Estimated solar wind-implanted helium-3 distribution on the Moon

Among the solar wind-implanted volatiles present in the lunar regolith, ³He is possibly the most valuable resource because of its potential as a fusion fuel. The abundance of ³He in the lunar regolith at a given location depends on surface maturity, the amount of solar wind fluence, and titanium content, because ilmenite (FeTiO₃) retains helium much better than other major lunar minerals. Surface maturity and TiO₂ maps from Clementine multispectral data sets are combined here with a solar wind fluence model to produce a ³He abundance map of the Moon. Comparison of the predicted ³He values to landing site observations shows good correlation. The highest ³He abundances occur in the farside maria (due to greater solar wind fluence received) and in higher TiO₂ nearside mare regions.