Lunar Precursor Effects Observed by ARTEMIS in the Solar Wind and Magnetosphere

The Moon to first order acts as a simple absorber of plasma, resulting in a downstream wake in flowing plasma, and charging of the surface in response to incident currents. However, recent data from several missions have shown that some effects of the Moon can be observed at large distances from its surface, at some times even in the upstream direction. We present observations of a variety of lunar precursor effects observed by the new two-probe ARTEMIS mission, which achieved lunar orbit insertion in June/July 2011. In the terrestrial magnetosphere, we observe magnetically reflected electrons (forming a loss cone distribution) and electrostatically accelerated secondary/photo electron beams that can travel very large distances from the lunar surface, producing a variety of waves in both the whistler and Langmuir range. In the solar wind, with a more significant ambient density and flow, upstream effects are more muted, but still present. Both ions and electrons can be reflected and/or produced at the dayside surface, feeding back into the upstream plasma environment and producing waves capable of affecting the ambient environment.