Ultraviolet and magnetic perspectives at Reiner Gamma and the implications for solar wind weathering

Abstract

With the wealth of missions selected to visit the lunar surface in the decade ahead, preparatory investigations into surface conditions are underway to explore potential challenges and science returns during these missions. One such mission, Lunar Vertex, is slated to explore a much-anticipated region–the lunar swirl and magnetic anomaly known as Reiner Gamma. Lunar swirls are unique natural laboratories for exploring solar wind interactions with partially magnetized rocky bodies, and possess characteristics that have not yet been observed on any other body in the Solar System. This work aims to combine current magnetic mapping of Reiner Gamma with ultraviolet wavelength datasets, towards further understanding the sensitivities of ultraviolet measurements in regions that may be partially magnetically shielded from solar wind weathering and magnetospheric plasma populations. Observations and models herein are collected and derived from orbital sources and will be used for comparison to future orbital and surface observations of Reiner Gamma by Lunar Vertex.

Extended Silicic Volcanism in the Gruithuisen Region—Revisiting the Composition and Thermophysical Properties of Gruithuisen Domes on the Moon

“…The magnetic field strength data (Richmond & Hood 2008;Ravat et al 2020) indicates the presence of a weak magnetic field to the north of the domes (Figure 14). The surface field model shown here is downward continued from orbital data and represents a lower bound on the possible surface field strength (e.g., Waller et al 2022). Several studies (e.g., Kramer et al 2011;Li & Garrick-Bethell 2019) indicate that regions with strong magnetic field display a depletion in OH and reduction in equilibrium of water abundance.…”

Lunar Magnetic Anomalies and Polar Ice

“…The low angle of solar wind incidence relative to the horizontal near the lunar poles should significantly improve the effectiveness of the south polar anomalies in shielding the underlying terrain from the solar wind ion bombardment. The Reiner Gamma anomaly deflects much of the solar wind ion bombardment, which is a major part of the explanation for its correlated higher‐albedo swirl markings (e.g., Kramer, Besse, et al., 2011; Kramer, Combe, et al., 2011; Glotch et al., 2015; for a recent summary of alternative explanations and why solar wind deflection is currently considered as the primary formation mechanism, see Waller et al., 2022, their Section 1.2). The angle of solar wind incidence at Reiner Gamma ranges from nearly grazing to nearly vertical depending on the time of the lunar day.…”