On Sat, 26 Jun 2004 23:15:26 GMT, "Bill Daniels"
wrote:


"Howard Eisenhauer" wrote in message
news
On Fri, 25 Jun 2004 22:42:15 -0700, Richard Riley
wrote:

On Fri, 25 Jun 2004 20:47:03 -0500, Big John
wrote:

:Scientist Sees Space Elevator in 15 Years
:
*Snip*


H.

This space elevator thing is elegant in a Newtonian sort of way but I
suspect that there is a lot more to it that hasn't been completely thought
out.

You may well be right- not really my field but I've heard the math is
the same as applies to suspension bridges, thats to say well
understood.

They say put it on the equator where the winds are low. Well, they are low
most of the time but there is always the occasional typhoon.

True, but anything with the kind of strength we're talking about here,
under that amount of tension ain't gonna be much bothered by the
occaisional blow.

Then there are the electrical effects. A carbon nanotube cable will conduct
electricity pretty well. Some claim it's a room temperature superconductor
candidate. A tropical lightning strike can be several million amps and this
cable will be a pretty good lightning rod. There's the induced voltages
too. The normal atmospheric potential gradient is several million volts per
meter.

Last I checked deltaV/m was more liket ~200V. I heard the speculation
about nanotubes being superconductors a few years ago back before they
were able to produce them in decent quantities but haven't heard
anything since, If they really are I think somebody would have noticed
by now. To bad though, a superconducting space elevator would be a
neat way to generate "free" power, a-la the NASA/Italian experiment
with a tether a few years back. .

What about tidal effects? Twice each day the Moons gravity will pull on the
structure.

Bill Daniels

Yes, it will. Geosync satellites get pulled around quite a bit by the
moon (& sun's) gravity. Then they get pulled back again., Not a
biggie.


H.