The fact that bombarding lithium with neutrons produces tritium that decays into helium 3 (this reaction is actually responsible for a good fraction of the yield of many fusion warheads, see Castle Bravo). And the helium 3 on the moon is A - on the moon, B - of such a low concentration that the total thermal energy possible to get from fusion of absolutely all the He3 present per cubic meter of the top foot or so of lunar soil is about a quarter that of the worst lignite coal on Earth. And lignite requires a hell of a lot less energy and infrastructure per unit mass to process. By my calculations, given the heat capacity of the minerals it has been blasted into by the solar wind, you need to use at least half that energy on site just to heat the rocks to the point it gets driven off as a vapor. Then there's all the movement of mass, purifying it down non-terrestrially from all kinds of other vapor, ridiculous launch costs... its not happening.
I've seen claims in several internet sources, a video documentary and the Wikipedia article that some countries have had plans to mine helium-3 on the moon. I wonder if the reporting is incompetent or if the plans are made by incompetent optimists if what you're saying is true. How did this meme originate?
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