From: Darin Sunley (rsunley@escape.ca)
Date: Wed Mar 01 2000 - 22:18:05 MST
Spike Jones <spike66@ibm.net> wrote:
>
>This isnt right tho. Remember in the rockets it is momentum that is
conserved
>not energy. Rockets are enormously wasteful of energy. If a skyhook
>existed, one could climb sufficiently high on it, then let go of the cable
>and fall into orbit. I just did a quick back of the envelope calc on that
>and it looks like if you climb one Earth diameter up the cable and let
>go, one would fall into a minimal orbit. And, if you had an elevator
>that could climb a stationary cable, the energy expenditure would
>be a fraction of that expended by a rocket.
>
True enough. Not to nitpick tho, but 1 earth diameter above the suface is a
heck of a lot higher then low earth orbit (as I understand it, 130-170 km).
It was my impression that if one wanted a reasonably circular orbit, the
only altitude one could jump into orbit from is the altitude of
goesynchronous orbit. With any lower altitude, you need a lot more sideways
velocity for a circular orbit then sitting at the top of a tower that tall
gives you.
Darin Sunley
rsunley@escape.ca
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