Solar Wind Interaction with Lunar Magnetic Anomalies: Vertical vs. Horizontal Dipole
Résumé
A detailed understanding of the solar wind interac- tion with lunar magnetic anomalies (LMAs) is essen- tial to identify its implications for both robotic and human exploration and to enhance our physical under- standing of the particle dynamics in partially and/or fully magnetized plasmas. We present three- dimensional full-kinetic and electromagnetic simula- tions of the solar wind interaction with both a vertical and a horizontal dipole model, resembling a medium- size LMA. We find that, in contrast to a horizontal dipole, a vertical dipole twists its field lines and cannot form a mini-magnetosphere. Instead, it creates a ring- shaped weathering pattern and reflects up to 21% of the incoming solar wind ions, that is ~4 times more than the horizontal case. We deliver hereby a vital piece to fully comprehend and interpret lunar observa- tions as we find the amount of reflected ions to be a tracer for the underlying field structure. Observing more reflected ions, however, does not necessarily point to the existence of a (larger) density cavity.
This work was supported by NASA’s SSSERVI/IMPACT and by the Swedish National Space Board, Grant No. 136/11. Resources supporting this work were provided by the NASA High-End Computing (HEC) Program through the NASA Ad- vanced Supercomputing (NAS) Division at Ames Re- search Center. Test simulations utilized the Janus su- percomputer, supported by NSF (CNS-0821794) and CU Boulder.