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Notes From 3rd Annual Space Elevator Conference
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."
This page seems to have some good links. Just check out the bottom of the page as it indicates if you're new to the idea of space elevators.
Wikipedia have a very good article on space elevators
Well, actually, a little further out than GEO, so that the center of mass is at GEO.
As for wind -- well, you situate it where the wind is minimal. Remember, since it's synched, it's not generating "wind" by slicing through the air. All you'd have to worry about is the wind that is actually blowing past the (stationary) Earth.
The Mongrel Dogs Who Teach
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.
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.
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.
Nothing.
It's a ribbon. It's literally nearly equal to the weight of an equal width of Saran Wrap.
How much unrolled saran wrap do you have to drop on someone before it hurts them?
How many buildings will be devastated by having something that flimsy dropped on them?
The devastating space elevator fall is bad science fiction. If it breaks, stuff above will stay in orbit, and stuff below the break will fall harmlessly.