Tribocharging and electrical grounding of a drill in shadowed regions of the Moon

We present a first estimate of the triboelectric charging generated by a drill in Shackleton crater; a permanently shadowed region at the Moon’s south pole. The results depend upon the local plasma environment as well as material properties of the drill and lunar regolith. We show how in the dark plasma-poor regions, a high voltage can accumulate due to the negligible electrical grounding, leading to a potential hazard for explorers and their equipment. To mitigate this problem, two grounding solutions are described: (i) A sun-facing surface outside of the shadowed region and (ii) a portable UV ionization lamp. The two solutions are physically analogous, depleting charge by photo-ionization, and are predicted to both be relatively manageable to implement. We estimate the parameter requirements and discuss pros and cons for each method.