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Space elevators for laymen

  1. Nov 7, 2007 #1

    DaveC426913

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    I'm looking for good links to stuff on space elevators, particularly for laymen, or even school-age students.
     
  2. jcsd
  3. Nov 7, 2007 #2

    berkeman

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    What's a space elevator?
     
  4. Nov 7, 2007 #3

    DaveC426913

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    You jest.
     
    Last edited: Nov 7, 2007
  5. Nov 7, 2007 #4

    stewartcs

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  6. Nov 7, 2007 #5

    DaveC426913

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    Forgive me Berke. I could not bring myself to think you were asking seriously. :redface:
     
  7. Nov 8, 2007 #6

    berkeman

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    No worries. After seeing the wikipedia article, it is something that I'd heard of before, but when I saw you mention the term, I wasn't sure it was the same thing.

     
  8. Nov 8, 2007 #7

    DaveC426913

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    I rue the fact that the name beanstalk has not caught on. It is both very accurate and whimsical.
     
  9. Nov 8, 2007 #8
    There is a nice fictional book about the construction of a space elevator "Fountains of Paradise" by Arthur C Clarke. It's just fiction, Clark basically rejuvenated the concept of a space elevator that was first brought up by a Russian scientist, forgot his name.

    Today there is alot of proposals and designs of various space elevators. The only problem is the material required. It has to be super light and super strong, and not be corrosive. I think we already have that in form of carbon nano-tubes. But we lack the industry, and know-how to efficiently manufacture hundreds of miles of cable.

    There is dozens of clips on Youtube:

     
    Last edited by a moderator: Sep 25, 2014
  10. Nov 8, 2007 #9

    FredGarvin

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    Dave,
    You do realize that the mere posting of a question will bring every space elevator whack-o on the net in here in no time.
     
  11. Nov 8, 2007 #10

    Ivan Seeking

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    :rofl: I never realized that this qualifies as subculture, but it probably does!

    Are you implicity suggesting that the idea itself is cranky, or just that that it has a crank following?
     
  12. Nov 8, 2007 #11

    FredGarvin

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    I am implying that the following has a serious crank factor to it. Personally I think that the space elevator will never happen, even if we have thousands of plants turning out carbon nanotubes by the truckloads. However, like most things I am adamant about, I wait to be proven wrong.
     
  13. Nov 8, 2007 #12

    DaveC426913

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    I knew it had a big following, I'd no idea it was considered by some to be cranky.
     
  14. Nov 9, 2007 #13

    FredGarvin

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    I call it cranky because of all of the people that have come on this board, it seems that 95% of them think that once we get carbon nanotube production going that it will be a simple matter of hooking them together with a tether and some motors.
     
  15. Nov 9, 2007 #14

    Ivan Seeking

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    I tend generally to take the opposite view of things: I expect that it will happen until someone convinces me that it's not possible; and then I may or may not listen. :biggrin: But in this case, I recognize that the engineering challenges are daunting - the harmonics and wind shear forces being the ones the most come to mind for me.
     
  16. Nov 9, 2007 #15

    FredGarvin

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    The structural problems are the ones that I think of as being the biggest hurdles as well.
     
  17. Nov 9, 2007 #16

    russ_watters

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    Is that two questions or one...?
     
  18. Nov 9, 2007 #17

    russ_watters

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    As of today, engineering challenges are a distant second to the challenge of producing carbon nanotubes in such quantities. It's like discussing a bridge from New York to London - sure, there are engineering challenges, but the scale is what makes the very idea of building a bridge from New York to London asinine.
     
  19. Nov 9, 2007 #18

    Ivan Seeking

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    That doesn't seem like a fair analogy to me. I see it as being more akin to the transatlantic cable.

    In what way does the scale of this concern you? We know that this is the issue but that can change quickly. It doesn't justify declarations of failure. Besides, Fred was assuming that we have production of nanotubes going.
     
    Last edited: Nov 9, 2007
  20. Nov 9, 2007 #19
    In most industrialized countries, I think this would be close to impossible. Nobody would ever insure the construction and the environmental impact hearings would still be going on when the sun went dead.
     
  21. Nov 9, 2007 #20

    Ivan Seeking

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    How is this any worse than the space program; say a mission to Mars?
     
  22. Nov 10, 2007 #21
    A closer analogue might be building a nuclear power plant (OK, forget France - they make up for not liking Australian wine by being sensible about nuclear). My presumption is that a space elevator would involve a consortium of private industries and one or more governments. Imagine, if you will, a risk cascade analysis for a 50 km cable parting. What would a FMECA look like for hitting, say, Cleveland with that thing (sorry, Cleveland, but since you're trashing the Steelers this week, what goes around comes around)?

    Now, if you could get a government to run, and fund, the whole thing, then you probably could get it off the ground in much the same way the space program works. After all, you could probably put the elevator in some out of the way place (maybe the Canadian provinces or the Sonora desert) and the effects of mishaps could be mitigated.
     
  23. Nov 10, 2007 #22

    russ_watters

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    You are equating things that are several orders of magnitude different in scale. Ie, this is a much bigger project than a translantic cable - you are off by perhaps 3 order of magnitude. And there has never been a time since wires were invented (much less decades after they were invented) that they could only be produced in microscopic quantities and for thousands of dollars a gram. So production of carbon nanotubes will have to improve by, oh, I dunno, ten orders of magnitude in both cost and scale.

    So I would say, as a rough guess, that a carbon nanotube space elevator would be around 10^23 times more difficult to do than a translantic cable. It puts it on similar footing with things like anti-matter propulsion.

    In order to start with the assumption that 'anything is possible', like you said you do, you are assuming that we will discover new technology with the absence of any scientific basis for the assumption. Such assumptions are unscientific and wrong.
    Fred said "even if". I'm not completely certain what he meant, but my position, if I were willing to let the first "impossible" go, would be "even if" we get past the first 'impossible', there is another one right behind it. But I'm not willing to let the first ''impossible' go.

    BTW, I'm pretty sure you once suggested that it is best to start out with no assumptions. The 'anything is possible' assumption is the crank assumption that makes this a cranky subject.
     
  24. Nov 10, 2007 #23

    DaveC426913

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    That's silly. Antimatter propulsion is science fiction. We have NO form of antimatter propulsion. We do, on the other hand have the materials for a space elevator, even if the logistics and engineering challenges are fabulously difficult.
     
  25. Nov 11, 2007 #24

    russ_watters

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    Correct. And far-out science fiction too. The Enterprise's "impulse engines" are fusion reactors. That, at least, is something that isn't just technobabble-gibberish. Antimatter? It is barely even concievable right now.
    Not correct. The "challenges" posed by the materials far exceed any scientific/engineering endeavour ever undertaken by mankind. And that comes before the logistics and engineering challenges of building it. We can synthesize anti-matter and we can synthesize carbon nanotubes. And both on about the same scale.

    What would you say about the feasiblilty of buidling a DNA strand to the Moon? The very words put together into a sentence are pretty much nonsensical, right? Right now, (and for the past few decades) that's where carbon nanotube production is.

    It is silly.
     
    Last edited: Nov 11, 2007
  26. Nov 11, 2007 #25

    russ_watters

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    Lets do a little cost/scale exercise. No one has done it yet, but lets assume that it would be possible sometime in the relatively near future for a manufacturing plant to produce 1 meter of carbon nanotubes per year using a gigawatthour of energy. And lets assume that a million strands would be strong enough to support a space elevator. The cable would stretch to 1.5 times geostationary orbit (60,000 km). (power costs about $.1/kwh)

    How many plants and how long would it take to build and how much would it cost?
     
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