Prospecting for lunar 3He with a radio-frequency atomic magnetometer

Mining 3He from lunar regolith has attracted significant interest in recent years due to the scarcity of 3He on Earth and its diverse applications, from cryogenics and medical imaging, to nuclear physics and future nuclear fusion. Given the stringent technical and economic challenges of mining lunar 3He, precise prospecting is essential. Here, we propose a prospecting methodology based on a radio-frequency atomic magnetometer, which can detect the dipolar magnetic field of thermally polarized 3He spins. With a 200 g regolith sample and an rf magnetometer with sensitivity 1fT/Hz, we can detect 3He with abundance 5 ppb within a measurement time of just 5 min. The associated apparatus is lightweight and significantly more cost-effective than alternative measurement techniques. The proposed prospecting method is readily deployable and could substantially improve the technical and economic feasibility of mining lunar 3He.