Lunar helium-3 mining for fusion energy
Helium-3 concentrations on the Moon are estimated to be up to 15 ppb in sunlit areas and as much as 50 ppb in permanently shadowed regions (e.g. possibly in areas already established for mining water ice). Compared to helium-3 sources in Earth’s atmosphere, the Moon has at least 1000x more accessible helium-3. Still, massive amounts of lunar regolith (dirt) would need to be processed (think hundreds of tons) to collect a measurable quantity (think grams).
By the late 2040s, lunar mining will be a critical source of water, propellant, and construction materials for now growing lunar-crew bases. The amount of resource processing may be of a scale to allow affordable supplemental mining of helium-3.
Why is this significant? Helium-3 has long been considered a possible non-radioactive, safe fuel for more efficient nuclear fusion than that achievable with deuterium and tritium. Not only would this be a boon for lunar power, helium-3 becomes a valuable lunar export with the expected accomplishment of nuclear fusion power plants.