumvents this because fundamentally, its cost/weight is virtually zero

It's not. The cost of money is not zero. In a fairly real sense both the space elevator and the rocket are currently, in a fairly real sense, bridges to nowhere. How much traffic would you expect?

Bridges to nowhere. (0)

Anonymous Coward | more than 10 years ago | (#7689755)

Even though I suspect anything beyond an extremely trivial implimentation of a space elevator is flat out impossible.

That really is the reason we're not up there.

What would it take though? What's the super high-value product that would pay back the investment of tens of billions of dollars (if not low trillions) that it would take to really do something? A chip fab on the moon where they made waffers 6? times wider than those on earth? Super-alloys? Very large things produced with CVD and PVD processes? Better superconductors?

What ever they are they'd have to be worth a fantastic amount to a huge market to justify the cost of lifting supplies and launch vehical up to bring them back. Or build vehicals on the moon to deliver the goods to earth (which seems fantastically ambitious).

Re:The space elevator is such a joke. (1)

barawn (25691) | more than 10 years ago | (#7689939)

That figure is old. The last figure I had from Brad Edwards was above $500/kg. It critically depends on the usage rate; just like rockets. You need to repay the huge loan. $100/kg probably assumes 100% usage, but you can't assume 100% usage of the elevator- where's the market?

Jeez, you're actually supporting what I say, just not realizing the implications of it. That $500/kg does not come from the recurring cost of launching materials. It comes from the cost of the space elevator. There's a huge difference. Take a look at LiftPort's financial plan to see why - there are other ways to pay back a loan, but there are not other ways to buy rocket fuel, or pay for the materials for a rocket.

In other words, the cost goes down over time. Or, it starts off much, much lower if the government doesn't care about getting the money back.

Look, the point is not "how cheap will it be?" but "how cheap can it be?" Rockets can only get cheap if there's a huge market for them. The space elevator starts off cheap, and meets market prices.

You said that "reusable rockets are too expensive to develop." Well, that's not really true, as they're being developed right now (SpaceX's booster). In any case, even if you develop reusable rockets, it doesn't matter. You still have to use propellant., which will always cost money, and the only way you get it down to $50/kg is if the market is there to drive economies of scale (i.e. making 1,000,000 liters of rocket fuel is not much more expensive than 100,000 when all costs are taken into account). So rockets need a market to lower costs. A space elevator does not. It lowers the costs to meet market demand. The operating costs of the elevator itself are virtually zero. The operating costs of the business are not, but neither are the operating costs of a rocketry business.

It's not. The cost of money is not zero. In a fairly real sense both the space elevator and the rocket are currently, in a fairly real sense

You don't understand what I'm saying, then. The space elevator requires power to get things into orbit. Nothing else. All of the things you're talking about (paying back the loan) are fixed costs, not recurring costs. Rocketry has recurring costs. It will always cost money to launch rockets. You have to pay for the rocket, after all! With the space elevator, all you need to do is pay for power, and as I said, the elevator could eventually power itself with panels from orbit.

bridges to nowhere. How much traffic would you expect?

I don't have the figures on me because usually I can just point people to the NASA studies that show demand vs. cost-per-pound goes up dramatically at low levels. It *has* to. Right now there's no reason to even consider mining the asteroids. You can figure their net worth, then figure the cost to get there and return them, and it's a losing proposition. If you reduce the cost to get there, suddenly, it's not crazy, it's a business model. Ditto for energy satellites. Then you start talking about commercialization of space, and demand explodes.

Bridge to nowhere? Then why is Delta offering trips into space with frequent flyer miles? There's demand there. It can't be met currently. It will be met eventually.

Re:The space elevator is such a joke. (0)

Anonymous Coward | more than 10 years ago | (#7690913)

I don't mean to break your heart. But LiftPort looks like it is run by a scammer.

Oddly enough, one that lives near me.

The guy has an amazon list [amazon.com] full of get rich quick idiology.

Everything seems to be run out of TuCows.com
some of his ventures (1) [zski.net] (2) [waterworksag.com]

And Brad Edwards "space scientist" (it's amazing what passes for journalism these days) seems well less than sturdy.

Just the fact that they claim to do all their nanotube research and space elevator design work out of one second floor suite in Bremerton is dubious enough. Then the guys other crap, and sell bullshit people will buy it reading list.... Not to mention every article about them and their company is about a grant they've recieved, with no mention of papers published. Yeah. That's extra sketchy. Sure, I haven't gone out to the library to try to find some IEEE, or tracked down any more about the company than where it is.

But given they never delve into the materials beyond a *nanotubes* 'this is the jargon you are looking for' they're just too sketchy, and no one asks the interesting questions.

Re:The space elevator is such a joke. (1)

WolfWithoutAClause (162946) | more than 10 years ago | (#7692679)

And Brad Edwards "space scientist" (it's amazing what passes for journalism these days) seems well less than sturdy.

Brad Edwards has published very legitimate papers on Space Elevators based on a grant from NASA. I've read them; they are excellent work, and they're freely available on the NASA website; he certainly is a well respected space scientist, I cannot comment on his ex-partner.

Re:The space elevator is such a joke. (0)

Anonymous Coward | more than 10 years ago | (#7698228)

You can't have read too deeply about it. The most comprehensive document Nasa seems to have produced is their cp210429.pdf. No where in there do they even mention toughness. It's as if the people investigating a space elevator have never even heard of materials engineering. I might be inclined to believe that if they had their way all suspension bridges would be made of rope and wood!

Yeah, for a space elevator, specific strength is important. Maybe even THE most important attribute. But that doesn't mean toughness isn't critical. They talk about wear from micrometeorite strickes, and the need for constant repair (at least that much is good, as its one of the few times I've seen that mentioned in conjuction with space elevators). But there is still no discussion of crack formation, effects of vibration, the elevator acting as both a heat pump and conductor, and the effects this might have both on their tether and their anchorage. (a steel platform in the ocean with a strong charge?) Not to mention the tapering, and all the charge from friction with the air along it's length. With the high electron mobility of of nanotubes I would expect some pretty impressive currents.

Any elevator coming to the earth (as opposed to a GEO to MEO, or GEO to LEO elevator) has to contend with water. The fine structure of the nanotubes vertically oriented in a ribbon or cable would encourage water to climb the elevator. Which of course introduces problems of it's own. Not the lest of which is ice crystal formation in the tether, and possible vaporization in the lower pressure of the upper atmosphere with the application of a sudden high current.

Vibration, both as it affects corrosion (fretting) and crack formation.

At the very best these documents should be understand to be saying, "Aside from these fantastic immediatly and near term unsolvable problems, there are all these other mind-boggeling challenges we still have to consider. If there is a bright spot in this, it is that there is a material with a specific srength to provide us with permission to keep hoping." Their (Brad's) Phase II will look into asking a couple of the questions I think can be deal breakers.

As I mentioned, about Brad. I would have thought google would have turned up more about him. But it's all space elevators had he made contributions in other areas as well. (Not finding what I want on google doesn't mean it isn't there, it just means I'd have to look up papers he's published and responses to them (if any) in journals like Physical Review letters (where you will sometimes find the most polite flames). It was a pain just to figure out he graduated from the University of Wisconsin and has a post a Los Alamos (his appearent specialty being more to the laser side of solid state physics as opposed to the more material mechanics side).

I've known enough professors, attended enough lecutres, and read enough papers by PhD's to understand that they are just like everyone else except more of their knowledge is confined to a narrower basket. Sometimes they can be profoundly myopic (which might actually be necessary) and brilliant at the same time. That's the comedy part Shakespear talks about in MacBeth. Everyone is stupid about most things all the time, and occasionally we're also stupid when it comes to what we're good at. :)

Stanley? Pons and Martin? Fleischman were well respected before it was revealed they got their PhDs without knowing what convection is. (And that's Ye Olde Will's tragedy part, if you don't have the perspective to understand that ultimately we're all comics in our own right, it can end in sudden tragedy.)

Where's Brad fall in? Myopic but brilliant? Soon to be tragic figure? Blessed with fantastic understanding and foresight (10 billion and 15 years? HAHAHA not likely, but maybe)? Am I an idiot telling a tale? Almost certainly, but is this the part of the tale where against all reason the idiot is right? Time will indeed tell.as I mentioned, I'd have to go out to the university. Hmmm. I wonder if they have a web-based interface for searching for literature. (Oh well, they do, but since I'm just an Alumni, I still have to actually go there.) I can't imagine I'll ever be compelled to put that much effort into tracking down what I am certain is a dead end, but you never know.

Re:The space elevator is such a joke. (1)

WolfWithoutAClause (162946) | more than 10 years ago | (#7691121)

That $500/kg does not come from the recurring cost of launching materials. It comes from the cost of the space elevator.

Yes. In addition what I'm saying is that the up-front cost of a fully reusable space vehicle and a space elevator is about the same.

There's a huge difference.

No. The vast majority of the cost of the rocket comes from the R&D stage of the vehicle; which is a one-time upfront cost. Bending metal is fairly cheap.

You still have to use propellant., which will always cost money, and the only way you get it down to $50/kg is if the market is there to drive economies of scale

No. Look. The typical propellent/payload ratio for a launch vehicle is comfortably under 50:1, usually nearer to 20:1, but let's use 50:1. Let's assume you use hydrocarbon fuel. About 60% of the mass of fuel is LOX- LOX is pennies per pound. Kerosene, perhaps a dollar or two. So the rocket fuel cost is well under $50/kg. That's not a significant fraction of the price. Absolutely no economies of scale are required. Got it?

In other words, the cost goes down over time. Or, it starts off much, much lower if the government doesn't care about getting the money back.

Uh huh. Governments that don't care about money- now we're into science fiction. :-)

Re:The space elevator is such a joke. (1)

barawn (25691) | more than 10 years ago | (#7692702)

No. The vast majority of the cost of the rocket comes from the R&D stage of the vehicle; which is a one-time upfront cost. Bending metal is fairly cheap.

Cheap is not free.

No. Look. The typical propellent/payload ratio for a launch vehicle is comfortably under 50:1, usually nearer to 20:1, but let's use 50:1. Let's assume you use hydrocarbon fuel. About 60% of the mass of fuel is LOX- LOX is pennies per pound. Kerosene, perhaps a dollar or two. So the rocket fuel cost is well under $50/kg. That's not a significant fraction of the price. Absolutely no economies of scale are required. Got it?

Doesn't matter. If you have two systems, one of which has a recurring cost, and one has a one-time upfront cost only, the recurring cost system is going to lose, in the long run. I don't care if you can say "well, they can get it down to $10/kg" - whatever it is, the space elevator can get it under that. The elevator starts from $0/kg, and adds on the up front cost alone.

So you can charge whatever you want. If you have a small market, you charge a lot. If you have a large market, you charge a little. All it does is change the rate at which you pay back the loan.

Uh huh. Governments that don't care about money- now we're into science fiction. :-)

Governments give away money all the time. We call them "grants". They don't expect them to be paid back.

If the US government funded a space elevator to be built, fully, on their own, the launch costs would not be $500/kg. They'd be (virtually) free. Immediately. Instantaneously.

Re:The space elevator is such a joke. (1)

WolfWithoutAClause (162946) | more than 10 years ago | (#7694539)

Doesn't matter. If you have two systems, one of which has a recurring cost, and one has a one-time upfront cost only, the recurring cost system is going to lose, in the long run.

Not necessarily. It depends, quite a bit on all kinds of things. For example, a launch vehicle is going to be cheaper to build in the first place. The recurring costs are only one, small part of the picture.

I don't care if you can say "well, they can get it down to $10/kg" - whatever it is, the space elevator can get it under that. The elevator starts from $0/kg, and adds on the up front cost alone.

I don't care if the elevator per launch costs were to be negative- it still wouldn't necessarily beat launch vehicles.

The energy cost alone is about $10/kg. Then you cannot neglect the amortisation cost of the elevator. The physical structure of an elevator cable looks like it will cost multibillion dollars. The nanotubes are not cheap-currently thousands of dollars per gram. You need 20 tonnes to make even the seed elevator. Further, the elevator has a lifespan- running cars up it will wear it out, over time, there are bound to be maintenance costs, the elevators will be occasionally cut by micrometeorites and space junk (and the estimates are that this will happen often, perhaps every few years.) Also, it takes 2 weeks to get to the top of the cable, a reusable launch vehicle may be able to turn around every day.

You're picking one number, less than 10% of the likely cost, and claiming that because it is lower for space elevators that space elevators will win out. I'm sorry- but your argument is faulty.

Governments give away money all the time. We call them "grants". They don't expect them to be paid back.

Yeah, right, how many multi-billion dollar grants do you know of?

Re:The space elevator is such a joke. (1)

barawn (25691) | more than 10 years ago | (#7703350)

Yeah, right, how many multi-billion dollar grants do you know of?

Isn't that what the US Congress just gave to Iraq?

Or the US Interstate System?

The energy cost alone is about $10/kg.

Not necessarily. If you have loads running up and running down the elevator, the energy cost could be zero (in theory, of course - you can't practically do this). But the elevator could easily be powered from space, where the cost would be zero. You'd need to set something up to deal with the nightfall hours, but it could be done.

Further, the elevator has a lifespan- running cars up it will wear it out, over time, there are bound to be maintenance costs, the elevators will be occasionally cut by micrometeorites and space junk (and the estimates are that this will happen often, perhaps every few years.)

20 years is the target lifespan, and that's several e-foldings down to guarantee it. It'd probably last longer. But it doesn't matter. Economies of scale: build two, build one, doesn't matter.

The nanotubes are not cheap-currently thousands of dollars per gram.

They are made out of carbon. Carbon is cheap. It's the processing that's expensive, and that can, and will, be made cheaper.

You're picking one number, less than 10% of the likely cost, and claiming that because it is lower for space elevators that space elevators will win out. I'm sorry- but your argument is faulty.

No, I'm picking the fundamental number - that is, the lowest it could ever get to.

Look, rocketry has to suck. It throws away far too much energy in heat, and does so quite violently. I'll put this another way. With a space elevator, you don't need massive mechanical engineering to withstand launch stresses (why do you think that satellites fail so often? launch stresses suck), you don't need heat shields to protect for reentry, you don't need fuel to enter any orbit that needs to get to anywhere closer than Jupiter (outward) or Venus (inward). So suddenly satellites, probes, and everything else become even cheaper. If you factor in the increased weight needed, that raises the cost/pound for rocketry quite significantly.

If you want to insist that I can't ignore the initial cost of the space elevator, then you can't ignore the excess weight needed on space payloads in rocketry.

Re:The space elevator is such a joke. (1)

WolfWithoutAClause (162946) | more than 10 years ago | (#7703898)

Isn't that what the US Congress just gave to Iraq?

Yeah, right. In your dreams. Iraq was primarily a play for the Iraqi oil supply.

the elevator could easily be powered from space, where the cost would be zero

How many times can you make the same mistake? Solar panels cost money to buy. Solar panels cost money to launch (even up an elevator). Solar panels wear out. This means that the energy is not free. It may be cheaper, but certainly not cost free.

Carbon is cheap.

Many owners of diamonds would disagree with you.

It's the processing that's expensive, and that can, and will, be made cheaper.

Sure. How much cheaper exactly? Even if it goes down by an order of magnitude, that's still $2 billion for even the seed elevator. That's still atleast as expensive as a launch vehicle, and that's just the seed elevator, very flimsy indeed.

Re:The space elevator is such a joke. (0)

Anonymous Coward | more than 10 years ago | (#7705007)

Isn't that what the US Congress just gave to Iraq?

Yeah, right. In your dreams. Iraq was primarily a play for the Iraqi oil supply.

Yeah, and the space elevator is just a play for the trillions of tax dollars to be made off of interplanetary travel/asteroid mining in the next century or two. The first SE will cost on the order of $10 billion (perhaps cheaper), the second one will cost probably a tenth of that, and fifty years from now, we could toss up a SE for probably under $100 million.

Of course, in 50 years, the SEs we'd be putting up would be able to carry hundreds of tons of payload at a time, launching space tourists off to the far reaches of the solar system, or at least to orbit and to the moon, and we'd be bringing back tons of mined asteroid material every day. The returning asteroid material would easily be able to power a large fraction of the launches, if not all of them, making the operting costs cheaper than rockets could ever dream of, even at $2/gallon for rocket fuel and LOX (yeah right).

To top it all off, the launching of dozens of 2-3 stage rockets everyday, as well as the re-entry of multiple vehicles everyday, would further accelerate the changes to weather that have been seen with commercial aircraft. The SE circumvents this problem.

Carbon is cheap.

Many owners of diamonds would disagree with you.

Now you're showing your ignorance. Diamonds are expensive because of the diamond cartel. It's kinda like OPEC on steroids. Diamonds, if freely released into the market, would cost anywhere from 1/10th to 1/100th their current cost. In fact, the only thing that would keep them moderately expensive is the sheer effort of cutting/polishing the hardest known mineral.

Artificial diamonds can currently be manufactured on the order of $10-$100 a caret, with those prices falling over time.

Once you bring in economies of scale, and the scientists figure out better ways to grow longer strands of carbon nano-tubes and form them into even longer fibers and cables, the price of the space elevator will come down not one, but two or three orders of magnitude.

Re:The space elevator is such a joke. (0)

Anonymous Coward | more than 10 years ago | (#7709750)

Even the dubious liftport estimated 15 billion us, and nasa predicts closer to 40 billion. This is without having done much in the way of modeling material properties like fatigue, thermal fatigue, corrosion resistance (they only plan to check attack by atomic oxygen as of yet), the only source of wear they've considered as of yet is micrometeorites which they expect will keep it in a state of constant repair.

You should look at the 47 page coneption of where space elevators fit in to NASA examination of alternative launch technologies. Right now they're behind railguns! The earth to GEO elevator being at the very pinnical, and a LONG way off if the other technologies they consider more feasible are any consideration. Including the construction of towers a kilometer wide and maybe 20 km tall. While it might be theoretically possible, it's the realm of science fiction, and still simpler than a space eleveator, certainly one reaches street level.

A geo to meo or leo, that's a pretty big technological stretch, but it's not completely fanciful.

Re:The space elevator is such a joke. (1)

barawn (25691) | more than 10 years ago | (#7709249)

Yeah, right. In your dreams. Iraq was primarily a play for the Iraqi oil supply.

I thought that was a pretty obvious joke.

I note that you didn't argue with the second comment, regarding the US Interstate system, which is actually a good analogy.

How many times can you make the same mistake? Solar panels cost money to buy. Solar panels cost money to launch (even up an elevator). Solar panels wear out. This means that the energy is not free. It may be cheaper, but certainly not cost free.

Solar panels will generate more power than can be used to send stuff up the elevator. And besides: solar panels wear out? Most solar panels have a predicted lifespan of 20 years, simply because that's a usual dumb guess as to how long things last. Other than micrometeorite pitting (which can be calculated and dealt with), there's not a heck of a lot that can go wrong with them.

They'll pay for themselves. Energy companies think so. Otherwise British Petroleum wouldn't be helping to fund research in space elevator and space power system technologies.

Many owners of diamonds would disagree with you.

I doubt it. They'd just claim the million-year long manufacturing process makes it worth the money. Besides, artificial diamonds are dirt cheap (compared to regular diamonds), and only going to get more dirt cheap, which only justifies what I said. Carbon's cheap. It's the manufacturing that's expensive, and if there's one thing humans are good at - it's developing manufacturing skills.

Sure. How much cheaper exactly? Even if it goes down by an order of magnitude, that's still $2 billion for even the seed elevator. That's still atleast as expensive as a launch vehicle, and that's just the seed elevator, very flimsy indeed.

C'mon. Now you're just making up numbers. Throw enough money into the development of the process, and the cost could be much, much less. And you don't have to pay that cost back, because it's industrial research. Other things will use it as well.

$20 billion? Reread all the proposals. That's for the total cost of the system. The elevator material itself will probably be a small fraction of that. The usual quote is half a billion to a billion dollars for each elevator - and that's the full elevator, not the seed elevator.

Economies of scale. If they can assembly-line produce a cable which is of sufficient strength - and, if you extrapolate based on current results, it certainly seems like they will, very soon, it'll be dirt cheap. Especially because it won't be just used for the space elevator. Something that has the potential to replace steel cables? That'd become very very quick indeed.

That's the beauty of investing in space elevator technology. It's just material science. Rockets are really only useful for one thing - rockets. I can count on one hand the number of people at my university working on rocket engines. It would take a lot more fingers to count the number of people working on carbon nanotubes.

And that's without the government funding it.

Re:The space elevator is such a joke. (0)

Anonymous Coward | more than 10 years ago | (#7709813)

Did you know that glass is already stronger than steel, and easy to make into cable?

It really is. Carbon too. Silicon Carbide. Lots of things. In fact, by a lot of measures steel isn't actually that idea of cable. It's not very strong, as far as materials go, and it's up there on the density. But it is very tough. And it's stronger that most of the materials tougher than it. But it's also extremely forgiving to work with. It also has a curious property of a fatigue limit. A point that low stain fatigue won't reduce the mechanical stenght below. This is very important. It's something that engineers can trust. They know that if they put their worst case saftey factors and loads on that, the steel will not fail. (Provided they can control things like corrosion, radiation exposure etc.) It vastly reduces the complexity of the problem. There are so many more things that just don't have to be considered. So the problem becomes avoiding hidden secondary effects like the resonant frequency of the Tacoma Narrows Bridge (check any physics text book, the picture is in there).

Specific properties don't always carry the day. How many wodden springs do you have lying around? Wood makes a fantastic spring material after all. Compostis are great, hell they're the future. But they're difficult. You can get that extra 5% of performance maybe in more than one area, at 5 to 50 times the cost. But there are also the negatives besides costs they bring to the table, and those can be formitable, and they need to be tightly controled.

Really what you're expecting, so increadibly flipantly isn't bulk nanoscale materials, which are impressive, but bulk nano-architectured materials on a scale greater than anything has ever been produced. And putting all your hope in a flavor of that.

To illustrate my point, I might ask a couple of questions.

If I have three Silicon Carbide fibers one 1 foot long one 5 feet long, and one 2 inches long, what order would the be most likely to break in and why?

Why when you prick a balloon with a pin will it pop, but if you put tape on the balloon, and prick it through the tape it won't.

Or why do they drill holes into the crack tips where the rock hit your windshield when you take it to get it fixed?

Another good very general question is, "When something breaks why does it make a sound?" (Applies to anything really, snapping stick, ripping paper, the sharp bang of breaking metal)

All very simple elementary questions. That by in large they haven't started asking. Partliy because obtaining sufficent quantities of the materials to get the data is difficult. But considering their ideal case, I would think they could get a pretty decent estimate from crunching the numbers.

Re:The space elevator is such a joke. (1)

WolfWithoutAClause (162946) | more than 10 years ago | (#7710368)

That's the beauty of investing in space elevator technology. It's just material science.

Oh well that's ok then :-)

Guaranteed success is assured!

Why the Concorde is the sux0r (0)

Anonymous Coward | more than 10 years ago | (#7680915)

It doesn't use much in the way of composits and absolutely guzzels fuel. If it were made today it would be much cheaper to operate.

But one real killer is it can only fly supersonic over water.

The people with the big bucks can save a similar amount of time by charternig a flight, if they don't have a Gulfstream at their disposal. And communications networks being what they are, it's not as nessecary. A couple extra hours out of a vacation, against the money one saves it's just not worth it.

-------
Re Space Elevator

They also didn't have sophisticated understaning of solid state physics, crack mechanics, and the ability to predict the performance of a material they didn't yet have in hand.

Yes, the theoretical strengh of the nanotubes is impressive. And it may well be closer to its theoretical peak than any other material. But it won't be at it theoretical peak, and if it was, that won't be the dominant issue in a space elevator. Hence the mention of largest flaw in the original post.

The cracks airplanes are built to tolerate are FEET in length, and airplanes aren't any 35,000 KM from tip to tail. Never mind that the strands in the cable might well be closer to 100,000 KM in length. With no way to repair the flaws. Given the temperature, if a cable did crack to fracture, the elastice response might even cause it to explode! I think that's what everyone would want. A bridge to the stars that might explode at any moment sending supersonic or even hypersonic fragments of in clound, and that which remains possibly into a supersonic (or again much faster decent) uncontroled landing into it's anchorage. Nice!

Why is it that every endorsement of a space elevator starts with the presumption that it's not only possible, but relatively straight foreward? As if the only significant problem is making long nanotubes. That's not even the hard part.

If nanotubes are so great, even at cryogenic temperatures, rockets will be made out of them far before a bridge cable, let alone a space elevator. Hell that space plane plagued with fantastic technical hurdles and cost over-runs would be lighter and more feasible.

The Foo Fighters have left Groom Lake (0)

Anonymous Coward | more than 10 years ago | (#7680316)

That's just it, guy. You've got no idea what I'm talking about.

FWIW. Diamond is strong, not tough. Which means it shatters, like glass, which is also strong. (More so than steel, but guess which wins in a fight?)

My scepticism isn't flamebait, and your ignorance, well it shows us a little something about our moderators doesn't it.

I love it though. You look at a set of insane obsticles, which you don't understand, and counter it with an emotional plea. It's every bit the flight of fancy that time travel, faster than light anything, and trips to the center of the earth are.

I might as well assert that we should just spend our time praying really hard so God magics our asses to Mars. It *could* happen! Right? And if it deosn't, oh well.

Perhaps it's arrogant and self-rightious of me to assume that people should have a deep understanding of the world we inhabit and the laws that govern it. After all, I don't run through the streets shouting "Santa Clause is just made up!" at Christmas. But when you see things like Space Elevator this, UFO conspiracy that, it's hard not to have at least a little contempt for people who should know better but choose not to.

Re:The Foo Fighters have left Groom Lake (1)

LuckyStarr (12445) | more than 10 years ago | (#7724975)

Your are of course right. I am not aware of every bit of aspect of the SE, as it would require a lifetime worth of study. Do you?

I doubt you can calculate every nuance of orbit-subtlty it would require to make this whole thing work. Not to speak of the strength of the material and the inner structure it would require to stop cracks from distributing further. [Insert favourite field of research here] This is left to the experts.

ALL I say is, do not judge it beforehand. May be there is emotion involved, but is that a problem?

Re:The Foo Fighters have left Groom Lake (0)

Anonymous Coward | more than 10 years ago | (#7734389)

Actually I do know a little something about fracture mechanics, and materials science. (All that Metallurgical Engineering has that side effect)

And what little I've done with composites has given me tremendous appreciation for how much more complicated solving problems with them becomes despite their frequently tremendous advantages.

Funnily enough the experts, don't seem to be the ones asking the questions at this stage of the proposal. Too bad, maybed they'd have something more useful than wishful thinking by now. They have physicists who seem to be in fields adjacent to their specialties. As opposed to the Ceramic, Materials, Mechanical and yes Civil engineers they should probably be involving.

A space elevator is one of the few technical challenges that makes commercial fusion power seem to be a pragmatic short term pursuit. The specific strength is important, but it isn't all important. The Tacoma Narrows bridge was more than strong enough for it's job, until they discovered they built a bridge that resonated with the wind in the Tacoma narrows. This, just from that one secondary effect which destroyed a bridge in an afternoon, and taught civil engineers all over the world a valuable lesson, is a vastly greater threat to the space elevator (principally the earth to L/M/GEO varieties) because it's going to be so much longer and be able to resonate with so many more frequencies, which will have so many more possible sources because of it's fantastic size.

The start of any undertaking like this, consuming tens of billions of dollars and untold lost opportunities, demands a great deal of scrutiny. The tremendous outlay of resources demands it. When projects this big are involved, emotions place is limited to one of inspiration or cheerleader. Not prophet. That kind of shit will get you lost in a desert for forty years.

I wish I could in some way impart to you the enomity of the technical hurrdels. To compare a space elevator to other great engineering achivements is fruitless. In comparison, even considering the time in which they may have been built, they are truly insignificant. Maybe if an acient people has actually built a mile high tower our of stone that would be close.

Re:The space elevator is such a joke. (1)

jo42 (227475) | more than 10 years ago | (#7727335)


And when it collapses, it will wipe out millions of people.

Re:Heh (1)

WolfWithoutAClause (162946) | more than 10 years ago | (#7675574)

Unfortunately, it needs to be on average 35,000 Km away to work.

Something of a misconception. In actual fact an elevator cable has to be attached to the elevator car for the system to work correctly.

Re:Heh (0)

Anonymous Coward | more than 10 years ago | (#7687114)

Give a slashdotter one small "story" about an inch of nanotube and s/he takes 35,000 km for an elevator "thread" which stretches a mile.

How about a "moon leash"?... (4, Funny)

kommakazi (610098) | more than 10 years ago | (#7675370)

Well since I've just recently been told that the moon actually is moving away from the earth (see this [slashdot.org] thread) we really ought to leash the moon to the Earth to prevent this. I like the moon where it is. I suppose it could double as an elevator....

Re:How about a "moon leash"?... (1)

OldMiner (589872) | more than 10 years ago | (#7675482)

I appreciate the humor, but please note the distance of the moon is around 60 times the radius of the Earth [nasa.gov] . Meanwhile, proposed space elevators represent at most 7 Earth radii out. That's one heck of an increase for an already gigantic budget.

Re:How about a "moon leash"?... (0)

Anonymous Coward | more than 10 years ago | (#7675494)

Considering the moon is not in Geosyncronus orbit that would be very difficult to do... Unless you wanted to use a nanotube to cut the earth in half... Yeah that might work.

Re:How about a "moon leash"?... (1)

kommakazi (610098) | more than 10 years ago | (#7675547)

I would just like to let it be known that there was no real seriousness in my original post...

Re:How about a "moon leash"?... (1)

kommakazi (610098) | more than 10 years ago | (#7675566)

...though with a sort of track encircling the globe that the end of the nanotube could attach to and run freely in....


it would still fail miserably.

Re:How about a "moon leash"?... (1)

More Karma Than God (643953) | more than 10 years ago | (#7676397)

And we could put generators in the track to make free electricity! Wheee!!!

Re:How about a "moon leash"?... (1)

PhuCknuT (1703) | more than 10 years ago | (#7680856)

not that I think you were even remotely serious about that, but it could never work anyway, as the moon a) doesn't have a circular orbit, and b) doesn't follow a fixed path relative to the surface of the earth.

Re:How about a "moon leash"?... (1)

spitzak (4019) | more than 10 years ago | (#7676429)

Attach the moon leash to the North Pole! Easy!

You need a swivel connector, though.

Re:How about a "moon leash"?... (1)

Alsee (515537) | more than 10 years ago | (#7681786)

The moon is receding from the Earth at about 1.5 inches / 4 cm per year, and has a mass of 161700000000000000000000 pounds / 73500000000000000000000 kg. I'll skip the 12 pages of calculations and just say it works out to about 3 or 4 terawatts of continuous energy. Leashing the moon would stop the recession, but it would merely redirect that energy into constantly accelerating the moon faster and faster spin around the Earth. As we all know, the faster you spin something the harder the centrifugal pulls outward. The pull on the leash be enormous and constantly increasing until the moon was eventually whizzing around the Earth once per day.

Someone else suggested attaching the leash at the North Pole with a swivel, but that would be totally lopsided, it would yank and spin the Earth causing untold havok. You'd need one swivel at the North Pole with a single leash running out to the moon and back down to another swivel at South Pole. The moon would be at the tip of the triangle and it would have to have a pulley system allowing it slide up and down the leash to account for the Earth's tilt.

Yeah, I know you were joking. Geek humor: must work out calculations and design a properly functioning system. :)

-

Actual strength? (4, Insightful)

IANAL(BIAILS) (726712) | more than 10 years ago | (#7675576)

The Space Elevator can't be far away now..."

I think that's more than a little bit premature. Sure, it seems like we can make them a little easier now in the lab... but as an earlier poster mentioned, we're going to need some pretty long lengths to streach into orbit. Nowhere have I heard how exactly the little fibres that are grown in the lab will be joined together *at the usual nanotube strength* over and over again to make these long lengths.

Won't the 'joints' between individual fibres be a weak point in the system, and since we're joining thousands (if not millions) of little tube lengths in the lab, won't that have a rather large impact on the actual strength of the tube (vs if it was actually one long continuous length)?

Re:Actual strength? (1)

orkysoft (93727) | more than 10 years ago | (#7675774)

Nah, they'll probably use some super glue and Camel Books ;-)

Re:Actual strength? (4, Informative)

barawn (25691) | more than 10 years ago | (#7675909)

I think that's more than a little bit premature. Sure, it seems like we can make them a little easier now in the lab... but as an earlier poster mentioned, we're going to need some pretty long lengths to streach into orbit. Nowhere have I heard how exactly the little fibres that are grown in the lab will be joined together *at the usual nanotube strength* over and over again to make these long lengths.


Wow, that's surprising, considering that Slashdot has had plenty of explanations as to how you do it. :)

Nanotube strength is more than you need. Much more. Pure carbon nanotube strands are strong enough to make a completely untapered elevator, all by themselves. (300 GPa tensile strength).

For a space elevator, you're not building one continuous nanotube to orbit. That'd be insane. What you do is you build a composite fiber, just like you have fiberglass, or Kevlar fibers - you dope some composite with nanotubes to increase their strength.

Now, you may say "so what? they still have to build them!". They have. Kilometer-long doped CNT fibers have already been produced. No, they're not as strong as you need. Yes, that's being worked on, and yes, it's an engineering problem, not a fundamental flaw. Once you've got kilometer-long length, it's not much more of a step to be thousands of km long (believe it or not). At *absolute worst* you could build a system to join segments of the elevator together. There have already been presentations and ideas on this theory, and it's perfectly sound.

There is nothing fundamental preventing the space elevator from being built. It's just a matter of time, and this is one (very large) step along the way. But it's important to remember that it's just engineering problems - big, but tractable.

Re:Actual strength? (3, Informative)

WolfWithoutAClause (162946) | more than 10 years ago | (#7676357)

Nanotube strength is more than you need. Much more. Pure carbon nanotube strands are strong enough to make a completely untapered elevator, all by themselves. (300 GPa tensile strength).

Nope. That's a theoretical maximum strength; but the theory is probably wrong. Current experimental strength of short fibers is about 120 GPa, and that's only just what you'd need to do this (about 60 GPa is needed, plus a safety factor of say 2).

What you do is you build a composite fiber, just like you have fiberglass, or Kevlar fibers - you dope some composite with nanotubes to increase their strength.

Not quite. If you dope a plastic with nanotubes you'd end up with a material whose strength and weight were dominated by the polymer. That would be wayyyy too heavy and weak. The idea is that you have to use an absolute bare minimum of glue to stick the nanotubes fibers together. Trouble is no-one knows how to do this right now with adequate strength; nanotubes are slippery and particularly hard to glue; and as noted, we don't have a great deal of strength to play with- we need a safety factor for practical reasons.

Kilometer-long doped CNT fibers have already been produced. No, they're not as strong as you need. Yes, that's being worked on, and yes, it's an engineering problem, not a fundamental flaw.

Those fibers aren't even as strong as Kevlar. So, no, it's still a research problem. The engineering begins when we have a cable even a few feet long; of the right strength/weight ratio. Until then- engineers and financiers must hang fire.

Re:Actual strength? (0)

Anonymous Coward | more than 10 years ago | (#7677219)

If the theory is probably wrong, then it's about as reasonable that the maximum could be higher. The current experimental maximum doesn't decide the matter either way.

A safety factor of 2 is extreme; at least a test elevator could be built with a much slimmer safety margin, just to prove the concept.

Also, a space elevator could be built with steel cables, if you had the money to lift it all into orbit. So it's not an engineering problem nor a research problem, it's really a financial problem. The engineering and research is just to bring the price down to make it economically feasible.

Nobody's actually made a cable out of these extra-long nanotubes yet, so we should probably wait until they have before we start concluding how they'll adhere; a sufficiently long fiber will stick to itself fairly well. The slipperyness of carbon nanotubes is something which isn't well-understood, and it varies considerably.

Re:Actual strength? (1)

liftwatch (731474) | more than 10 years ago | (#7678206)

If the theory is probably wrong, then it's about as reasonable that the maximum could be higher.

I think that the original poster meant not that the theoretical maximum strength for CNTs was WRONG... just that there might be other factors, as yet undiscovered, which may also limit the maximum strength. It is much more likely that the maxiumum strength of CNTs will be LESS than 300GPa than it is the strength will be GREATER than 300GPa.

Also, a space elevator could be built with steel cables, if you had the money to lift it all into orbit.

Not true. Steel does not have anywhere near the tensile strength needed to support even its own weight from GEO. Steel has 5GPa max. Something closer to 100GPa is required for a space elevator.

Re:Actual strength? (1)

laertes (4218) | more than 10 years ago | (#7684366)

Actually, you can logarithmically taper the elevator to make up for low tensile strength. The problem is of course, that at GEO (where the tapered elevator would be thickest) the damn elevator would be wider that North America. I don't even know if we could make that much steel without mining below the crust, but it's a pretty mental picture...

Nanotubes are sticky (4, Informative)

jgardn (539054) | more than 10 years ago | (#7677862)

The nanotubes are sticky and bond well with themselves. Read the article.

The process they describe here is a way of storing the nanotubes for transport, so that they can be assembled later.

Creating nanotubes is dead-on easy. I've actually seen a nanotube creation lab in the Physics department in the University of Washington. I think it is on the third or fourth floor. Go visit there if you get a chance.

After the nanotubes are created, they have to be seperated. They come in a hairball and need to be seperated individually. Next they are stored in a liquid type suspension. When they want to form their nanotube rope, they need a way to squeeze them back together again and extract all of the liquid. The liquid described in the article is beneficial because it helps organize the nanotubes so that they can be easily extracted. You will end up with 100% pure nanotube rope or cable at the end of the process.

Now you are probably speculating that it can't be that simple. It is. Sheep hair (wool), cotton fiber, polyester, and such all work in the same way.

Re:Nanotubes are sticky (1)

liftwatch (731474) | more than 10 years ago | (#7678162)

The nanotubes are sticky and bond well with themselves. Read the article.

While this is true, for a sufficiently strong composite material we will also need the nanotubes to bond well to the substrate polymer. Although CNTs are attracted to each other, they tend to have featureless, smooth surfaces that don't bond well with other materials. The likely solution to this problem is a process called 'functionalization' which adds features -- small appendages -- to the CNTs so that there is more traction within the substrate. More work is required here, but some recent developments [liftwatch.org] are encouraging.

Re:Nanotubes are sticky (2, Interesting)

WolfWithoutAClause (162946) | more than 10 years ago | (#7679547)

The nanotubes are sticky and bond well with themselves.

Absolutely. But the fur-balls haven't previously achieved anything like their full strength potential.

Creating nanotubes is dead-on easy.

Yup. But the problem is creating 120GPa nanotube cable- nobody has ever done that so far.

You will end up with 100% pure nanotube rope or cable at the end of the process.

True, but that doesn't make it strong. Furballs have not massive strength. The microstructure of the 100% rope is completely critical. The nanotubes have to be almost perfectly aligned along the length of the cable, with just enough crossconnects to keep the cable together. Any nanotubes that are at a significant angle weaken the cable.

I mean, take steel. Steel is orders of magnitude weaker than single filaments of steel. Or glass, same thing- that's why glass fiber is so strong in fact (single filaments are usually much, much stronger than bulk material.) Until somebody can show that carbon nanotubes made in this way lose less than 25% of their theoretical strength, I think I'm pretty justified in being atleast a little skeptical; albeit hopeful. As I noted the article didn't claim anything as regards strength/weight ratio.

I admit it sounds very promising, particularly since this is similar to how Kevlar is made...

(Crossing fingers).

Re:Actual strength? (1)

Rick the Red (307103) | more than 10 years ago | (#7681027)

it's still a research problem. The engineering begins when we have a cable even a few feet long
I've been reading this thread with great interest, and I agree with points made by both sides. However, IAAE (I Am An Engineer), and I wish to point out that there's a fuzzy line between Physics and Engineering. When Roebling [greatbuildings.com] invented wire rope, was he a Physicist or an Engineer? At what point did his work transition from Research to Engineering? If you asked him, he'd say he was an Engineer and all his work was Engineering.

The headline (you did RTFS, right?) says it all: "Rice engineers make first pure nanotube fibers"

Re:Actual strength? (1)

WolfWithoutAClause (162946) | more than 10 years ago | (#7681912)

The headline (you did RTFS, right?) says it all: "Rice engineers make first pure nanotube fibers"

Yeah, I did, and I've read most of the NACA research papers on space elevators too. Please tell me where, when you RTFS, where it says that the material they made had a strength/weight ratio sufficient to make a Space Elevator. Until that has been demonstrated it's material science; which is really very much more basics physics research than engineering.

Re:Actual strength? (1)

Rick the Red (307103) | more than 10 years ago | (#7684337)

Ah, but the Rice engineers weren't working on space elevators, they were working on nanotube fibers. To the space elevator engineers perhaps this is still physics research, but to the nanotube cable makers (with applications beyond space elevators) this is engineering.

I said it was a fuzzy line...

Re:Actual strength? (1)

WolfWithoutAClause (162946) | more than 10 years ago | (#7685899)

It's not engineering, it's research. It so happens that the researchers here are engineers and chemists, but it's still research.

Re:Actual strength? (1)

barawn (25691) | more than 10 years ago | (#7687417)

ALL good engineering is research, by that definition, because they're doing something that hasn't been done before. When engineers design a new fiber-optic network that's faster than any other network in the world, that'd be research? When engineers design *anything* that's better than what's been done before, that's research?

The difference between "evolutionary" progress in science and "revolutionary" progress in science are pretty well understood. You can speed up "evolutionary" progress by throwing money at them. You can't speed up "revolutionary" progress in science the same way.

What you call research is just evolutionary progress, which is what I call engineering. The point is that no new "revolutionary" progress needs to be made. CNTs exist. They can make a space elevator. The problem is now how to do it. This isn't a small problem. But it is tractable, and more importantly, it can be sped up just by throwing money at it.

Re:Actual strength? (1)

barawn (25691) | more than 10 years ago | (#7687389)

Nope. That's a theoretical maximum strength; but the theory is probably wrong. Current experimental strength of short fibers is about 120 GPa, and that's only just what you'd need to do this (about 60 GPa is needed, plus a safety factor of say 2).

Early experimental strength is 1/3 to 1/2 of what theory predicts, and the theory is probably wrong? The theory is for pure nanotube fibers, based on carbon-carbon bond strength. Considering early experiments are so close to the theory, it's probably correct.

And 60 GPa, again, is what you'd need for a cable of the design listed in the NIAC proposal. You can steal a bit of strength by tapering the cable more. It just gets a little silly after a while.

Not quite. If you dope a plastic with nanotubes you'd end up with a material whose strength and weight were dominated by the polymer. That would be wayyyy too heavy and weak. The idea is that you have to use an absolute bare minimum of glue to stick the nanotubes fibers together. Trouble is no-one knows how to do this right now with adequate strength; nanotubes are slippery and particularly hard to glue; and as noted, we don't have a great deal of strength to play with- we need a safety factor for practical reasons.

Again - if worst comes to worst, you use pure nanotube fibers. It *must* be possible to fuse them together (it's already been done, on a small scale). Scaling it up to produce almost a hundred thousand kilometers may be prohibitively expensive, but that's virtually the definition of an engineering problem.

Those fibers aren't even as strong as Kevlar.

Because they weren't intended to be. No one is trying to make space elevator cable right now. That would be like trying to run before you walk. What they're trying to do is make a scalable process, then you improve the process.

You think Kevlar was as strong as kevlar when it was first invented? Not likely.

The engineering begins when we have a cable even a few feet long; of the right strength/weight ratio.

No, then the space elevator engineering begins. Right now the nanotube engineering is taking place. But it's an engineering problem. A solution has to exist.

Let me put this another way. If SETI discovered a message from the stars tomorrow, and they were sending us images of their home planet, and they showed a space elevator made out of carbon nanotubes, we would not ask "how is that even possible?", which we would have asked 20 years ago. We would ask "how did you get good interfacial adhesion with the nanotubes?" or "how did you produce nanotubes of such length?", which are engineering questions, not physics questions.

I'm not disagreeing with you - there's still plenty of distance left to go. But some people try to write the space elevator off as if it will never happen. Those people are like the people who claimed we'd never break the sound barrier. It will be possible - it's "evolutionary" science, not "revolutionary" science.

Re:Actual strength? (3, Interesting)

nanobug (446693) | more than 10 years ago | (#7679221)

"Won't the 'joints' between individual fibres be a weak point in the system...".

Not necessarily, it depends on how you join them. You need to ensure that the joints are totally seamless so there are no weak points.

See nanodiamond.info [nanodiamond.info] for an example of how to join them which increases the overall strength (or strength to weight ratio) rather than weakens them. The trick involved actually lets you use them for buildings and bridges under compression as well as cables under tension. Warning: shameless plug (I wrote the site), but well worth looking at anyway IMHO.

Re:Actual strength? (1)

*themotterfukker* (720134) | more than 10 years ago | (#7695063)

I'm not thinking of the strength, I trust in the durability and strength. I'm more concerned about all that "flak" in form of broken dead satellites out there.
It's like trying to avoid a gunshot, only this time it's rotating, and in size of a fist...

How come noone talked about that yet?

Yes! One more step! (1)

akgunkel (567825) | more than 10 years ago | (#7675590)

Awesome, we've made one more step towards a Space Elevator! Unfortunately, we've still got about 100,000 more to go... but hey, progress is progress.

They don't mention the strength (3, Informative)

WolfWithoutAClause (162946) | more than 10 years ago | (#7675602)

Just because something is made of nanotubes doesn't make it strong, it depends on how they are laid out. The press release sounds good, but until they publish the measured strength/weight ratio of a few feet of their manufactured cable. (The data might be in the paper, but I haven't bought it. Anyone?)

Acid? (1)

Bowling Moses (591924) | more than 10 years ago | (#7675632)

So why concentrated sulfuric acid I wonder. Would a concentrated solution of a different strong acid work as well? If it's just acidity to get increased solubility, why not a superacid like HF-SbF5? Any organic chemistists out there?

Re:Acid? (1)

A55M0NKEY (554964) | more than 10 years ago | (#7676348)

They said it was basically the same process used to make Kevlar. If you were a chemist that knew how to make Kevlar it seems fairly logical to try and apply that technique to carbon nanotubes.

Re:Acid? (0)

Anonymous Coward | more than 10 years ago | (#7680827)

A superacid of that strength is perfectly capable of chopping carbon compounds into tiny pieces.

just the space elevator? (1, Interesting)

Transcendent (204992) | more than 10 years ago | (#7675745)

Why not use the nanotubes for high temperature super conductors?

A.K.A. Fast @ss processors with minimal heat.

Or for more scientific and broader uses, much much much much better inductors (another boost to computers), solenoids (yea yea, same thing), electromagnets (umm, sort of different) for magnetic levitation used in maglev trains, etc...

Good times await.

Re:just the space elevator? (1)

FooAtWFU (699187) | more than 10 years ago | (#7675856)

Are the nanotubes, then, superconductive by nature? fun stuff, if they are.

Re:just the space elevator? (2, Informative)

chainsaw1 (89967) | more than 10 years ago | (#7680832)

Some of this research has already been done. I know isolating metal ions and atoms inside C60 and fusing the resulting C60 into a tube (or bonding them close to each other) does not display superconductive properties.

I would suspect fullerines have similar conductance to graphite

Plus, a previous slashdot story indicated that fullerines undergo total disentegration under some conditions [slashdot.org]

Nanotubes as transistors [slashdot.org]

NAnotubes extend battery life [slashdot.org]

Re:just the space elevator? (1)

WallsRSolid (591098) | more than 10 years ago | (#7680833)

Nanotubes' 20 K critical temperature (T_c) does not come close to a high temperature superconductor.

High T_c is usually defined as above the boiling point of liquid nitrogen, a good, cheap, plentiful, environmentally-friendly coolant, which is 77 K. This implies that liquid nitrogen can be used to keep the material superconducting, a property which drops costs and engineering challenges dramatically. Nanotubes' more popular and practical properties are its tensile strength (i.e. space elevator), and its *thermal* superconductivity (i.e. badass heatsink).

Furthermore, it's ideal for high-power electrical transformer applications because it conducts electricity with low resistance in only one dimension, eliminating pesky, dissipative eddy currents. A friend of mine patented this application.

----
e+ ---> <--- e-
Fatal Attraction

not the first (1)

js7a (579872) | more than 10 years ago | (#7675878)

This would be a dupe [slashdot.org] , if it weren't for the two different (nearby) universities.

Canadian Carbon Nanotube Product of the Future ... (1)

fygment (444210) | more than 10 years ago | (#7676052)

... is Duct Tape. That's where the money of the future is and you heard it here first on /.

And that will allow the Canadian government to keep it's existing military equipment flying and floating well into the 22nd century.

so a space elevator isn't next... (1)

constantnormal (512494) | more than 10 years ago | (#7676260)

... but what about molecular monofilament fibers?

or bulletproof clothing? Seems like a fabric made of this stuff could make a mighty fine lightweight aircraft skin, or a parachute that folds up into a money belt, or....???

Re:so a space elevator isn't next... (4, Funny)

A55M0NKEY (554964) | more than 10 years ago | (#7676454)

Year: 2009

Place: Wal*Mart

Blotter: A bearded armed thug wearing a stylish black blouse was killed while trying to hi-jack the daily armored car. The purp was struck with a .357 caliber round which entered his chest and left his back.

Witnesses report that upon falling to the ground the woman's blouse was missing. Apparently, the robber thought the high tensile strength of Jaquline Smith's new line of clothes would protect him from any bullets. What he didn't consider was that the nylon stitches that held it together would tear and that the round would pull the entire blouse off his back, taking it in through the bullet hole and out a grapefruit sized hole in his back eventually ending up imbedded in the door of an Oldsmobile in the parking lot.

Police finding the round still wrapped in the pretty - if bloodsoaked, blouse, impounded it as evidence.

Carbon economy (1)

MrLint (519792) | more than 10 years ago | (#7677132)

Reading about this really seems to me to be an important break-thru, it started me to think if we are on the border of moving away from a metal/plastic based manufacturing economy toward a carbon based one. For many many everyday uses replacing metal/ plastic. beverage containers can openers and so on. The question i suppose is, does this needs to be recycled ?

Re:Carbon economy (0)

Anonymous Coward | more than 10 years ago | (#7690224)

Plastic _is_ carbon

Re:Carbon economy (1)

MrLint (519792) | more than 10 years ago | (#7690857)

no doofus, plastic is a hydrocarbon. please go back to chemistry 101

Technical data on Space Elevator (4, Informative)

marcus (1916) | more than 10 years ago | (#7677294)

I don't know how many are interested and yet don't know about these pages but here is some good stuff for dreamers to read...

Institute for Advanced Concepts [usra.edu]

and here is a design study for a space elevator:

Space Elevator Phase 1 [usra.edu]
Space Elevator Phase 2 [usra.edu]

Space elevator news/portal (2, Informative)

liftwatch (731474) | more than 10 years ago | (#7678269)

I'm glad to see so many space elevator stories on Slashdot lately. I think the actual feasibility of this idea is important to impress upon people. SE research has a considerable amount of NASA funding, the fruits of which where the Phase I & II NIAC reports mentioned in the parent post.

LiftWatch.org [liftwatch.org] is a news/portal site dedicated to following this and other developments in space elevators and related technologies. Besides the main front page news, here are some handy links for the SE afficianado:

I've been trying to get Slashdot to add LiftWatch headlines as an RSS feed. If you find the site interesting, please let the /. editors know so that there can be a LiftWatch.org slashbox.

I RTFA , how do you cut the nanotubes? (1)

annisette (682090) | more than 10 years ago | (#7677934)

That is pretty much it, having a one meter nanotube or better yet a woven bunch of nanotubes and you need the length trimmed to i/2 meter? Lazers, plasma torch, sharp pair of sissors, acid?Actually I only skimmed read the article so if the answer is there, take it easy.

Re:I RTFA , how do you cut the nanotubes? (1)

Xner (96363) | more than 10 years ago | (#7678771)

I'm pretty sure you could just burn through it. After all, it's rolled up graphite sheets, and those can be made to burn with minimal effort.

Invisbly cut someones throat (1)

Frans Faase (648933) | more than 10 years ago | (#7678472)

One of the dangers of long nanotubes is that they are extremely strong compared to their thickness. This makes them ideal for cutting purposes. I guess one of the dangers of long nanotubes might be that people can be cut. Imagine (accidently) cutting someones throat with a fiber thinner than a hair, which is almost invible to the eye.

Re:Invisbly cut someones throat (2, Informative)

jpop32 (596022) | more than 10 years ago | (#7678834)

Imagine (accidently) cutting someones throat with a fiber thinner than a hair, which is almost invible to the eye.

Wiliam Gibson, "Johhny Mnemonic"? IIRC, it features a japanese dude with a 'monomolecule' spooled in his thumb, used for exactly that purposes.

Re:Invisbly cut someones throat (1)

PhuCknuT (1703) | more than 10 years ago | (#7680929)

I think that was in Neuromancer, but I could be wrong.

Re:Invisbly cut someones throat (1)

rleibman (622895) | more than 10 years ago | (#7681830)

You've been reading too much Niven <grin>

Re:Invisbly cut someones throat (1)

johndiii (229824) | more than 10 years ago | (#7796767)

Ringworld. Nessus loses a head. Something like 30 years ago, right?

the real deal (4, Interesting)

Goldsmith (561202) | more than 10 years ago | (#7681206)

This is actually what we've been looking for.

A way to self-assemble nanotubes into ropes which can be used macroscopically. Whether or not it's strong enough to use in a space elevator remains to be seen, but we can actually talk about trying that now!

The nanotubes which were used here are electronics grade tubes, that means that most likely they were single or double walled (single walled being the strongest possible), and had a very low defect density. This is obviously important to the mechanical strength.

I work in a nanotechnology lab, and part of my job is to grow nanotubes. They naturally come in ropes which are around 1 to 10 nanometers in diameter and a few microns to a centimeter in length. The tubes are held together in solution due to van der Waals forces (basically friction) which are absurdly high for nanotubes. We've been separating tubes from eachother in solution from years, but efforts to re-align them have focused on the air-water interface. All they have done is found a solution which will solvate more tubes, to the point that the tubes have no room to run "against the grain" and so become aligned. This is done all the time with polymers. In retrospect it seems obvious and easy (it wasn't).

I remember a week ago Smalley was being bashed here about his conflicting views with Drexler on the future of nanotechnology and molecular assemblers (versus self-assembly). If you'll notice, Smalley is on this paper. This is why he has a Nobel prize, and why he disagrees with Drexler, self-assembled nanotechnology is already here, and it's only going to get better.

Not likely (1)

O2dude (460818) | more than 10 years ago | (#7681357)

The space elevator wont happen as it is hard to secure from people who what to pressure or embarrass the people that built it.

Consider how easily a cessna or some other flying craft filled with delusional muslims, white power supremacists, 7th day adventists or some other crackpot-du-jour, can be flown into it and cause major embarrassment to the spineless politicians that declared it perfectly safe.

On the other hand the politicians might be able to blame it on the autoprompter, in which case it's all due to underfunding of the space agency that put the Space Elevator up... do I hear anybody mutter 'conspiracy'? ;)

Re:Not likely (0)

Anonymous Coward | more than 10 years ago | (#7684869)

Well, for various technical reasons it'll be based way out in the ocean, away from normal flightpaths. And it's critical infrastructure, easily worth keeping a carrier group around to guard it. Taking it out won't be so easy as that.

Re:Not likely (1)

drinkypoo (153816) | more than 10 years ago | (#7695575)

The only place to put the space elevator is at the equator. The best place to put it is over the ocean. The area for quite some distance around the space elevator can be a no-fly zone (at least, barring those aircraft whose destination is the elevator) and anything which violates its airspace can be warned and then blown out of the sky.

The only thing with a real chance to damage the space elevator will hence be a stealth aircraft or a cruise missile.

SWNTs (0)

Anonymous Coward | more than 10 years ago | (#7682094)

Does this have any effect on the development of new solar cells that use single wall carbon nanotubes?

This wasn't done yesterday (1)

JohnPM (163131) | more than 10 years ago | (#7682180)

Did anyone else notice the date in the corner of the image? It's Febuary 2002. I guess it takes a long time for this kind of reasearch to go from the lab to the media.

The other way of doing it is basically the cold fusion method (call a press conference immediately). Pros and cons. :)

Shigawire (1)

Doc Ruby (173196) | more than 10 years ago | (#7687675)

Everybody's getting excited about the tensile strength of buckytubes: 600x that of steel, by mass. Space elevators, drug delivery, yadda yadda yadda. What about shigawire [technovelgy.com] , an essential technology proposed by Frank Herbert in his epochal _Dune_ novels? Similar to Larry Niven's monomolecular filaments, these prefigures of long buckytube strands are used for vast data storage, and for slicing through any material, even "plasteel", like a knife through butter on their monomolecular "edge". Where's the 100m buckytube with my genome on it, with which I can rappel down a cliff face, and slice a loaf of bread into julieanned splendor?
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