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Date:      Mon, 25 Aug 1997 18:53:26 -0600 (MDT)
From:      Wes Peters - Softweyr LLC <softweyr@xmission.com>
To:        mike@smith.net.au (Mike Smith)
Cc:        chat@freebsd.org
Subject:   Re: Anarchists decry 72lbs plutonium launc
Message-ID:  <199708260053.SAA08910@xmission.xmission.com>
In-Reply-To: <199708250412.NAA01430@word.smith.net.au> from "Mike Smith" at Aug 25, 97 01:42:44 pm

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> > PS: any takers on a guess as to whether or not 72lbs is over critical
> > mass for Plutonium?

That would depend on the purity of the plutonium, now wouldn't it?
I was once told by somebody who probably knows that with weapons-
grade material, you could get a chain reaction with less than a
mole of plutonium.  He didn't say which isotope this needed to be.

> My understanding (Brian Handy, are you listening here?) is that the 
> plutonium is used as a heat source to provide electrical power.  I have 
> a hard time imagining 30+ kilos of the stuff being required for 
> anything on the scale of a satellite.

It depends on the power budget and lifetime of the satellite.  These
devices, once known as SNAP generators, are about as bone-head simple
as you can get: a bottle of low-grade plutonium straight out of the
garbage bins at Rocky Flats, wrapped with thermocouple wires.  They
produce little power, but don't decay (that 50,000 yr half-life).
If you've got nice, big boosters to get them out of Earth's gravity
well, they're a reliable cheap source of power out beyond the gravel
patch (planetary disk).


-- 
          "Where am I, and what am I doing in this handbasket?"

Wes Peters                                                       Softweyr LLC
http://www.xmission.com/~softweyr                       softweyr@xmission.com



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