[extropy-chat] Space elevator numbers III

[Eugen Leitl]

On Thu, Feb 15, 2007 at 09:27:26PM -0800, spike wrote:

> More later on this, but the issue with a lunar synchronous cable is related
> to the moon having a tragically slow rotation rate.  The earth is in lunar
> synchronous orbit, if you want to think of it that way.  If you calculate
> the length of the cable to either lagrangian points 1 or 2, the cable needs
> to be crazy long.  Technically it is easier than an earth synchronous cable,

Not nearly as long as the Earth tether, which is, what, 100000 km?

http://en.wikipedia.org/wiki/Lunar_space_elevator
says a tether from M5 fiber would 6100 tons, including a massive counterweight.

> but it doesn't have much use methinks.
> 
> spike
> 
> PS I spent way too much of my spare time on this trip trying to figure out
> why Kieth's idea of uranium solution transmutation wouldn't work.  I have a
> sick feeling in my gut that it would work.  Which means any sophisticated
> chemist could make purified plutonium in her basement lab using readily

Any chemical-technical assistant, actually. Or an undergrad. You probably
don't even need a hot cell.

> available materials, oy freaking vey.

Except for a nuclear reactor, that's not so easily available. 
I don't think thorium is nearly as regulated as enrichened uranium,
so that might be a loop hole. You'd need many tons of thorium, though,
and cooling the assembly would take more than a small creek.
A deep cave with running water would do fine, because runoff would have
time to cool so you won't see it as a hot spot from orbit.

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