Solar Wind Interaction with Lunar Magnetic Fields: ARTEMIS Observations and Correlations with Surface Properties

Friday, 19 December 2014
Jasper S Halekas, University of Iowa, Physics and Astronomy, Iowa City, IA, United States, David T Blewett, JHU Applied Physics Lab, Laurel, MD, United States, Andrew R Poppe, University of California, El Cerrito, CA, United States and Dave A Brain, Laboratory for Atmospheric and Space Physics, Boulder, CO, United States
Lunar magnetic fields, though small in scale and comparatively weak, have surprisingly significant effects on the incoming plasma, and a number of observations suggest that their presence may locally alter the space weathering of the surface. Recent observations from Kaguya and Chandrayaan have shown that lunar magnetic anomalies efficiently reflect incoming solar wind protons, providing substantial shielding of portions of the crust, with potential implications for both space weathering and surface sputtering. The two ARTEMIS probes have made a number of low-altitude (tens of kilometers) passes over regions with moderately strong crustal magnetic fields, at local times both near the sub-solar point and at the terminator. Several such passes occurred over a region of the surface containing unusual albedo markings - or "swirls" - that could indicate a local reduction in space weathering. We investigate the ARTEMIS low-altitude passes in detail, focusing on how the observed reflected protons and other local modifications of charged particle distributions and electromagnetic fields relate to the properties of the surface.