Assessment of the Shielding Effect of the Earth's Magnetic Field on Lunar OH/H2O

Abstract

AbstractWhen the Moon passes through Earth's magnetosphere, it is believed that the amount of OH/H2O that would typically be created is reduced because the incident solar wind flux on the lunar surface decreases. To confirm this, we analyzed changes in OH/H2O absorption feature in the infrared region with or without the shielding effect of the magnetosphere using Moon Mineralogy Mapper (M3) data in low‐latitude regions. We report that the strength of absorption feature near 3 μm for the region from the equator up to the 10° latitude decreased when the Moon is inside Earth's magnetosphere relative to when it was outside of it. This indicates that the amount of OH/H2O on the shielded surface is less than on the unshielded surface. We confirmed that Earth's magnetosphere affects the OH/H2O distribution at low‐latitude regions, so the OH/H2O on the surface is originated by solar wind implantation. However, this study includes certain level of uncertainties in thermal corrections, and thus, sophisticated additional attempts are needed.