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

[Mike Lorrey]

--- Eugen Leitl <eugen at leitl.org> wrote:
> > 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.

=====
Mike Lorrey
Vice-Chair, 2nd District, Libertarian Party of NH
"Necessity is the plea for every infringement of human freedom.
It is the argument of tyrants; it is the creed of slaves."
                                      -William Pitt (1759-1806) 
Blog: http://www.xanga.com/home.aspx?user=Sadomikeyism


		
__________________________________ 
Do you Yahoo!? 
Yahoo! Mail - now with 250MB free storage. Learn more.
http://info.mail.yahoo.com/mail_250