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From: DIETZ@slb-test.CSNET ("Paul F. Dietz")
Newsgroups: sci.space
Subject: Lunar He-3
Message-ID: <8611120617.AA02138@s1-b.arpa>
Date: Tue, 11-Nov-86 16:58:00 EST
Article-I.D.: s1-b.8611120617.AA02138
Posted: Tue Nov 11 16:58:00 1986
Date-Received: Wed, 12-Nov-86 20:14:44 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
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About concentrations of He-3 in lunar soil...

The concentration of helium ranges from 1 to 35 ppm, with 15 ppm being the
mean value for lunar maria soil.  The ratio of He-4 to He-3 ranges from
2200 to 3000.  Given those figures, the average concentration of He3 is
around 5 ppb.  One kilogram of He-3, currently worth $700,000 dollars,
would require the processing of 200,000 metric tons of soil, at a cost
of < $3.5/ton.

Note that at 50% efficiency and $.05/KWH, one gram of helium-3 can generate
$4100 worth of electricity.  Higher efficiencies may be possible.