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Space Elevator An Impossible Dream?

Zonk posted more than 7 years ago | from the sniffle dept.

448

bj8rn writes "Three months ago, the dreams of a space elevator finally seemed to be coming true after a successful test. An article in Nature, however, suggests that there's reason to be pessimistic. Ever since carbon nanotubes were discovered, many have been hoping that this discovery would turn the dream into reality. Pugno, however, argues that inevitable defects in the nanotubes mean that such a cable simply wouldn't be strong enough. Even if flawless nanotubes could be made for the space elevator, damage from micrometeorites and even erosion by oxygen atoms would render them weak. It would seem that sci-fi will never be anything other than what it is: a fiction."

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448 comments

Damaged by Oxygen? (2, Interesting)

Anonymous Coward | more than 7 years ago | (#15413468)

What about using a thin layer of something (paint? plastic?) to protect against oxidation? Or would that add too much weight?

Re:Damaged by Oxygen? (1, Funny)

damian cosmas (853143) | more than 7 years ago | (#15413485)

Ozone is a more likely culprit than dioxygen, so once we pollute the ozone layer out of existance, then the space elevator should be no problem ;)

Another way? (2, Insightful)

MikeFM (12491) | more than 7 years ago | (#15413788)

Are they seriously suggesting there is no way to make a space elevator or just not this way? I would think you get work out most of these kinds of issues by engineering better materials and by using something more redundant. If one cable isn't strong enough in the face of defects could they use say four that would each support the corner of an elevator? Could they make cables that would diagnose their own injuries and repair themselves? Every weakness is something that can be addressed and fixed.

Never? (4, Insightful)

brundlefly (189430) | more than 7 years ago | (#15413477)

It would seem that sci-fi will never be anything other than what it is: a fiction.

Never? That's a very, very long time. I would never bet against never. Never always wins. (Especially if you believe in an infinite universe.)

Re:Never? (5, Insightful)

nfarrell (127850) | more than 7 years ago | (#15413544)

There is plenty we don't know and many breakthroughs left in the universe, but I think it's human arrogance to think we're capable of omnipotence.

Sure, carbon nanotubes are neat, and gave us the impression we could build stronger structures and materials than previously. But why does their existance mean we're sure to find something equally strong AND able to withstand being a space elevator cable?

Don't get me wrong - saying 'never' is unwise, but it's almost as bad to assume humanity will be capable of everything one day.

Re:Never? (2, Funny)

dubonbacon (866462) | more than 7 years ago | (#15413568)

Especially if you believe in an infinite universe Then it may already have happened!

Re:Never? (1)

dubonbacon (866462) | more than 7 years ago | (#15413595)

I meant ... then it HAS already happened!

Re:Never? (0)

Anonymous Coward | more than 7 years ago | (#15413657)

I meant ... then it HAS already happened!

Why? Even if we propose that reality is infinitely old, composed at the bare minimum of a sequence of successive universes, it certainly does not follow that everything conceivable has happened or will happen. It is perfectly plausible that there are some things which are simply impossible.

Consider pi. Pi is infinite and varied. But if you write it out in base-10, you will never find anything other than the digits 0-9 (and one decimal point), because the base-10 representation of pi simply has those constraints. You cannot meaningfully say "maybe somewhere in pi, billions of billions of digits in, there is a little picture of an octopus instead of a digit, and because pi is infinite we can never know".

It is possible - perhaps even likely - that some of the laws we observe in our universe are just as fixed and fundamental as the laws of mathematics. Hence, it is quite conceivable that a space elevator might, in fact, be literally impossible to create with any material that can exist in reality. (And that's leaving aside the obvious fact that even if it's possible, there is no reason to suppose that any other intelligent life-form we might assume exists or has existed has discovered a method of building one.)

Re:Never? (0)

Anonymous Coward | more than 7 years ago | (#15413708)

You're missing the point of an infinite universe. You're merely thinking "very, very large". Infinite means just that. Every possible event has already happened, is currently happening, and will happen again. Infinitely many times. Possible events include a person walking through a wall. It's possible, just incredibly unlikely. But a very small chance, times infinite trials, means that it has already happened, is happening, and will again.

Re:Never? (5, Insightful)

soupdevil (587476) | more than 7 years ago | (#15413603)

An infinite universe is no guarantee that everything will happen. There are many infinities. For example, there are an infinite number of numbers between three and four, but none of them are five.

Re:Never? (1)

dubonbacon (866462) | more than 7 years ago | (#15413727)

IANAM (I am not a mathematician) You're probably right. Even if we take out the time factor, I guess the set of possible relative positionning of particules(or basic elements) in the universe is infinite uncountable [wikipedia.org]. The distance between them can be expressed as a real number so the diagonal argument applies.

Re:Never? (3, Informative)

Dire Bonobo (812883) | more than 7 years ago | (#15413785)

> I guess the set of possible relative positionning of particules(or basic elements) in the universe is infinite uncountable.

Not necessarily - Planck length [wikipedia.org] may be a minimum [blogspot.com] unit of distance in the universe, making the set of possible states potentially not merely countable but (along with the other Planck units) finite.

Crap (5, Funny)

dfn5 (524972) | more than 7 years ago | (#15413740)

For example, there are an infinite number of numbers between three and four, but none of them are five.
Crap. You just made my cat disappear. Thanks alot.

Re:Never? (1)

atrocious cowpat (850512) | more than 7 years ago | (#15413764)

"... there are an infinite number of numbers between three and four, but none of them are five."
Maybe in your puny little universe!

Re:Never? (1)

TheWanderingHermit (513872) | more than 7 years ago | (#15413655)

My thought was not just about betting against never, but that the companies involved in this have millions of dollars at stake. I'm sure they've studied the issue from every angle they can think of. If I were them, and had checked this out thoroughly enough to feel safe making a huge investment (or asking for one) in it, I'd have already gone through every scenario any of my people could think of.

Which means I'm sure the author is writing with research backing him up, but it is one voice of question compared to many who believe it can be done, and done in the next 15 years. If he were willing to put as much as stake that it can't be done as those who have put a stake in doing it, I might give the article some weight, but as it is, it's just one article and one dissenting view. Unless we see a lot of scientists agreeing, I'll still consider it possible until someone proves it impossible.

And then, as you said, he's betting against never.

Now Is Never (2, Insightful)

umbrellasd (876984) | more than 7 years ago | (#15413777)

The objections in the article will not hold for long. The real problem with this man-made structure as with most is that it is not self-repairing. That's the genius of the genetic code in our bodies. Out of necessity we have evolved repair mechanisms to cope with destructive interactions with our environment.

When we better understand genetics and what it takes to build self-sustaining repair subsystems, we will be able to build sustainable structures that exist in our atmosphere and beyond it. It's the same with our space stations and our space vehicles. They have an expiration date that is inevitable based on chance encounter with destructive environmental agents. The Earth is a self repairing structure that has been alive for billions of years. The Moon has been up there quite a while, too, and it's connected to the Earth by gravity. If we find a way to ride that link, we may well have the elevator we need already there.

But as far as coping with environmental damage, we have the same issues on earth with just about every object we create. It wears out and it wears out pretty rapidly. Even we wear out, though our repair systems allow us to do quite a few amazing things over a long period of time before we die. If we really want renewable structures, then they will have to have a "nervous system" of sorts that perceives structural damage and a "repair system" of sorts that can restore damaged areas to original state.

This is not impossible. Our bodies are proof that it is possible. We just don't know how to do it yet. Likely because it's never been a big enough priority. When we start to use up all the easily accessible non-renewable material resources on the planet, we may start making breakthroughs in this area of recycling and repairing rather than discarding (a la "cars no longer go to the junkyard because it's too costly to waste all those materials, so instead we build cars that can repair themselves and last 3 times longer (at which point we'll probably call them "horses").

Never isn't quite now, but it's not far.

...and in other obvious news... (0, Funny)

Anonymous Coward | more than 7 years ago | (#15413480)

Warp Drives do not yet exist!!!

I think the engineers can work this out. (1)

AltGrendel (175092) | more than 7 years ago | (#15413483)

Right after they're done perfecting the flying car.

Re:I think the engineers can work this out. (1)

LordLucless (582312) | more than 7 years ago | (#15413678)

Perfecting the flying car isn't too hard. Perfecting the average driver, now that's a tough one.

Re:I think the engineers can work this out. (0)

Krach42 (227798) | more than 7 years ago | (#15413695)

In Soviet Russia, flying cars want you!

*sigh* sorry :( I'll take the Karma hit.

Maybe in the tuture (1)

elgee (308600) | more than 7 years ago | (#15413486)

The technology is very young. Give it enough time and it MAY come to fruition. But in the end, it does seem very scifi.

Wireless Elevators (5, Funny)

9mm Censor (705379) | more than 7 years ago | (#15413489)

Just have 2 stations. One on earth, one in orbit. In between the two would be nothing but space.

Have the station on earth "launch" the "elevator" and the station in space "catch" it.

Re:Wireless Elevators (3, Informative)

AHumbleOpinion (546848) | more than 7 years ago | (#15413533)

Just have 2 stations. One on earth, one in orbit. In between the two would be nothing but space. Have the station on earth "launch" the "elevator" and the station in space "catch" it.

The acceleration would kill you. That's the nice thing about the elevator, it could be a very mild ride.

Re:Wireless Elevators (1)

susano_otter (123650) | more than 7 years ago | (#15413581)

The International Space Station "catches" containers full of people all the time.

So far, none of them have died from the acceleration.

In fact, in the entire history of "stations on the ground launching elevators that are caught by stations in space", dating all the way back to the first proof-of-concept Gemini missions, nobody has ever died from the acceleration.

Re:Wireless Elevators (3, Insightful)

cnettel (836611) | more than 7 years ago | (#15413598)

True, but both the space elevator approach and the approach of an almost immediate impulse launch (versus a conventional rocket) would be that we don't have to lift the fuel. The elevator has the added benefit of a possible counter-balance, but the main point is still that all current rockets use lots of fuel to lift other fuel.

This would naturally also make any kind of "power beaming" technology interesting, even if it would be quite inefficient, as long as it could be transformed into significant thrust easily in the receiver.

Re:Wireless Elevators (3, Interesting)

PieSquared (867490) | more than 7 years ago | (#15413650)

There is a slight difference with that: the acceleration takes place over the entire flight to orbit, not entirely on the ground. Instead of having a steady acceleration of at most a few G's, a station based on the ground "throwing" an object strait up would have all the acceleration before it left the structure, probably killing everything alive on board. Coming back down isn't so bad as you have a terminal velocity, and acceleration is limited to gravity, only 1 G. The only way a ground based structure could do a "throw" would be if the "throw" were not strait up, but rather at an angle very shallow to the earth's surface, giving the acceleration on a track over miles. The problem with that of course is that the total air resistance while leaving earth is far greater, meaning even more, instead of less, energy. No, overall if you want a steady non-rocket based acceleration into space, the space elevator is *still* more viable.

Re:Wireless Elevators (1)

MrSquirrel (976630) | more than 7 years ago | (#15413712)

The most viable option is something I got the idea for while at the mall... space escalators! There would be a stripe down the middle to seperate the "just stand there" side from the "I'm in a hurry so I'm walkin' up this thing" side. Now... If only I could figure out a way to make humans breathe in space. In all seriousness -- a space elevator IS possible. The article just says that it has the possibility of becoming damaged really easily... well, wikipedia states "Modern rocketry gives prices that are on the order of thousands of U.S. dollars per kilogram for transfer to low earth orbit, and roughly twenty thousand dollars per kilogram for transfer to geosynchronous orbit. For a space elevator, the price could be on the order of a few hundred dollars per kilogram, or possibly much less." As long as it is cheaper to build (or 'repair') the space elevator vs. a rocket-based space system, the idea remains appealing. Using algebra, $20,000/kg divided by $500/kg = 40. So given that rough approximation, it would be economically viable for quite a few repairs/new space elevators. ...now all we have to do is get the technology behind it to work.

Re:Wireless Elevators (1)

rho (6063) | more than 7 years ago | (#15413683)

You mean, "why don't we use rockets to get things into outer space"? Because it's expensive per pound of cargo. That's why.

Unless you're being humorous.

History repeating itself (2, Interesting)

webmistressrachel (903577) | more than 7 years ago | (#15413490)

As usual, with groundbreaking theories and inventions, we will deny it's possibility even after (if) we see it's work. But sooner or later, it may be viable, and soon acceptance and common use will follow.

Do I need to give any examples? Telescopes, electricity and magnetism, etc etc...

All too familiar (1)

brian0918 (638904) | more than 7 years ago | (#15413563)

"As usual, with groundbreaking theories and inventions, we will deny it's possibility even after (if) we see it's work.

Do I need to give any examples?"


No, we all remember what it was like before color was invented. Imagine Judy Garland's chagrin in realizing she spent 6 months skipping along a red brick road. Of course, with the wonders of technicolor, they were able to disguise that fatal flaw.

And don't even get me started reminiscing about the time before gravity was invented.

Re:All too familiar (1)

deathy_epl+ccs (896747) | more than 7 years ago | (#15413675)

And don't even get me started reminiscing about the time before gravity was invented.

Propagation of the species was even more fun back then, though...

Re:History repeating itself (0)

Anonymous Coward | more than 7 years ago | (#15413571)


Do I need to give any examples? Telescopes, electricity and magnetism, etc etc...


Not to mention time travel, warp drive and light sabers

Re:History repeating itself (0, Troll)

exp(pi*sqrt(163)) (613870) | more than 7 years ago | (#15413767)

As usual, with groundbreaking theories and inventions, we will deny it's possibility even after (if) we see it's work. Can you tell me where you saw the working space elevator whose existence you imply?

Never is a heck of a long time (0, Offtopic)

WillAffleckUW (858324) | more than 7 years ago | (#15413491)

And people seem to forget that carbon nanotubes were fiction less than two decades ago.

Now, if you said "not within a decade", that I might believe.

But in my world (biochem, nanotech, biotech, pharmacom, medical genetics, proteomics) we totally change the world every five to ten years, finding our former understanding isn't a fraction of the actual reality, so I wouldn't be that pessimistic.

I'd be far more concerned with the terrorist threat potential to space elevators than to the component aspect.

And in other news... (0, Redundant)

eimikion (973712) | more than 7 years ago | (#15413492)

Paris in the year 2000 will be covered by two meter high horse crap.
Futurology is very risky business. Prophecies about the state of possible future technologies based on contemporary knowledge are usually not much worth, in best cases, and utmost crap in the worst ones.

Hello editors (1)

arodland (127775) | more than 7 years ago | (#15413493)

If you refuse to edit incoherent rambling submissions, at least have the decency to refrain from posting them.

Successful Test?!? (5, Insightful)

Tackhead (54550) | more than 7 years ago | (#15413496)

> Three months ago, the dreams of a space elevator finally seemed to be coming true after a successful test. An article in Nature, however, suggests that there's reason to be pessimistic.

Reason #0 to be pessimistic: A "successful test" isn't a climbing robot. The climbing robot isn't the hard part of the problem. The hard part of the problem is the materials science.

Nor is it the sort of discoveries we've seen in the materials side of the equation; fibers measured in millimeters. That's not a prototype, it's just basic research. Interesting basic research, worthy basic research, and good basic research to be sure, but it's not a demonstration of practicality by any stretch of the imagination.

When someone builds a small footbridge out of these things, I'll be interested. When you can scale that to a mile-long suspension bridge that supports two lanes of traffic in each direction, I'll be optimistic.

Re:Successful Test?!? (2, Insightful)

Chris Burke (6130) | more than 7 years ago | (#15413772)

The hard part of the problem is the materials science.

Nor is it the sort of discoveries we've seen in the materials side of the equation; fibers measured in millimeters. That's not a prototype, it's just basic research. Interesting basic research, worthy basic research, and good basic research to be sure, but it's not a demonstration of practicality by any stretch of the imagination.

When someone builds a small footbridge out of these things, I'll be interested. When you can scale that to a mile-long suspension bridge that supports two lanes of traffic in each direction, I'll be optimistic.


Can't say I agree. The hard part of the problem is the materials science... and here we have in labs macroscopic fibers of a suitable material. Is it long enough? No. Is it strong enough? No. But neither were the first cables of drawn steel strong enough to do what we use them for today in applications you would consider uterly common. Like suspension briges.

The material science, the hard part of the problem as you say, is progressing fantastically. Not "operational space elevator in twenty years" fantastically, but we've made orders of magnitude improvements in strength/weight that were unfathomable twenty years before. I'd say there's every reason in the world to be optimistic, until further research shows that we are in fact heading down an impossible path.

At the point at which we've built a suspension bridge out of carbon nano-fibres, you're way past the point where anyone with any sense would be optimistic. Assuming we've solved the other problems that now seem inconsequential, like climbing robots, then building the elevator would simply be a matter of dedication of resources. Much like building the first steel suspension bridge after the development of sufficiently good steel wire.

Never say never (3, Insightful)

LiquidCoooled (634315) | more than 7 years ago | (#15413504)

We consider ourselves masters of our universe, however there is so much yet to learn.

It always amazes me how a spider can weave a thread which is so strong and flexible yet for all our mastery of the earth we cannot yet reproduce its properties.

I believe we will find a pathway to the stars, whether it is a single tether or an entire webbed tower I don't know but I am not ready to give up on mans' inginuity.

Re:Never say never (2, Informative)

SteveAstro (209000) | more than 7 years ago | (#15413573)

Spider silk has been synthesised, and there are genetically modified goats that secret spider silk proteins in their milk. Strength to weight wise, spider silk is comparable to Kevlar.
http://www.isracast.com/tech_news/271204_tech.htm [isracast.com]

Steve

Re:Never say never (1)

LiquidCoooled (634315) | more than 7 years ago | (#15413782)

Read the article you quote carefully.
There is snake oil present in there.

I quote:


These fibers were identical in their diameter to that of real spider fiber and were found to be equal to, and in certain aspects even exceeded, the chemical resistance quality of the spider-created fiber.


Now, you are right, they have done lots, but they are not yet there because nowhere in that article does it say we can create fibres of the strength of a spiders dragline.

Chemical resistance != tensile strength, but the words have been chosen carefully.

Asteroids? (1)

thealsir (927362) | more than 7 years ago | (#15413507)

Meteorites? Space junk? Other large flying objects? It would seem that a force field technology would be necessary in order for a space elevator to be viable without being knocked out of orbit or broken after a few months. That and the micro/macro defects in the tubes. What if the base detaches from the ground? Such a device's acceleration toward earth would be very difficult to stop with ordinary thruster motors.

Re:Asteroids? (1)

AHumbleOpinion (546848) | more than 7 years ago | (#15413580)

What if the base detaches from the ground? Such a device's acceleration toward earth would be very difficult to stop with ordinary thruster motors.

I believe the acceleration of the cable and car would be away from the earth, regardless of the car's original mode of ascent or descent.

Re:Asteroids? (1)

thealsir (927362) | more than 7 years ago | (#15413589)

Yeah, I meant to say what if there was an impact sending the upper part of the station speeding toward earth?

Re:Asteroids? (1)

Jeremi (14640) | more than 7 years ago | (#15413735)

What if the base detaches from the ground? Such a device's acceleration toward earth would be very difficult to stop with ordinary thruster motors.


If the base were to detach from the ground it would accelerate away from the Earth, not toward it.


That said, the base wouldn't detach from the ground. The ribbon would break long before there was enough force to lift the base from its foundations.

That is a pretty sweeping statement (1)

tempestdata (457317) | more than 7 years ago | (#15413510)

I would agree with the poster, if he/she had ended that statement with ".. in the foreseeable future", but he/she didn't, and I think he/she will most likely be proven wrong. The Article however, I cannot disagree with. The article states "Carbon nano tubes cables wont hold up", which may or may not be accurate, but it doesn't make sweeping statements about the future like the poster does.

Why is it that you preclude the possibility of finding substances stronger than nanotubes? Even if the laws of phsyics would state "you cant get stronger than a nanotube", I would still be sceptical. What we call the laws of physics, aren't really laws.. they are formulations and theories based on observation and experimentation, that have withstood rigorous testing and are generally accepted.

However, as our understanding of the universe grows, those laws might change too :)

Psha! (3, Insightful)

rechelon (719515) | more than 7 years ago | (#15413511)

I thought the whole point was to be constantly rebuilding the 'string' (ie running repair bots up and down the structure or finding other repairing methods). This doesn't prove that space elevators are impossible. It just means we'd need to make a few more tech advances.

Which is, of course, always the case. But the starry-eyed folk have always known they'd have to engineer some constant repairing mechanism. I just don't see how this is a big deal.

Re:Psha! (0)

Anonymous Coward | more than 7 years ago | (#15413602)

aggreed...

constant repair bots can fix it.
or if they are hard to repair, then bots could be perpetually bringing up new nanotube filements.

Was it not the plan to use the first space elevator to build the second in a fraction of the time (and for a fraction of the money)?

unwarrented negativism (4, Insightful)

phantomfive (622387) | more than 7 years ago | (#15413512)

OK, the summary is ridiculous here. It assumes that because one method of making a space elevator might be impossible, that it can't be done, ever in any way.

There is so much that we don't know about the physical universe, that to even say we are beginning to understand what is possible is silly. Faster than light travel? Possible or not? As far as we have observed, not. Does that mean it's impossible? NO! We aren't even sure what time/space is, how can we say what is and isn't impossible? Is a space elevator impossible, just because this one method might be impractical? NO!

Somehow I wonder if the submitter was just trying to sound sensationalistic to make sure his story got accepted. And I just fell in his trap. Oh well. He did seem rather gleeful about the whole thing, though.

One way to find out (2, Interesting)

spineboy (22918) | more than 7 years ago | (#15413514)

Just do it - or at least a small model. After all these critics are in the same family that once said

Humans can't fly

Humans can't survive going more than 100 MPH

Can't transplant a heart
Maybe just a simple plastic coating will protect it. Saying something can't be done should mean nothing to most people.

Re:One way to find out (1)

Jack9 (11421) | more than 7 years ago | (#15413706)

The strongest argument against it, is that we haven't solved simpler CRITICAL social, biological, and mechanical problems. Why support this? It deserves derision.

Let's Not Pull the Plug Yet (1)

runningoutofnickname (852952) | more than 7 years ago | (#15413519)

I wouldn't rush to conclude that the space elevator will never be realized. If it does take longer than initially anticipated, so be it. I would encourage LiftPort to continue its work; at the rate the space program moves (in fits and starts), perhaps a space elevator might eventually be a more economical way to lift material out of Earth's gravity well anyhow. I wouldn't want people fifty years in the future to look back and think, "Gee. The Shuttle has been scrapped. The CEV program didn't work out. IF only we had continued working on the Space Elevator, we would have an operating elevator at this time (rather than nothing at all)."

Is that the only problem? (4, Interesting)

irexe (567524) | more than 7 years ago | (#15413527)

Sorry for being slightly off topic, but as a non physicist, I've always wondered why the other seemingly obvious problems with such a device are never really considered problems. I am thinking of storm type winds blowing it off balance or making it resonate, the danger to aeroplanes, the disastrous consequences of breakage, etc. Why aren't these problems?

Re:Is that the only problem? (1)

Shrithe (972491) | more than 7 years ago | (#15413560)

if it breaks, points above the halfway mark fall fall upwards. Don't think of it as starting at the ground and going up. It's more accurate to think of it as starting in space and hanging down. Storms would only affect a small portion of it, although resonance is a serious issue and one that it is carefully considered. Planes would route around it, like they do any suitably tall structure. Satelites and orbiting debris is also a consideration, but those are well mapped and regular: the elevator would be controlled to move around them as need be.

Re:Is that the only problem? (2, Interesting)

scdeimos (632778) | more than 7 years ago | (#15413680)

if it breaks, points above the halfway mark fall fall upwards.
That's not actually correct. The entire ribbon is under tension due to the centrifugal force imparted on it by the counterweight (the station in space), so all of the ribbon above the break will "fall up" even if the break is only six feet above the sea level. I'd hate to be on the station if that occurs - you'd get flung out into space beyond reach any sort of timely rescue.

Re:Is that the only problem? (2, Informative)

Jeremi (14640) | more than 7 years ago | (#15413570)

I am thinking of storm type winds blowing it off balance or making it resonate, the danger to aeroplanes, the disastrous consequences of breakage, etc. Why aren't these problems?


The considerations you listed aren't considered problems because there are fairly obvious solutions for each of them:

  1. Locate the elevator in an area where storms don't occur
  2. Locate the elevator in a no-fly zone, well away from flight paths
  3. Design the elevator as a ribbon with a very low terminal velocity (think falling like newspaper, not falling like bricks), so that breakage doesn't cause any damage (outside of losing the ribbon itself, of course)


For more information on the engineering involved in building a space elevator, check out this book [amazon.com] -- it goes into detailed explanations about your objections, as well as many others.


In short, there are big problems to be solved before you can build a space elevator, but those aren't them.

Re:Is that the only problem? (1)

IntlHarvester (11985) | more than 7 years ago | (#15413797)

Sorry for being slightly off topic, but a non-scifi-fan, wouldn't commercially-viable nanotubes have many many more obvious applications than a "space elevator"?

It seems to me that if we had these things, society would spend decades building taller buildings, longer bridgers. lightweight automobiles and so on. And after all that, then maybe it would be feasible to build a space elevator.

It just seems that the advocates of this thing are trying to "shoot the moon" (parden), when perhaps if they weren't so startreky about the application, there would be much more commercial R&D.

Impossible (3, Insightful)

eric.t.f.bat (102290) | more than 7 years ago | (#15413528)

Even if it were possible to operate such a large collection of vacuum tubes with the small power supplies available for household electrical equipment, the glass fabrication process has too many flaws to enable mass production on such a scale. It would seem that the "personal computer" will never be anything other than what it is: a fiction.

Re:Impossible (1, Interesting)

Anonymous Coward | more than 7 years ago | (#15413691)

And even if we could somehow have mass production on such a large scale the failure rate of the tubes means there is a finite size for the computator mechanical mind before the probability of a tube blowing every minute rises to 1 and so they become unsuable. "everything that can be invented has been invented" - yeah right.

Man will never fly. (1)

Hershmire (41460) | more than 7 years ago | (#15413550)

"Three hundred years ago, the dreams of a flying machine finally seemed to be coming true after a successful test. An article in Nature, however, suggests that there's reason to be pessimistic. Ever since Bernoulli's principle was discovered, many have been hoping that this discovery would turn the dream into reality. Pugno, however, argues that inevitable lack of pure steel means that such a machine simply wouldn't be strong enough. Even if flawless steel could be made for the flying machine, damage from wind and even erosion by sand would render it's wings weak. It would seem that sci-fi will never be anything other than what it is: a fiction."

Constant renewal... (1)

RyanFenton (230700) | more than 7 years ago | (#15413555)

Certainly, sections will give way over time if left alone. I thought the very idea of starting a space elevator was first to get a small number of strands, from which more could be threaded up, using existing threads, until you had an appropriate ribbon.

Can the ribbon be built in a way that the failure of a set of threads doesn't automatically bring greater burden onto nearby threads, but instead allows for the failure to be detected and compensated for, perhaps with a second ribbon or else have the payload parachute back downward with minimal guidance by the ribbon?

Just the random guesses of a layman.

Lunar Space Elevator (2, Interesting)

randall_burns (108052) | more than 7 years ago | (#15413584)

What puzzles me is why there hasn't been a bigger push for creation of a Lunar Space Elevator [wikipedia.org]. A lunar space elevator could be built with existing materials--though the launch costs would be significant. We'd learn a lot from this kind of practical project--and raw getting materials into orbit for a variety of purposes would get much less expensive.

Re:Lunar Space Elevator (2, Funny)

rho (6063) | more than 7 years ago | (#15413702)

Because it costs a lot to go to the moon? Did you think through your question? At all?

Science at its best! (1)

bunbuntheminilop (935594) | more than 7 years ago | (#15413587)

"For there is no comparison between that which we may lose by not trying and by not succeeding; since by not trying we throw away the chance of an immense good, by not succeeding we only incur the loss of a little human labour"

Francis Bacon - Materialist-philosopher

Re:Science at its best! (1)

susano_otter (123650) | more than 7 years ago | (#15413617)

by not succeeding we only incur the loss of a little human labour

Heh.

One of the big controversies of our time seems to be how little our society values the labor of others.

It's very easy for a philosopher to say, "enh, so what if we fail--after all, it's not like I'm the one doing all that hard work, all for nothing".

The spirit of mankind (1)

Space cowboy (13680) | more than 7 years ago | (#15413599)

What I think is interesting in this forum is the general upbeat attitude - that's what will make this even a possibility at some indeterminate time in the future. The basic assumption is that "sure, we can't do it now, but maybe someday. And what about *this* as an idea". Until that optimism dies, there is always a chance we'll find a way.

Materials science is *not* fully known, or even nearly so. One of the most simple compounds on this planet (H2O) has all sorts of weird and wonderful properties - new discoveries about it made the cover of "New Scientist" in the UK a few months ago. This is *water* we're talking about! It's not even organic chemistry! Who knows what a molybdenum/aluminium/carbon alloy made at *this* pressure and temperature might do...

I say let the dreamers dream, let the scientists work, and the science-fiction writers come up with challenges for the scientists. To say "never" is hubris of the highest order...

Simon

Bah. You could make it out of steel cable. (1)

jhesse (138516) | more than 7 years ago | (#15413614)

No. Really.

For the homework of one of my astrophysics classes, we calcuated that you could, if the cable was not the same thickness along it's entire length.

For steel cable, it had to be 162 (IIRC) times thicker at the point of highest tension than at the bottom. Minimum(no load).

Or something like that.

Re:Bah. You could make it out of steel cable. (1)

Chris Burke (6130) | more than 7 years ago | (#15413795)

The proposals I've seen using nanotubes have had a tapered cable or ribbon. I certainly couldn't disprove it, but I'd be surprised to find that steel would actually work.

self healing (1)

teknikl (539522) | more than 7 years ago | (#15413619)

so you make the elevator with self-healing nanotubes - a long machine really. big deal, so this just takes longer.

How about Tethers and Rotovators instead? (2, Interesting)

DumbSwede (521261) | more than 7 years ago | (#15413621)

Why this obsession with a full blown "Space Elevator" when there is so much that can be done in the interim with tethers? Rotavators [wikipedia.org] would require significantly less demanding materials and only require getting above atmosphere like SpaceShip One did recently. Then clamp on and ride the rest of the way to full orbital velocity (the tip would appear to hover briefly in sync with the Earth's rotation just above the atmosphere).

No nanotubes tested yet (1)

scdeimos (632778) | more than 7 years ago | (#15413622)

Folks, it's worth noting that tests to date have only been on the robot climbing systems themselves, using two inch wide composite fibreglass ribbons and not carbon nanotube ribbons. eg: [msn.com]

This week's testing involved a 12-foot (4-meter) diameter balloon. Safety lines held by team members kept the balloon from floating away. The ribbon dangling from the balloon was made of composite fiberglass, with the robot lifter running up and down the tether.

I expect that they'll eventually hit the 62GPa strength requirements for the metre-wide nanotube ribbons, but I'm not expecting that within the three years that Edwards is predicting.

Eh, this has been said before. (1)

RsG (809189) | more than 7 years ago | (#15413630)

Every time I see the idea brought up that X technology is either right around the corner, or will never happen, I take a step back and remember just how bad we humans are at seeing the future.

Remember when 2000 was going to be the year we had flying cars, moon bases and nuclear power in our homes? And how would someone making those same wild predictions have reacted to the idea of home computers? We vastly overestimated what we could do in one area, and underestimated the other. Whether this was predestined due to feasability, or whether it was a question of where we spent our research dollars, is a something I've always wondered...

Anyway, the way I've always looked at it, a new technology has several stages it must pass before we can make any assumptions about it. Each stage we get past (or get stuck at) gives us a better picture of what the future holds:

1. Does the proposed idea work within the laws of physics as we currently understand them? This is the level that perpetual motion will forever be stuck at (pardon the pun). This is also where any dreams of FTL travel and generated gravity go - they shall remain fictional unless physics opens up the possibility in in future. We can make no predictions here, other than sometimes saying "that will never work".

2. Does the technological advance require other advances first? Anything that requires fusion power, or any sort of "unobtainium" type materials, or advanced biotech, goes here. This is where the space elevator is currently stuck (another pun... ), since we can't yet produce the materials we need. Generally, anything in this category is possible, but may or may not transpire in the future - there's no way to predict either way.

3. Do we have the engineering know-how to make this work? This is often just a matter of time. Fusion power, reusable lauch vehicals and ion engines go here. I'd call this the "beta", since it's generally the stage where we are building prototypes and getting there in small steps, often with setbacks. It takes time and testing to advance out of this stage, just like in a software beta.

4. What are the practical, political, ethical, and other issues with this technology? See the hydrogen economy as an example of practical problems (ie, where do we get the energy we'd need) and human cloning as an example of an ethical problem (do we really want to do this with a human being?) Both are naturally political issues as well.

How well predictions work depends on where we are. We cannot predict the first category (except when something truely is impossible), we can rarely predict the second, we can sometimes project trends accurately enough in the third, and for the fourth one the question is often if we will, not when we can. Given where the space elevator is at the moment - a workable idea hinged on large quantities of unobtainium - I'd say we can neither predict when nor if it will happen.

Liftport already responded to this (5, Informative)

Shrithe (972491) | more than 7 years ago | (#15413635)

This has already been addressed by Liftport, [liftport.com] the company actually doing the work here:

I've discussed the article with a couple of CNT researchers, and they say that they're not convinced by the paper. My attitude is that we have to wait and see what really happens, because there's a lot about carbon nanotubes that we don't know yet.

Despite anyone's predictions, we won't know what the material will be like until it's made. There's a LOT of other work that needs to be done on SE development regardless of what the material winds up being. And in the "worst" case, you can still build a space elevator on the moon with near-term materials.

One thing to remember is that, even if bulk CNT were limited to 30 GPa, we could still build the space elevator. It would just become limited by finances. That's because, with a density of 1300kg/m^3 and a strength of 30GPa, the mass of a seed ribbon (using the same assumptions as in my November article - safety factor of 2, and 1,000kg capacity) would be roughly 3,440 tonnes (i.e., 3.44*10^6 kg), or roughly 170 rocket launches (using current medium-lift rockets) to loft it (i.e., ~80 times as massive as in the 2002 NIAC report). The expense and logistics of creating a seed ribbon at that point (assuming you're launching from Earth) becomes much more daunting, but not impossible.


and for people raising other concerns, which I see in several places here:

Breaking is a minor issue. Most of it would fall up. The base station doesn't support the elevator, it holds it down. The Earth's rotation keeps it up. People tend to forget the scale we're dealing with here. The bits that fall down would burn up, land as ash.

Space debris is well mapped. We can avoid it, for the most part. Small adjustments made from either end of the elevator can be used to shift the bulk of the thing. Remember, serious plans for it call for building it on a floating platform, which can move, and rockets can be used to adjust the space end of things.

Storms, well, like I said, we can move the thing. Also bear in mind that storms only affect the part of it in the lower atmosphere. Resonance is an issue which is being seriously considered, as well as induced current.

Any more problems you'd like to raise? Read the wikipedia article [wikipedia.org].

Still feasible in other places. (2, Interesting)

thisissilly (676875) | more than 7 years ago | (#15413641)

For Earth, perhaps. But for Mars and Luna, space elevators could still be built. In fact, a Lunar elevator could be built out of Kevlar, without the need for carbon nanotubes.

Bridges made out of metal?... (0)

Anonymous Coward | more than 7 years ago | (#15413645)

Bridges made out of metal? Preposterous!! Why, metal rusts when exposed to air and water. And what do you think rain is??? Won't work, I tell you! Impossible!

1000 years is a long time ..... (1)

WhiteWolf666 (145211) | more than 7 years ago | (#15413664)

The current "visionaries" planning a space elevator are no different than the early flying machine designs of the enlightenment.

Da Vinci dreamed of flying. Tesla dreamed of flying without wings. All kinds of scientists dream of the future.

That doesn't meant that when the dreams come to fruition they have anything but a passing resembalance to past visions. A space elevator will probably not be constructed of carbon nanotubes, at least not of the variety we are currently playing with. Nor will it be "staffed" by climbing robots, at least not of the variety we can currently build.

I don't know anything about materials science, but I wouldn't be surprised to see us develop something that could be artifically strengthed via electromagnetism, or something else. Gotta keep it juiced up or something.

I believe the best way to characterize the article is, "Carbon nanotubes are most likely not sufficent for space elevator construction," rather than, "Space Elevator an Impossible Dream?"

The Space Elevator was an Impossible Dream before carbon nanotubes, too. That doesn't mean we give up looking for a suitable tether material, nor do we give up looking for elegant paths around the limitations in tether strength.

At Last (1)

PhysSurfer (872187) | more than 7 years ago | (#15413667)

At last people might start realizing what a money dump this whole project is.

The defect problem is just one of many problems in manufacturing the CNT ribbon (eg it could take millions [slashdot.org] of years to grow a continuous ribbon, weaving them together is just not strong enough).

Common sense would dictate that we stop spending so much money on this project immediately. Carbon Nanotubes have many other applications on the cutting edge of technology, notably in nanoelectronics and sensors, that are much closer to fruition. Just as in the semiconductor industry, once these technologies mature we should see vast improvements in the growth process. Then we could turn to the space elevator problem, presumably with some defect-free growth process already in hand.

As it is we're just pouring money into a money pit of a dream impossible with today's technology. Typical of our government... missle defense anyone?

Re:At Last (2, Insightful)

Jeremi (14640) | more than 7 years ago | (#15413765)

Then we could turn to the space elevator problem, presumably with some defect-free growth process already in hand.


What you propose is essentially what's being done. A small amount of money is being placed into theoretical research on Space Elevators, and that is what gets into the news because they are fun to think about, but the vast bulk of the money is (quite rightly) being spent on basic carbon nanotube materials research -- which is a good investment whether we end up building space elevators, or not.


As it is we're just pouring money into a money pit of a dream impossible with today's technology. Typical of our government... missle defense anyone?


Can you point to any actual figures about how much money is being wasted on research that has no application outside of Space Elevators? Or are you just assuming the worst, and bellyaching about the products of your imagination?

Oh wow. A problem... (1)

Conspiracy_Of_Doves (236787) | more than 7 years ago | (#15413674)

Oh well, lets just give up then. That's what inventors and scientists have always done, and thats how we got the technology-rich culture we have today.

Fiction? (1)

Killshot (724273) | more than 7 years ago | (#15413682)

Sci-fi will always be fiction eh?

Spaceflight, cloning, teleportation... all sci-fi.. none of that stuff has ever happened in reality.

There is nothing wrong with being pessemistic and pointing out flaws in a concept. In fact it is quite important.
But to say something will never work is silly.

Another fiction (0)

ThePhilips (752041) | more than 7 years ago | (#15413684)

In Peter Hamilton's [wikipedia.org] The Night's Dawn trilogy, Earth have had a kind of very high towers reaching out of Earth gravitation.

It's basicly elevator - but more like real one. That sounds less fictious than super strong wire. And honestly something humanity - if wanted - can do even now.

No imagination. (4, Funny)

AnotherBlackHat (265897) | more than 7 years ago | (#15413686)


Pugno, however, argues that inevitable defects in the nanotubes mean that such a cable simply wouldn't be strong enough.


Sheesh, what's wrong with these people?
If the current cable isn't strong enough, there are lots of possible solutions.

For example, the strength of the cable necessary is directly related to the mass of the earth.
One good sized metor at high enough velocity striking the earth, and we could build the elevator out of nylon rope.

Some other methods of reducing the mass of the earth are available here http://qntm.org/destroy [qntm.org]

-- Should you believe authority without question?

Of course Nature is right on... (1)

Polonius916 (977362) | more than 7 years ago | (#15413693)

How silly for people to think that Verne might not be smoking when he speculated that we'd land on the moon! What folly! And Clarke to think that there was a band of space where a MAN made object could stay directly above a location on earth. What a joke! And that the Earth isn't the center of the universe! And how about those fools who disagreed with the US patent office in the late 19th century when they tried to ban new patents because everything that would be invented had been! Of course we know everything. We are little gods, right? Burn anyone, everyone and anything that doesn't agree with our current understanding of the universe. Burn them I tell you!

FUD vs. Hype (1)

HiThere (15173) | more than 7 years ago | (#15413717)

The "Successful Experiment" was hype in so far as getting a Space Elevator built. It doesn't prove much, and it wasn't intended to. It was largely a PR exercise.

The FUD is basically saying "we don't know how to do it now, so it can't be done".

Both are silly, but the hype at least serves some legitimate purpose.

Erosion by oxygen atoms (0)

Anonymous Coward | more than 7 years ago | (#15413732)

Since buckytubes can contain other atoms, if they are worried about erosion by oxygen atoms, couldn't they put some concentration of fluorine (or some other element) inside the tubes to keep electrons preferentially bound? I'm not sure about ozone, but O2 isn't going to grab an electron from a fluorine atom.

If it gets damaged... (1)

bsantos (655278) | more than 7 years ago | (#15413746)

...just need to create self healing nano structures. Just like our bones repair themselves and adjust to impact.

Seen the self replicating bots, the self reconstructing chair, I see nothing impossible in the elevator, just a few techical issues to solve. :)

Time for an Orion! (1)

sudog (101964) | more than 7 years ago | (#15413754)

You want to travel to the stars? Do it right: build an Orion and just be done with it. A single, or even a dozen, Orion launches would push us out further to the outer reaches of the solar system faster and more completely than the way we're currently heading: little squirts of machinery and technology at carefully planned moments. Bah!

other problem? (1)

cecilgol (977329) | more than 7 years ago | (#15413760)

what would happen if a commercial airliner, or flock of seagulls, were to run into the cables, or even worse, the actual elevator? would the plane split into five pieces or would the cables snap and bring the satellite down on dallas? animal rights activists would have a fit.

Self-repairing materials not much more SciFi (1)

Saeger (456549) | more than 7 years ago | (#15413773)

Even if a space elevator made of static nanotube ribbon turns out to be impossible from a conventional maintenance perspective, that doesn't mean that this ideal method to get out of a gravity well is dead -- it would only mean we'd have to wait just a few more years of accelerating progress [kurzweilai.net] for full-blown nanotech to make active, self-repairing materials a reality.

Current "nanotech" is mostly just fancy materials science and top-down bulk-tech chemistry (with the nano buzzword thrown in to make getting funding easier). Bottom-up active nanotech & molecular manufacturing will make space elevators, and ever more "impossible" inventions, possible.

Impossible? (1, Informative)

Centurix (249778) | more than 7 years ago | (#15413778)

Patch the bad bits of nanotubes with duct tape. It's made from the fabric of space and time itself.

Oxygen!! What about lightning!? (1)

gwait (179005) | more than 7 years ago | (#15413798)

If they're worried about corrosion, what about a nice dose of lightning?

From this page:

http://www.ucar.edu/communications/infopack/lightn ing/faq.html [ucar.edu]

This extract:

Just before it reaches ground, the step leader induces a huge electric potential (some 10 million volts), enough to bring up surges of positive charge from sharp objects or irregularities near the ground. Once the impulses meet--a few tens of meters above earth--the connection is established and the return stroke zips upward at a rate much faster than the stepped leader's descent. It is this return stroke that produces the visible flash as it heats surrounding air to 30,000 degrees C (54,000 degrees F), which in turn creates the shock wave we hear as thunder.

I claim using a space elevator as a power generator, assuming it lasts long enough to plug in an extension cord...

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