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Space Elevator An Impossible Dream? 448

Posted by Zonk from the sniffle dept.
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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Space Elevator An Impossible Dream? More

Space Elevator An Impossible Dream?

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  • Damaged by Oxygen? (Score:2, Interesting)

    by Anonymous Coward
    What about using a thin layer of something (paint? plastic?) to protect against oxidation? Or would that add too much weight?
    • 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 ;)
    • They're too slippery to bond that kind of thing effectively:

      http://www.sciencedaily.com/releases/2005/11/05111 7114309.htm [sciencedaily.com]

    • Another way? (Score:3, Insightful)

      by MikeFM ( 12491 )
      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.

      • Re:Another way? (Score:3, Informative)

        by Rei ( 128717 )
        The problem is that CNTs *themselves* are defective with all know methods of manufacturing them. You'd need to have multiple levels of load transfer for every single nanotube. Of course, every branching weakens your tubes...

        Can we enhance current CNT methods to not produce any defects? Probably not. CNTs typically have irregular balls of carbon at the center or the ends because this is what they develop from. The strongest SWNT ever measured was, if I recall correctly, 61 GPa tensile strength. Way too

    • Re:Damaged by Oxygen? (Score:5, Informative)

      by TamCaP ( 900777 ) on Friday May 26, 2006 @08:12PM (#15413841)
      If I understood correctly ("oxygen atoms") the author was not refering to O2 nor O3 but simple free oxygen radicals. At high altitudes (ozone layer height and above) the UV radiation is strong enough to split O2 and O3 molecules into free radicals (homolytic cleavage). The product is represented in chemistry as O. (O with a dot). This is a relatively stable molecule, but very reactive. And I mean very. It will do anything to bind to something and get back to favourite 8 electrons in valence shell configuration.

      And as we are not really able to produce material that would be strong enough and light enough to support the space lift even in perfect conditions (there are really nice Internet-available articles and research papeers on this issue), producing a practical model is still much more thing of fiction, than of science. Therefore any coating or protection from whatever may be hazardous for our lift needs also to be developed and is a topic for the future. But may be in far future...

      Oh, and there was extensive research done on many different earth-to-orbit propulsion systems, some more possible than the others. My biggest enthusiasm got the nuclear-engine, but for obvious reasons research in this area is right now strongly inhibited (if there is any at all).

      • Re:Damaged by Oxygen? (Score:5, Informative)

        by damian cosmas ( 853143 ) on Friday May 26, 2006 @09:50PM (#15414158)
        You needn't go as far as free radicals, since Ozone by itself will react with the strained olefins in nanotubes, and is abundant in the upper atmosphere. Here [acs.org] is a computational paper on the matter, and here [acs.org] is an experimental follow-up. Then there's the problem of the increased UV radiation when you get higher, since your elevator is just one big chromophore.

  • Never? (Score:5, Insightful)

    by brundlefly ( 189430 ) on Friday May 26, 2006 @06:46PM (#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? (Score:5, Insightful)

      by nfarrell ( 127850 ) on Friday May 26, 2006 @06:59PM (#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? (Score:2, Funny)

      by dubonbacon ( 866462 )
      Especially if you believe in an infinite universe Then it may already have happened!

    • Re:Never? (Score:5, Insightful)

      by soupdevil ( 587476 ) on Friday May 26, 2006 @07:12PM (#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.

      • Crap (Score:5, Funny)

        by dfn5 ( 524972 ) on Friday May 26, 2006 @07:42PM (#15413740) Journal
        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? (Score:5, Funny)

        by kfg ( 145172 ) on Friday May 26, 2006 @08:40PM (#15413928)
        . . .there are an infinite number of numbers between three and four, but none of them are five.

        "You fool," said the mathematician. "Don't you know that if you can only move toward the girl half the distance each time you'll never reach her?"

        "Yes," replied the engineer. "But after awhile I'll get close enough."

        KFG
    • 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 compa

    • Now Is Never (Score:2, Insightful)

      by umbrellasd ( 876984 )
      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 th

      • Re:Now Is Never (Score:4, Insightful)

        by NoTheory ( 580275 ) on Friday May 26, 2006 @08:17PM (#15413865)
        what a meaningless (parent) post.

        Bridging the gap between computer science, robotics, molecular genetics, and biochemistry seems like a bizarre and convoluted route to addressing the problems stated in the article.

        First, modeling engineered devices on real world objects, even features of living objects, is not a new concept. Second, we're talking a fairly simple system, a big long ribbon, not a complicated self-regulating autonomous device. Nor is there any reason to make something that would need to be as fault tolerant and robust as possible more complex than it needs to be. So, self-reparing system may sound sexy, but if a simpler mechanism can be devised than inventing an entirely new class of devices and methodologies to fix the problem, that is rightly the domain of material sciences, i fail to see why we'd want to start spouting off ungrounded hype about inter-disciplinary science that at the moment is... to be kind, speculative.

        • Re:Now Is Never (Score:4, Interesting)

          by Andrew Kismet ( 955764 ) on Friday May 26, 2006 @08:41PM (#15413934)
          Imagine a spider on it's web; the web is torn at one point. The spider fixes it by producing more silk.

          Imagine a small robot, even a nanobot, space elevator cable, made of many strands of carbon nanotubes. Imagine a way to pull carbon out of air and repair the cable.

          A spider produces silk from the food and air it consumes; a nanobot could repair nanotubes in much the same way, by "breathing" carbon dioxide or pure carbon and doing repairs. Hell, it doesn't even need to MAKE carbon nanotubes, it could pick them up at "ground floor" and deliver them up the cable.

          A self-repair system. No need to invoke convoluted biology and DNA.

    • Re:Never? (Score:3, Funny)

      by telbij ( 465356 )
      It would seem that sci-fi will never be anything other than what it is: a fiction.

      Fuck! I guess we'll never make it into outer space. NEVER! *slams head into piano like sesame street musician guy*

    • The human genome analogy (Score:3, Interesting)

      by DrYak ( 748999 )

      That's a very, very long time.

      You're right, I think.

      It's like saying that the Human Genome will never be decoded in less than 50 to 75 years.

      That was probably true when the HuGo project started, given technologies available back then.
      But because the biggest effort was done by public Universities, freely sharing result, tremendous advances were made, and with it incredible advance in sequencing technology.
      In the end most of the work was done in 15 years, the last tiny bit being finished after 20 years.

      Accord

  • Right after they're done perfecting the flying car.

  • Wireless Elevators (Score:5, Funny)

    by 9mm Censor ( 705379 ) * on Friday May 26, 2006 @06:49PM (#15413489) Homepage
    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 (Score:5, Funny)

      by TheKidWho ( 705796 ) on Friday May 26, 2006 @06:56PM (#15413531)
      That's called a rocket.

    • Re:Wireless Elevators (Score:4, Informative)

      by AHumbleOpinion ( 546848 ) on Friday May 26, 2006 @06:57PM (#15413533) Homepage
      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.
      • 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 (Score:4, Insightful)

          by cnettel ( 836611 ) on Friday May 26, 2006 @07:11PM (#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.

        • 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
    • 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.

  • 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...

    • "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.

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

      What an incredibly overbroad statement. Theories are only considered 'groundbreaking' in retrospect. Phrenology, the aether, phlogiston and Rutherford's model of the atom are examples of theories that had their moment in the sun and were found to be inadequate. You can't use the initial scepticism that inventions or theories that later proved to be correct faced in support of your desire t

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

  • Successful Test?!? (Score:5, Insightful)

    by Tackhead ( 54550 ) on Friday May 26, 2006 @06:50PM (#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.

    • 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 suspens

    • Re:Successful Test?!? (Score:3, Interesting)

      by kiwi77 ( 957316 )
      Just because we can make fibres with enough tensile strength to withstand loads for this thing doesn't address the entire construction question. My understanding is that we only have FIBRES. They have to be joined in a matrix of something, and that matrix will not have enough shear to support the tensile strength of the fibres. In carbon fibre materials, for example, an epoxy resin is cured around the carbon fibre. The fibres, because of their orientation and strength make a very strong structure; mater

    • Economics (Score:3, Informative)

      by abb3w ( 696381 )
      When you can scale that to a mile-long suspension bridge that supports two lanes of traffic in each direction, I'll be optimistic.

      Of course, the only reason anyone would built such a bridge is as a prototype demonstration to scare up investors. The potential ROI for a space elevator is pretty spectacular, not so much for a bridge... and buckytube isn't cheap.

  • Never say never (Score:3, Insightful)

    by LiquidCoooled ( 634315 ) on Friday May 26, 2006 @06:50PM (#15413504) Homepage Journal
    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.

  • 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 w

  • Psha! (Score:3, Insightful)

    by rechelon ( 719515 ) on Friday May 26, 2006 @06:52PM (#15413511) Homepage
    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.

  • unwarrented negativism (Score:5, Insightful)

    by phantomfive ( 622387 ) on Friday May 26, 2006 @06:52PM (#15413512) Journal
    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.

    • Re:unwarrented negativism (Score:4, Insightful)

      by dbIII ( 701233 ) on Saturday May 27, 2006 @01:27AM (#15414732)
      Is a space elevator impossible, just because this one method might be impractical?
      I think the point of the article was that someone woke up and saw that it really is a hard problem that will take a vast amount of resources - and not the simple ribbon you drop from the sky than people outside of the physical sciences and engineering are thinking about. It's a very long way up - and then to keep it up the you need a counterweight and station keeping systems - plus the obvious of having a highly conductive material with an incredible potential difference from one end to the other (magnetic feild etc) if you are talking about carbon nanotubes. To get an idea of the scale of things of this elevator, consider building a railgun out of carbon nanotubes designed to accelerate something the size of the capsule that will be going up. Wrap it around the equator twice. Now stand it on it's end with some sort of living platform in the middle of it. That's your free standing beanstalk in the simplest form. Microwave or laser powered climbing robots may sound cool, but it's a nasty and expensive hack to keep the heavy stuff on the ground and rather bizzare when you have a very highly conductive material that can get power to motors a lot more easily than an incredibly lossy broadcast power system.

      The next thing is to stand your beanstalk up you need to do something like ship it to geostationary orbit with a rocket and unwrap it - so we are talking about sending a vast amount of mass up there by rocket. Obviously from this a beanstalk would only make sense in the context of it being a small piece of a larger plan that involves getting incredible amounts of mass into orbit. There's been space snakeoil companies around before (eg. the Australian spaceport company which consisted of two people - I'm assuming one to scam the money and one to answer the phone) and unbelievably optimistic beanstalk people asking for money may well exactly that, since with current designs it would have to be built of unobtainium and requires robots powered by a technology Tesla abandoned a century ago once previously unknown laws of physics became clear.

  • One way to find out (Score:3, Interesting)

    by spineboy ( 22918 ) on Friday May 26, 2006 @06:52PM (#15413514) Journal
    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.

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

  • Is that the only problem? (Score:5, Interesting)

    by irexe ( 567524 ) on Friday May 26, 2006 @06:56PM (#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?
    • 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,

    • Re:Is that the only problem? (Score:5, Informative)

      by Jerf ( 17166 ) on Friday May 26, 2006 @09:27PM (#15414092) Journal
      The space elevator falls into the "Really Big" category of things, and using your traditional, every-day intuition about how things behave is actively unhelpful.

      We are talking a device ~60,000 miles long, feet wide, and paper-thin. So...

      I am thinking of storm type winds blowing it off balance

      The atmosphere extends up a few tens of miles at most. The Space Elevator is 60,000 miles long.

      making it resonate

      Compute the resonance frequency of a device 60,000 miles long.

      Even to the extent it's a problem, it's not like it's hard to react to; you've got all day.

      the danger to aeroplanes,

      What danger to airplanes? Are you envisioning something that's going to randomly and rapidly maraud across the surface of the Earth or something?

      It's way, way, way easier to dodge a stationary space elevator than all the other constantly moving planes in the sky.

      the disastrous consequences of breakage

      You're just assuming. Somebody beat me to pointing out this is false, but I want to point out you're assuming based on your everyday experience. It works poorly in this domain.

      For instance, what you probably think happens if there is a cut near the ground is the exact opposite of what happens, because your intuition is not set up for these kinds of problems.

      You need to turn to the math on this. Other people have worked out the issues. Most of what you consider the "real problems" aren't, and I don't mean that as a comment on your particular post, I mean it in general. Other things that you might never think about are, such as the concern raised in TFA, which I think are valid but aren't necessarily stoppers, and the ever-present question of whether we'll ever be able to turn out 60,000 miles of cable of any kind.

      Your intuition is worthless. Nothing personal; mine is too. Having studied the topics involved I can say I understand some of this stuff intellectually, but I can't say I understand it in my gut. But I do know not to trust my gut in this domain.

      (For what it's worth, similar concerns apply w.r.t. nanotechnology. Your intuition about how things work does not do very well at that scale. Our brains function at the in-between scale we all live and work in, and does not do well outside of that domain.)

      (60,000 mile note: I'm assuming the elevator design that extends in both directions from geosync, as I like the "throwing" ability it exhibits over the counter-weight-just-outside-of-geosync model. Other distances are possible but don't fundamentally change the results.)

      • Oh, bullshit (Score:3, Insightful)

        by Overzeetop ( 214511 )
        I will grant you that things of this scale do not fit the paradigm of everyday items (aka "everyone owns a washing machine"). But to dismiss some of these items is just asking for trouble.

        Compute the resonance frequency of a device 60,000 miles long.

        Which mode would you like to excite? Things don't always fail at the first resonant frequency. Many/most do, which makes the others that much more spectacular (and unexpected, I might add).

        What danger to airplanes? Are you envisioning something that's going to

  • Impossible (Score:4, Insightful)

    by eric.t.f.bat ( 102290 ) on Friday May 26, 2006 @06:56PM (#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.
  • "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 w
  • 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 payloa

  • Lunar Space Elevator (Score:3, Interesting)

    by randall_burns ( 108052 ) <randall_burns AT hotmail DOT com> on Friday May 26, 2006 @07:08PM (#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.
    • Because it costs a lot to go to the moon? Did you think through your question? At all?
  • 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 disc
  • 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).
    • Rotavators 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).

      Linking up with the end of a tether that is travelling in a circle at one to three kilometers a second sounds a lot like the sort of thing that the "Star Wars" missile defense program has been trying to do

  • 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 req

  • 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 predesti

  • Liftport already responded to this (Score:5, Informative)

    by Shrithe ( 972491 ) on Friday May 26, 2006 @07:19PM (#15413635) Journal
    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. (Score:3, Interesting)

    by thisissilly ( 676875 ) on Friday May 26, 2006 @07:21PM (#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.
  • 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
  • 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.

  • No imagination. (Score:5, Funny)

    by AnotherBlackHat ( 265897 ) on Friday May 26, 2006 @07:30PM (#15413686) Homepage

    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?

    • ObTrek [memory-alpha.org]:

      "Easy: Change the gravitational constant of the universe."

      "What?"

      "Change the gravitational constant of the universe, thereby altering the asteroid's orbit."

      "How do you do that?"

      "You just DO it, that's all. GAHH! Where is that doctor?"

      "What Geordi is saying is that we do not have the ability to change the gravitational constant of the universe."

      "Well, then...never mind."

      - Q, Geordi, Data

  • 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.
  • Is the space elevator an impossible dream? Well, duh! You are more likely to be able to beam up.
  • 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!
  • 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 f

  • Low-earth orbit -- monkey physics fails again. (Score:3, Insightful)

    by hypnagogue ( 700024 ) on Friday May 26, 2006 @08:52PM (#15413979)
    Payloads, or tourists, would simply ascend the cable into low-Earth orbit, eliminating the need for rocket launches.
    Well there's your problem right there -- you can't take a space elevator to low earth orbit. A space elevator that puts you in low earth orbit is moving at an angular velocity 18 times faster than the earth, and is therefore quickly destroyed.

    This isn't science, it's an ill-conceived editorial. Ignore this article and get back to work, my space monkey minions! Soon space will be ours!

  • It's a foolish person ... (Score:4, Insightful)

    by constantnormal ( 512494 ) on Friday May 26, 2006 @09:47PM (#15414147)
    ... that treats today's limitations as if they extend into the future indefinitely.

    So far as I can see, all the objections mean is that a space elevator cannot be built with the technologies we currently have -- and all of them seem to be of an engineering bent, as opposed to some fundamental theoretical problem. Engineering problems tend to get solved over the long haul.

    And even if the problems presented do turn out to be too difficult to construct an Earth-based space elevator, the technology could still be used on the Moon, which presents a much smaller challenge. I suspect that we already have the capabilities required to construct a lunar space elevator -- all that we lack is a permanent lunar base.

  • Somewhere over the rainbow ... (Score:3, Funny)

    by Infernal Device ( 865066 ) on Saturday May 27, 2006 @12:53AM (#15414664)
    Dammit! There goes my dream of hopping on the space elevator and punching the button for every floor ...

  • Cumulative damage problem solved long ago (Score:3, Insightful)

    by Beryllium Sphere(tm) ( 193358 ) on Saturday May 27, 2006 @01:13AM (#15414703) Journal
    Civil engineers simply build things stronger than they need to be. The safety margin allows a structure to absorb some damage from rust, rot, barges running into it and so on while remaining robust enough not to kill anyone.

    Set up an elevator, and when micrometeorite damage reduces the safety margin too much, use it to haul up its replacement.

  • Problems to overcome (Score:3, Insightful)

    by raider_red ( 156642 ) on Saturday May 27, 2006 @07:43AM (#15415441) Journal
    So, we've found a few flaws in our plan. I doubt that means that this will be scrapped forever. We're always developing new materials and new ways to apply them. Perhaps someone will come up with a nanotube which has a non-reactive sheathing that can resist oxygen erosion.

    There are also other avenues to space. We haven't heard much about laser powered propulsion, but there are possibilities as civilian and military researchers develop new and more powerful lasers. It would be a nice swords-into-plowshares project if we could use some of the military's new weapons for an application like this.

    Also, we don't necessarily need to be able to loft huge payloads at first. If we can send up small satellites or maybe even a small manned capsule repeatably and cheaply, it would be a good start. That is after all how we started with chemical rockets, so there's nothing wrong with starting small.

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