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Space Science Technology

Notes From 3rd Annual Space Elevator Conference 469

colonist writes "The Space Elevator: 3rd Annual International Conference was held recently. Blaise Gassend, a PhD student at MIT, took notes. The main obstacle is still the material: transferring the strength of the nanotube to the ribbon. Other topics include: the nanotube tether Centennial Challenge; Elevator 2010, a challenge for a 250 kg climber to climb a 16 km tether; objections and refinements to Bradley Edwards' design; non-equatorial space elevators; replacing the term 'space elevator' with 'space bridge'; testing the space elevator material on cable cars; science; defense and economics."
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Notes From 3rd Annual Space Elevator Conference

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  • Incredible idea (Score:2, Interesting)

    by mboverload ( 657893 )
    This is such a crazy idea, but so awesome. Come on, a huge ribbon made of nanotubes being pulled by the earth and a huge weight in space, this is just plain awesome. Imagine a huge mofo ribbon going straight up as far as you can see and imagine. This will be a great site and thankfully (and hopefuly if Bush don't draft me first) I will live to see it.

    This will change everything. Transporting to space will be (relitive to rockets) DIRT CHEAP. Props to them for their vision and their crazy idea that jus

    • ...Imagine a huge mofo ribbon going straight up as far as you can see and imagine...
      And that, my friend, is a real phallic symbol :-)
  • How on earth are they going to cope with the wind forces, the jetstream, gravity, the earths spin, earpopping, in transit entertainment, lightning, costs, kids, aliens, terrorism and the fact that their's nothing in space to go up to yet.

    P.S.
    EMACS already does this.
    • That's because it's so expensive to get stuff up there. A space elevator would solve that (albeit at great initial expense no doubt ;)
    • by Anonymous Coward on Tuesday July 06, 2004 @06:28AM (#9619778)
      Christ, why does everything we ever dream of nowadays have to consider terrorism as an influencing factor? What is this obsession with living in fear all the time? Have we been so indoctrinated that we now automatically think in these terms? I say screw the "terrorists" whoever they may be. Perhaps if we spent more time dreaming and less time trying to fight fear with fists we'd be a lot better off anyways...
      • Especially if yuo consider the fact that Civilisation doesn't have Terrorism built in :-)

        Maybe I should develop a plugin and sell it. Peeps like grandparent poster prolly couldn't resist buying it to increase reality in gameplay
      • by ctr2sprt ( 574731 ) on Tuesday July 06, 2004 @07:44AM (#9620042)
        Oh, come on. Your first thought upon hearing of the space elevator wasn't "what happens if it breaks?" Who cares if science suggests it won't be a catastrophe? Most terrorists do not exactly subscribe to the latest scientific journals. A lightbulb will go off in one of their dim minds and they'll try to ram a plane into the cable, or the tower, or whatever, hoping it will somehow dislodge the asteroid from orbit and send it crashing into Washington D.C. or something. It'd make a great scifi action movie, wouldn't it?

        And don't forget it'd be a tremendous icon of Western achievement. You'd better believe everyone in the US, or whatever country eventually builds one, would be proud as hell of it. The media would be going on and on about how it'll usher in a new age for mankind, and so on, and so forth. If terrorists could somehow take it out, wouldn't that have tremendous psychological value? Remember that they chose the World Trade Center and Pentagon to strike at us, two (or three) buildings that symbolized, to them, everything that's wrong with the US. Wouldn't a tower that reaches into the heavens (hello, Tower of Babel?) symbolize that even more?

        It's quite reasonable to take terrorism into consideration when designing a structure. As long as you don't let it make the decision for you. Saying "We'll increase the no-fly zone from five miles to twenty five to give us time to shoot down hijacked planes" is good planning. Saying "We just can't eliminate the possibility of terrorism, let's just not build a space elevator" is not.

        • by TulioSerpio ( 125657 ) on Tuesday July 06, 2004 @10:35AM (#9621323) Homepage Journal
          Offtopic:

          Remember The Oklahoma Bomb [wikipedia.org]?
          Who are "us"?
          Who are "them"?
        • by Anonymous Coward on Tuesday July 06, 2004 @10:37AM (#9621358)
          Actually, it wasn't. My first thought was, "cool", but hey...

          What really irritates me is that this fear of terrorism is so unreasonable. It's almost akin to the "Won't someone think of the children scenario". The US has been the target of relatively few domestic attacks and of those, one was carried out by a US citizen. Despite this, the fear of terrorism has pervaded the national consciousness so fundamentally that any discussion is now subject to these apocalyptic "what if?" scenarios.

          Yes it would be a very bad thing (tm) if someone crashed an airliner into a space elevator, but when that progresses from being a notable, if incredibly unlikely concern, to a point where such fear of the irrational drives society itself, then who cares what the "terrorists" do, they've already won. Of course we should build with the lunatic with a cause in mind, but build we must. This realisation is slowly being eroded. There is a phoenix risen from the ashes of 9/11 filled with hatred and fear, and it is a frightening beast indeed.

          Europe has had to live with this for far longer than the US, yet they live in a far freer, far more secure environment than we could ever hope to have. I re-iterate, screw the terrorists. It's the only way we all win.
        • somehow dislodge the asteroid from orbit

          Why did the scifi writers think that an asteroid would be used as the counterweight? There's no reason for that. Carbon is cheap - moving an asteroid is not. Just make the cable twice as long, and use the rocket remains as the counterweight. Easy enough. Can we propagate this idea? Here it is again: no asteroid counterweight!

          It's quite reasonable to take terrorism into consideration when designing a structure.

          Thankfully, the design of the structure takes it
      • For the same reason that all software has to be secure these days.
    • There has been lots of /. articles on the Elevator for years. You missed them all???

      And then you get modded up by others who doesn't keep up?! :-)

      Please RTFA/RTFM etc.

    • fact that their's nothing in space to go up to yet.

      Correct me if I'm wrong (and I'm not), but this is primary reason to build the space elevator: to put something up there to begin with. Sure we can add on to the space station but imagine the number of projects that'll open up when their funding support needs suddenly drops by 50% and more.

      earpopping? transit entertainment? You're putting people on it? It's a cargo elevator in concept although I suppose you could put people in it if they were proper
    • ...and the fact that their's nothing in space to go up to yet.

      Nothing except the rest of the universe. Or are they adding that in later?

    • Simple (Score:4, Insightful)

      by HarveyBirdman ( 627248 ) on Tuesday July 06, 2004 @09:44AM (#9620745) Journal
      You just announce that if the space bridge de-orbits due to terrorist activity, then Mecca orbits due to anti-terrorist activity.

      Harsh? Yeah.

  • by Timesprout ( 579035 ) on Tuesday July 06, 2004 @06:24AM (#9619764)
    The space elevator is a great idea but no human has the mental strength to listen to elevator musak for the length of time the trip will require and still retain their sanity.
    • not to mention the pure embarassement of trying to hold a fart in for the entire 4 day journey

      I dont think i'm man enough for that task.......
    • no human has the mental strength to listen to elevator musak for the length of time the trip will require and still retain their sanity.

      THIS is why I bought a forty-gig MP3 player!

  • by feilkin ( 790260 ) on Tuesday July 06, 2004 @06:24AM (#9619765)
    I think that it should be taken into consideration that almost every major project of construction was deemed impossible. Very good examples of these are the famous Golden Gate Bridge and the EuroTunnel. Everyone said it was impossible, yet they were completed. As technologoy in this area continues to develop, I think that this may be able to become a real and practical idea sometime down the road. It may not be possible now, but in ten years, who knows?
  • by colonist ( 781404 ) on Tuesday July 06, 2004 @06:32AM (#9619794) Journal
    Blaise Gassend's page mentions Andrew Price's list of alternative names:

    space bridge
    space way
    space rail

    'Space bridge' got the most approval from the audience.
  • by TheTXLibra ( 781128 ) on Tuesday July 06, 2004 @06:36AM (#9619806) Homepage Journal
    Forgive my ignorance, MEMS and Nanotech has fascinated me for a while, but I don't know enough of the math behind them to tell if this is true. My grandfather, rest his soul, once told me of something called the Sailor's Rope Rule, which effectively says that the weight a rope can support is diminished by its length. Thus, a 500 lb. rope might support 500 lbs when there's less than a foot or so in length between the pully and the weight, but might only support 250 lbs when there is a good 100 ft. or so... The actual support degradation of course depends upon the width of the rope and the material the rope is made of.

    So what I'm wondering is, does the same apply to the weight supported by nanotubes and other molecular chains. I figure it has to be less of a degradation due to the ionic bonds involved, but it would seem to me that, unless some Quantum rule is involved dealing with extremely small-scale weight supporting chains, that they might never overcome this problem due to the sheer thinness of the tubes, chains, etc. It might be extremely strong material, but if it's width is only a few atoms wide, wouldn't this material be, at least in single lengths, more or less useless by the time it got to a respectable length? This is, of course, excluding bundles, which make the most sense, I'm really just curious if the same rule applies to nanotubes as applies to rope.

    • You're not taking into account nanobot maintainence.
    • by gilroy ( 155262 ) on Tuesday July 06, 2004 @06:52AM (#9619861) Homepage Journal
      The rule probably refers to the fact that the rope has to support its own weight in addition to the mass you're hanging. The longer the rope, the more of its own weight has to be supported.

      But don't worry -- the engineers looking into the starbridge know about this effect and include it. That's how they get estimates of the required tensile strength.
    • by JosKarith ( 757063 ) on Tuesday July 06, 2004 @06:56AM (#9619881)
      The degradation rule is based on small defects in the rope - your rope may be able to hold 500lbs but every 10' has small flaws that weaken that by 25 lbs...
      It's the same principle as the chain rule - in that it's only as strong as the weakest link. Think of the rope as a bundle of miniscule chains and you're halfway there.
      In theory a nanotube shouldn't have these defects. In practice...yeah right. I figure there will have to be a fairly major degree of over-engineering with regards to stress tolerances in this.
      Projects like this are possible - hell even feasable, but humanity needs to pull it's finger out of it's ass to get these up and running. It's really simple - barring a sudden discovery of practical anti-gravity or some other esoteric technology we have until the fossil fuels run out to work out a way of getting bulk loads out of the gravity well. Otherwise, we're gonna be stuck here wallowing in our own filth forever.
      We have passed the peak of oil production - easy to get supplies are starting to run low, and the rest of the oil is bound in things like "dirty shale" and are increasingly difficult to access. Time is running short, and posing and posturing do nobody any good.
      • by vidarh ( 309115 ) <vidar@hokstad.com> on Tuesday July 06, 2004 @07:08AM (#9619922) Homepage Journal
        I call bullshit. Either a 10' segment can carry 500lbs or it can't. If it can, then no amount of "small flaws" will affect it by definition. Combining these 10' segments together don't affect the lifting capability of any 10' segment, nor does it affect the combined weight of the rope and any attached object that can be hung from the top of the rope.

        Your example of a chain is flawed and doesn't match what you suggested for the rope - A chains strength doesn't weaken for each extra link because of "small flaws", it stays the strength of the weakest link regardless of number of links.

        But the moment you start hanging it down you need to take into account the weight of the chain itself, and the chain, just as a rope, will be able to lift less additional weight the longer it is because the strain on any point of the chain/rope is equal to the weight attached PLUS the weight of all of the chain/rope below it.

        • by JosKarith ( 757063 ) on Tuesday July 06, 2004 @07:48AM (#9620056)
          Because a rope is not a totally solid system the fibres can and will slip against each other . If a fibre has a 1% chance of having a flaw in a 1' length, it stands to reason that a 100' length has a good chance of having a flaw somewhere along it's length - 73% to be precise. If your rope has 100 strands then 73 of those strands have a flaw. The more flaws you have, the more chance of several flaws close enough together to seriously compromise the strength of the rope.
          It's all about probabilities and statistical averages. And yes, that weight of the rope increases as the length increases, but the weight of the rope is usually trivial compared to the usable loading.
      • by Cecil ( 37810 )
        We have passed the peak of oil production

        Speaking as someone who works in the oil and gas industry, I can say without hesitation that this is untrue. Peak oil has been looming for the last 10 years at least, yet it keeps being pushed ahead by improvements in recovery technology. This trend does not show any sign of slowing, at the moment. Remember, an average oil reservoir still has 85% of its original oil still there. Recovery factors these days have grown from 10-15% to 20-25% and rising. Yes, it is mor
    • by vidarh ( 309115 ) <vidar@hokstad.com> on Tuesday July 06, 2004 @06:59AM (#9619887) Homepage Journal
      What this is essentially saying is that the rope needs to be able to support it's own weight in addition to the weight attached to it, which means that the longer the "rope" you need the lighter it needs to be compared to it's strength for you to be able to lift any reasonable amount of mass, or for it not to be torn apart by it's own mass.

      That's why you need a really strong material for a space elevator - if it wasn't for the weight of the "rope" itself you'd only have needed a material strong enough to handle the weight of whatever you wanted to transport up it, but that is a miniscule amount of the total strain on the elevator.

    • by Fzz ( 153115 ) on Tuesday July 06, 2004 @07:05AM (#9619910)
      Thus, a 500 lb. rope might support 500 lbs when there's less than a foot or so in length between the pully and the weight, but might only support 250 lbs when there is a good 100 ft. or so...

      Ignoring the weight of the rope itself, probably the main reason for this rule-of-thumb is the difference between dynamic loading and static loading.

      If you (accidentally) get something bouncing on a short rope, the bounce will damp out pretty quicky and the period of oscillation is short. If you get something bouncing on a long rope, it will bounce for a while, and the rope is stretched for much longer with each bounce. It doesn't take all that much of a bounce to double the load on a rope, and perhaps take it past its elastic limit.

      I'm guessing, but I think that pre-synthetic ropes probably can be briefly overstretched without losing strength because they knit back together again. If you continuously overstretch them, the fibres probably don't get a chance to recover before the slide past each other a little more, and so on.

      So my guess is this doesn't apply nearly so much to modern synthetic ropes. In the case of a space elevator, I'd hope they'd try really hard to avoid excess dynamic loading.

  • by falsemover ( 190073 ) on Tuesday July 06, 2004 @06:52AM (#9619867)
    According to new Nasa research http://www.nasa.gov/news/highlights/index.html they can fully fund a new US$2 billion research project by selling the franchise to the revolving restaurant at the top and logo placement along the length of the ribbon itself. Already, they have received competitive bids from Chez Panisse, McDonalds, and Bert Farnsdale's New York hotdog stand. This is the start of the holy mothership of bidding wars.
  • by colonist ( 781404 ) on Tuesday July 06, 2004 @07:01AM (#9619900) Journal

    The Spaceward Foundation [spaceward.org] is creating the Elevator:2010 program:

    Our first program, Elevator:2010, is a public challenge centered around the Space Elevator concept, offering a substantial prize for the first laser-powered tether climbing demonstration that can meet a specific criteria.
    The challenge is intended to be difficult (hence the 2010 deadline) and physically impressive - using a several miles high balloon-suspended tether, and a beamed-power system larger than has been built to date.
    Around this challenge, we intend to create a comprehensive program with significant presence at technology and science museums, as well as public events (such as fairs and air shows), featuring smaller-scale displays and competitions, and allowing for individual hands-on participation at all levels, from high-school teams to private enthusiasts.
  • by Dissectional ( 528344 ) on Tuesday July 06, 2004 @07:30AM (#9619987)
    I recall Arthur Clarke pitching the initial concept for a Space Elevator some time back, and revisited the idea in 3001 : The Final Odyssey - in which he depicted planet Earth having a fully functional ( four actually ) space elevator system; which facilitated a subset of human civilisation living in low earth orbits in reduced gravity - thus invoking presumed benefits of doing so.

    Anywho. He spoke a couple years ago, subsequent to 3001's release on how at the time of writing, such a feat was nigh on impossible at this stage - as the materials to construct the 'elevator' were yet to be developed. Until now. The carbon molecule Buckminsterfullerene ( C60 ), also known as 'Fullerene', is supposedly strong enough to actually make such a concept a reality - which is in part the reason the space elevator was hurled back into the limelight of late.

    I think its a fascinating idea - which until we develop propulsion systems beyond the primative scope of the 1,000+ year old firecracker concept, certainly seems a more elegant way for the species to venture into Space more regulary. Or, at the very least, be the catalyst for what could perhaps become the initial stepping stones to establishing a permanent presence in space which will hopefully later lead to space initiated launches.
  • What happened to the intermediate designs that don't provide all the benefit but also don't require two decimal orders of magnitude performance improvements? I didn't see anything in the

    Brin's electromagnetically boosted tether design (Tank Farm Dynamo, 1983) would reduce the amount of delta-vee needed for orbit, at least allowing for cheaper shuttles. It's not much of a benefit, but we could build it today.

    A rotating tether that dipped into the atmosphere would allow much greater safety margins and have a much less dangerous failure mode. You could practically rendezvous with one from an X-prize vehicle, and you wouldn't need to build a climber... just grab the tether, hold on for one rotation, and let go.

    The big problem of course is that extra delta-vee isn't free, and the tether would lose altitude every time it's used (this is a problem for all tether designs, really). So, the throughput rate would be limited by the time needed to re-boost the tether between launches: using a high-efficiency low-thrust drive would be cheapest but require the longest "recharge" time.

    Longer term, it would get a boost from de-orbiting mass from space: if you return a ship of the same mass to Earth at the same time as you boost one to orbit the net delta-vee is zero. If you have more ships going up than coming down, bring a nickel-iron asteroid into orbit and just feed a chunk of metal that weighs the same as the ship in from a higher orbit, it'd get de-orbited and released at 100km. Make it in an airfoil shape (a crude glider) and you can recover it... just deliver it to an asteroid-iron junkyard out in the middle of New Mexico or something.

    THAT would make Rutan's barnstormer spacecraft a stage in developing a new industry, instead of a stunt.
  • by Will_Malverson ( 105796 ) on Tuesday July 06, 2004 @07:39AM (#9620018) Journal
    We can't change its name to be a 'space bridge'. If we did, we couldn't have the same hilarious jokes in every Slashdot article about elevator music.

    Won't somebody please think of the hilarious Slashdot jokes?
  • And what if the tether breaks and drops on Earth: a wire so small you can almost not see it, but stronger than any other material. It will acts as a knife and cut through almost everything. A sweeping tether could make a whole area unhabitual. Very dangerous stuff.
    • Re:Killed by tether (Score:4, Informative)

      by argent ( 18001 ) <peter@@@slashdot...2006...taronga...com> on Tuesday July 06, 2004 @08:20AM (#9620177) Homepage Journal
      I wouldn't worry about being killed by a carbon fiber making meteoric reentry. It wouldn't be like the disaster in the Mars trilogy, or even like shadow square wire... by the time it hits it'll be more like laser toner, the stuff is strong in tension but it burns quite nicely: Nanotube Explosions [iu.edu]
    • by oni ( 41625 ) on Tuesday July 06, 2004 @11:38AM (#9622074) Homepage
      And what if the tether breaks and drops on Earth

      1. Everything above the cut would stay in orbit. Everything below the cut would fall to Earth. The base will be on the West side of the Atlantic Ocean and will therefore have hundreds of miles of water to its East. Most of the dangerous things that can cut it are in LEO, which is less than "hundreds of miles" away. So more than likely everything that falls to Earth will fall into the Ocean.

      2. Just because the cable has high tensile strength that doesn't mean it is indestructible. You can bind a person's hands with speaker wire and no matter how strong the person is, they wont be able to break free. But that doesn't mean the wire is magically indestructible. It's just wire.

      3. In the current issue of Discover Magazine, the concept they write about calls for a cable a few feet across, but only as thick as a sheet of paper. I don't know why so many people assume we are talking about an elevator to lift humans. The first several incarnations will be for light cargo only. Anyway, a cable as thin as a sheet of paper will mostly burn up as it falls through the atmosphere. If any of it survives, it will be shattered into pieces (not together as a whole cable) and will have the same terminal velocity as a sheet of paper. It will just flutter to the ground without hurting anyone. If you are lucky enough to live in the debris path, you can collect the stuff up and sell it on ebay.

      So many people make the mistake of assuming that there is some horrible danger that only they will recognize. As if hundreds of scientists around the world are diligently studying this and then Frans Faase of slashdot comes along and says, "what about this problem here?" And all those scientists will just throw up their hands and say "oh god, we all have PhDs but we didn't think of that - we aren't as smart as Frans." Right.

  • by MetaMarty ( 38276 ) on Tuesday July 06, 2004 @07:57AM (#9620092)
    Something I never heared anybody about: Where does the kinetic energy come from that the cargo gains when ascending into orbit? Somehow the cargo needs to gain a huge amount of kinetic energy, because the top of the elevator moves several km/s faster then the bottom. If nothing compensates for this energy, the counter weight would gradually slow down and deorbit, so there must be some kind of propulsion in the counterweight, pushing it prograde whenever cargo ascends and pushing retrograde when cargo descends. Anybody got more info on this?
    • The energy is provided by the climber, which in the current designs is powered by a beam of light coming from a ground station.

      The angular momentum for the orbit comes from the rotation of the earth. If you would launch billions of tons of rock using a space elevator, the rotation of the earth would slow down noticeably.
  • Rotovator(tm) (Score:5, Interesting)

    by Baldrson ( 78598 ) on Tuesday July 06, 2004 @11:02AM (#9621658) Homepage Journal
    Hans Moravec's Rotovator(tm) picks up hypersonic (near mach 12) payloads from an altitude of 100km and slings them to orbit.

    Current proposals [tethers.com] for implementation of the Hans Moravec's original design [cmu.edu] rely on a hypersonic air-breather of advanced aerodynamic design like the Boeing DF-9 (that exists only on paper).

    Can /. readers think of anything likely come along in the near future that could take paylods to 100km and mach 12?

    Probably the same thing that is driving the bureaucrats to make all this noise about space elevators now [xprize.org].

    A key to the Rotovator(tm) is getting hub mass in place to keep it out of the atmosphere while it picks up mass from 100km@mach12 -- but that mass can be any old space junk -- at least at the hub where it counts the most for high strength materials like carbon nanotubes. However, you can do a Rotovator(tm) with off-the-shelf commercially available fibers and still have a factor of 2.

    Nice thing about Rotovators(tm) is that they can be built with much lower capitaliztion over a much shorter period of time using existing commercial materials. All you need is a bunch of mass orbiting near earth, some quite-doable tethers, and sufficient manuverability and speed in the atmospheric leg to hook up with the tether as it reaches the nadir.

    • Mod this up! (Score:3, Informative)

      by mrright ( 301778 )
      I wish I had modpoints. Rotovators are indeed much more practical than space elevators. They do not require exotic new materials such as carbon nanotubes. They can be built with cheap materials like spectra or zylon fiber. They are also much shorter (100km instead of 36000km) and more flexible.

      This system [tethers.com] could double the payload capacity of launchers to geosynchronous transfer orbit or pick up small payloads from suborbital trajectories.

      This could be built today. Rotovators are also a very good addition
  • intermediate goals (Score:3, Insightful)

    by bigpat ( 158134 ) on Tuesday July 06, 2004 @12:42PM (#9622792)
    "Elevator 2010, a challenge for a 250 kg climber to climb a 16 km tether"

    How about something possibly a bit more realistic, like a 250kg climber climbing a 50 meter tether.

    The problem that I have with the space elevator fanatics is that they are setting goals well in advance of the science and engineering which usually leads to disillusionment and could scare away investors in what is a promising area of development. Carbon nanotubules hold great promise, but it is still just promise until they can be manufactured in suffient lengths and with sufficient ease to be practical for any use let alone a space elevator.

    If carbon nanotubules are going to be useful, we will see them used as building materials for much smallers things first. Perhaps as robotic tendons, or longer bridge spans, weaved into lighter armor for vehicles... I could think of many important applications which could use shorter easier to make lengths of nanotubules and would provide the neccessary experience to determine if a space elevator might be practical.

    Sometimes small steps are big.
    • by jc42 ( 318812 )
      Indeed, we are a long way from making 40,000-km-long carbon nanotubes. One serious question is how practical it is to depend on something like this being built.

      But it's only been a few years since the first carbon nanotubes were created. The first were only nanometers long. Then others reported making some that were micrometers long. And a couple of months ago, there was the first report of millimeter-long nanotubes [azonano.com].

      This is rather rapid progress, around 9 orders of magnitude in about a decade. And th

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