[extropy-chat] Re: Space Elevators

[Mike Lorrey]

--- Damien Broderick <thespike at satx.rr.com> wrote:

> At 11:30 AM 8/3/2005 -0500, Jay wrote:
> 
> >As I remember, the latest problem with a SE was vibration,
> harmonics,
> >and damping. Damien Broderick gave some attention to this during the
> >conferences. Any comments, D.B.?
> 
> I'm fairly clueless when it comes to the fine grain detail. All I
> recall is the suggestion by Clarke and others that the cable might
> be able to avoid satellites by harmonic twanging. I believe Spike
> had objections to this.
> 
> But the problem I have simply conceptualising this thing is that I
> still don't understand *how* the cable is lowered. My intuition tells
> me that if you simply extrude it toward the ground, it's going to
> rise slowly and majestically to the same height above ground as
> the station -- that is, back into geosynchronous orbit -- where
> it will hang in a nice curve up ahead of the station, while the
> ballast end will curve downward to hang behind it like a tail.
> Don't tell me gravity will keep the cable straight -- every part
> of the thing has the same GEO velocity it started with. Or am I
> missing something extremely obvious?

Yes, tidal lock will give the cable a 1 revolution per day spin, so
that its earth end will always travel at the velocity of the earth's
surface (a few hundred mph in absolute terms), and the end above GEO
will travel faster than GEO orbital velocity, such that the average
velocity over the entire length will be GEO velocity and that center of
mass will be at GEO, 22,300 miles.

Gravity at a small scale is weak. Over a large scale it exerts a rather
massive torque. It is, after all, the moons tidal torque that causes
the earth's surface to rotate 1 day less per year than its core. That
is a LOT of mass to drag around.

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://intlib.blogspot.com


		
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