Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: stuartr on 27/10/2008 18:03:52

Title: How much tension would there be on a space elevator cable?
Post by: stuartr on 27/10/2008 18:03:52

On a recent TV show scientists were demonstrating how a space elavator might function The evavator unit  'climbed' a wire suspended from the roof of the building.If a full scale elevator was constructed from a geostationary space station down to earth how much tension would be on the cable.What shape would the cable take down to earth? Straight down or in an arc?

_{Mod edit - Formatted the subject as a question - please do this to help keep the forum tidy and easy to navigate - thanks!}

Title: Re: How much tension would there be on a space elevator cable?
Post by: lyner on 27/10/2008 18:36:18

The stress wouldn't be the same all the way along the tether. It could involve a vanishingly small force applied to the satellite if the wire had no mass. The weight of the bits near the ground would mean that the force would be a compression and very little tension at the other end.
 If you make the tether longer than the geostationary length, then the  ship would 'lag' behind and be pulled round by the Earth. This would introduce more tension and reduce the compression at the Earth end. This arrangement would be more stable and keep the tether taught.
Whatever the material used, the tether would have considerable mass (and would need to be v. strong).
Because the g field would be stronger near the Earth, I should expect a curve in the tether (because of its mass). I reckon it would 'sag' towards Earth at the lower end because the ship would be 'behind' the base location. A sort of modified catenery.

I really fancy this as the best way to establish a seriously big presence out in space. A huge investment but easy to get all your stuff up there for all future projects.

Title: How much tension would there be on a space elevator cable?
Post by: LeeE on 30/10/2008 15:36:52

Just for reference and a reasonable read too:

http://en.wikipedia.org/wiki/The_fountains_of_paradise (http://en.wikipedia.org/wiki/The_fountains_of_paradise)