[freebeard]

Helium-3 comes from the solar wind. 'Real' helium is helium-4.

https://ocw.mit.edu/courses/nuclear-...um3_fusion.pdf

Without a repulsive atmosphere, the moon has accumulated large amounts of helium-3 on its surface. An interesting statistic is that the amount of energy stored in lunar helium is 10 times the amount of energy stored in all of the fossil fuels on earth. Because the lunar helium-3 exists in concentrations of 13 parts per billion in the lunar soil, a significant amount of refining would need to occur on the moon in order to extract the helium-3 and maximize the amount that could be returned to earth on each trip.
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Helium-3 fusion is definitely a far distance away and should best be considered as a second generation fuel, something that may be exploited after current methods for confinement have been refined to the commercial reactor level. Nevertheless, helium-3's benefits in terms of energy conversion and radioactivity are significant, and should be further explored. Clearly mining the moon is a crazy idea; however, the technology could be is a crazy idea; however, the technology could be developed to make it a possibility.