posted
New Scientist sites always take ages to load, KoM; I'll bet your browser is just timing out, as the link still works for me. Try just going to www.newscientistspace.com and see if you're able to see their front page. If so there should be a link for the story in question.
Posts: 16059 | Registered: Aug 2000
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posted
Hmm, I read an article about this type of idea earlier, and I thought we didn't have the materials yet invented that would enable this cable to be both strong enough and cheap enough to be effective. I'll have to do some searches...
Posts: 1256 | Registered: May 2005
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Anyone read "The Fountains of Paradise" by Arthur C Clarke?
My question is: How are they going to lift 62,000 miles of carbon into orbit? Clarke had them manufacturing "diamond fiber" using carbon-rich asteroids brought into orbit for that purpose, but we're no where near ready to do that.
Posts: 3735 | Registered: Mar 2002
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quote:How are they going to lift 62,000 miles of carbon into orbit?
That's not the biggest problem. The biggest problem is that the cable has to be (at a minimum) strong enough to support its own weight. If you were to take a cable and begin lifting it by a balloon, eventually the weight of the cable would exceed the tensile strength of the cable and the cable would break. The length at which this will happen is independent of the diameter of the cable since both the strength and the weight are directly proportional to the diameter. This analysis only changes by a tiny bit when you fix both ends of the cable and not just one.
The calculation is pretty simple if you assume constant gravitational excelleration and for graphit fiber gives you a maximum length of the cable of around 40,000 km or 26,000 miles. Of course the assumption of constant gravity is really bad over that distance so the equation would have to be integrated but I somehow doubt that this would make the factor of 3 difference needed for the cable to simply hold its own weight. Add onto that the weight of the stuff you are trying to move up and down the cable plus shear stress due to wind and any assyncronicity between the top and bottom of the cable and it seems clear that we are going to need some serious improvements in materials technology to get the idea to work.
Posts: 12591 | Registered: Jan 2000
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posted
Well, really, a factor three? A mere half an order of magnitude? Doesn't sound impossible at all; that's well within the realm of just chucking money at it. Also, note that you can make the cable thicker at the top, where it's carrying the most weight.
Posts: 10645 | Registered: Jul 2004
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quote:Originally posted by Lalo: Title of thread stolen from a /. comment, I take it?
Actually, no; that isn't something I'd do without attributing it. I was fairly pleased with the title though. How close is it to the /. comment?
Posts: 16059 | Registered: Aug 2000
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I don't even get how that's supposed to work. How do the robots lift a 100 tons of anything up a cable less than an inch thick?
I guess I sort of understand how they're going to build it, and the new materials being invented with nanotechnology seem like they could get the job done, but I understand the idea behind how this whole thing works.
Posts: 21898 | Registered: Nov 2004
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posted
Acually if this was done for real the plan is not to bring the tether up but to drop it from space and extened another one in the opposite direction to even out the weight pull (am i right about that) so your arguements don't matter.
Secondly its more not that the cable lifts but that the robots climb up the ribbon into space.
Yet i never heard of these people trying and never knew about these test. very interesting.
Posts: 250 | Registered: Jun 2005
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posted
Sorry, that sounded WAY more accusatory than I meant it to.
Here's the /. comment:
quote: 1 down, 61,999 to go! (Score:4, Insightful) by lannocc (568669) Alter Relationship <lannocc@lannocc.com> on Wednesday February 15, @03:16PM (#14726710) (http://www.shawn-wilson.com/) A little progress is better than no progress. --
posted
You have to admit that it's a fairly obvious thing to say. (No offense, Noemon. I'm not saying that you're unoriginal, but rather that it's not surprising that someone in the world wrote something similar.)
And anyway, I like Noemon's better. Posts: 9945 | Registered: Sep 2002
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posted
I'm glad to hear that Lalo; it stung a bit, and I couldn't think of anything I'd done or any interactions we'd had that would have prompted you to take that kind of tone.
Thanks Jon Boy!
My motivation for phrasing it that way was actually that I've noticed that a lot of the science links I post are to things that are so far from actually being proven theories or developed technologies. I wanted to make it clear that while this was interesting, it was a project in its infancy.
Posts: 16059 | Registered: Aug 2000
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quote:Acually if this was done for real the plan is not to bring the tether up but to drop it from space and extened another one in the opposite direction to even out the weight pull (am i right about that) so your arguements don't matter.
Secondly its more not that the cable lifts but that the robots climb up the ribbon into space.
It doesn't matter whether the cable is lifted or dropped. In the end the tension in the cable must be greater enought to support the weight of the cable. It doesn't matter whether the cable lifts the loads or robors climb up the ribbon, the cable still has to support the weight of the robots, load and force required to lift them. It's pretty simple physics.
A tapered cable is a possible solution to the problem, I'd like to see the actual feasability study for this. I think it would be interesting. Right off it seems like the problems with maintaining a cable that is longer than the circumference of the earth would make this idea impractical from the get go.
Posts: 12591 | Registered: Jan 2000
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I'm glad to hear that Lalo; it stung a bit, and I couldn't think of anything I'd done or any interactions we'd had that would have prompted you to take that kind of tone.
