[Cincinatus]

The sun pumps out a lot of He3 in the solar wind--which impacts and is trapped on the lunar surface.

True enough, except that not much 3He is present in the lunar soil -- the highest concentrations are on the order of one part per billion.

[Wonder Warthog]

"True enough, except that not much 3He is present in the lunar soil -- the highest concentrations are on the order of one part per billion."

Ah, but since fusion energy doesn't require a whole lot of mass, and the He3 is not strongly bound to the lunar soil, even a ppb level is economically feasible.