Lunar magnetic fields: Implications for utilization and resource extraction

Abstract

Although the Moon possesses no large‐scale intrinsic magnetic field, locally strong crustal fields exist which must be considered in assessing lunar utilization scenarios. On the basis of available data, orbital anomalies most probably imply the presence of subsurface concentrations of metallic iron in the single‐domain size range. Such concentrations may indicate larger iron volume fractions than are characteristic of sampled materials, allowing more efficient extraction of metal than is now considered likely using nominal regolith compositions. Most other implications relate to the deflection of interplanetary and magnetospheric ions by crustal fields. Numerical simulations are employed to show that solar wind ion deflection by strong lunar magnetic anomalies can produce local increases, as well as decreases, in the implantation rate of solar wind hydrogen. The largest concentrations of implanted solar wind volatiles may therefore be found in local areas near strong anomalies. If water ice exists in permanently shadowed regions of the lunar poles, locally strong magnetic fields can shield these volatiles from sputter erosion losses by interplanetary and magnetospheric ion fluxes. Model simulations indicate that the ability of magnetic anomalies to shield the surface from incident ions increases with the angle of incidence and hence for most particle sources, with selenographic latitude. Finally, the possibility that relatively strong anomalies can provide significant protection of men and materials against major solar flare particle events is examined and found to be unlikely.