Re: Towers to the stars

From: Spike Jones (
Date: Tue Mar 07 2000 - 18:52:51 MST

Jeff Davis wrote:

> So I puzzled over it for a week, and found no flaw in spike's reasoning,
> or, to be more precise, no flaw in his conclusion. Quite elegant, actually.
> ...
> According to Kepler and Newton all planetary orbits are elliptical (a...
> the earth at the other end is the perigee. Nifty.

Jeffer, I must explain myself. I went down that exact line of reasoning
when I first posted, then the flaw occurred to me while I was off calcing
another nifty idea, so I created a diversion [which resulted in the
thread with the unfortunate name english schminglish] to stall for time
while I worked out my other idea, then returned to this. My other
idea is working out really cool! But this one has languished, like my
information game notion. {8-[

The problem with the eliptical orbit notion, jumping off the tower
at one earth diameter from the surface of the planet is that one's
tangential velocity at three planet radii from the one focus is a
function of the sidereal rotation rate of the planet. So I can
immediately give you one case where the idea wont work: where
the rotation rate of the planet is zero with respect to the stars.
[Ignore for just a moment that no isosynchronous tower would
be possible under those conditions.] With zero sidereal motion,
one could be 3 radii out [or arbitrarily many radii out] leap off
the tower and one would fall straight down, with unfortunate

Another counterexample is if the sidereal rate is really fast, so
that isosynchronous altitude is lower than a planet diameter
from the surface. You step off of that and shhhhooooom!
You might never be heard from again. {8-]

Nowthen, please be patient with me and I will finish my other
still cooler idea, and share it with the group. Or Doug Jones
will carry the ball.

In the mean time I have a little gift here for you space cable
fans. Robert B. and I have been offlisting about it. Its a
spreadsheet that calcs the total mass of an isosynchronous
space cable as a function of the rotation rate of the planet,
the mass of the planet, the material properties orf the cable, etc.
I wrote it about 13 yrs ago, then put it in a tech paper in 93.

I dont think I can post an enclosure on extropians, so if you
are interested in it, offlist me. spike

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