SPRG Seminars
August 30, 2011:
" Lunar precursor effects observed by Lunar Prospector and ARTEMIS "
Jasper Halekas, Space Science Laboratory, University of California at Berkeley
The Moon has commonly been thought to provide a relatively simple obstacle to incident plasma, with charged particles absorbed at the surface and a plasma depletion or wake formed in the anti-flow direction (if the plasma has a prevailing flow). However, recent simulations and observations indicate that the Moon may in fact significantly affect the surrounding plasma, including in the upstream direction. This occurs at the most basic level because a portion of each plasma population is removed by the lunar obstacle, naturally creating non-equilibrium distribution functions. However, the Moon also provides a natural source of both reflected and secondary charged particle populations, which feed back on the ambient plasma environment. I will present observations from both Lunar Prospector and ARTEMIS showing a variety of lunar precursor effects involving both electron and ion populations.