Solar wind interation with magnetic anomalies at the Moon and signatures from spectral imaging

Abstract:

Ever since the Apollo era, a question has remained as to the origin of the lunar swirls (high albedo regions coincident with the regions of surface magnetization). Different processes have been proposed for their origin. In this work we test the idea that the lunar swirls have a higher albedo relative to surrounding regions because they deflect incoming solar wind particles that can darken, or weather, the surface. Particle tracking is used to estimate the influence of four lunar magnetic anomalies on incoming solar wind. The regions investigated include Mare Ingenii, Gerasimovich, Renier Gamma and Northwest of Apollo. Both ions and electrons are tracked as they interact with the anomalous magnetic field and impact maps are calculated. The impact maps are then compared to optical observations and comparisons are made between the maxima and minima in surface fluxes and the high and low albedo regions. Results show deflection of typical solar wind particles on a larger scale than the fine scale optical features. Efficiencies for deflection of incoming particles do not scale directly with surface magnetic field strength but are also a function of the 3D nature of the magnetic field. All anomalous regions can also produce moderate deflection of fast solar wind particles but none can deflect SEP energy range particles.