DIETZ@slb-test.CSNET ("Paul F. Dietz") (11/12/86)
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.