[extropy-chat] FWD [forteana] Re: lunar elevator

[Eugen Leitl]

On Sun, Jan 16, 2005 at 12:12:02PM -0800, Mike Lorrey wrote:
> 
> --- Eugen Leitl <eugen at leitl.org> wrote:

No, actually he didn't.

> > > get away from the geostationary altitude, the more force
> > > tangential to the orbital path is required to keep the system
> > > linear and stable.
> > > The orbital velocity has to be reduced approaching the planet//moon
> > > and increased in the opposite direction. You'd end up not with a
> > > perfectly straight cable, but a curved one, in the manner of the
> > > curving waterfalls in AC Clarke's Rendezvous with Rama.
> > > 
> > > Perhaps somebody with more maths than I have could explain if I've
> > > got the wrong end of the stick (or lift cable), but space elevators
> > > do sound like a bit of a non-starter to me.
> 
> An earth cable would curve because of lunar tidal influence only,
> putting tidal drag on the ends. A lunar cable at the inner lagrange
> point would be tidally locked with the moon, and would be curved by the
> tidal drag of the Earth. However, this only assumes that there is no
> other tension. If, for instance, the CG of the skyhook is slightly
> higher than geostationary orbit (or just earthside of the inner
> lagrange point), and the ground end is anchored sufficently, tension
> will keep the cable taught.
> 
> Because the system is in tension from these forces, anchoring the end
> to the ground will translate tangential forces into tension forces that
> are merely pre-existing frame dragging forces in the earth-moon system.

-- 
Eugen* Leitl <a href="http://leitl.org">leitl</a>
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