Simulation of the lunar dusty plasma exosphere interactions with a lunar lander

International audienceOne of the complicating factors of the future robotic and human lunar landing missions is the influence of the dust. The absence of an atmosphere on the Moon's surface is leading to the compaction and sintering of the dust particles found on the Moon surface. Properties of regolith as well as near-surface lunar exosphere depend on many factors, including the solar activity, lunar local time, position of the Moon relative to the Earth's magnetotail. The upper insulating regolith layer is electrically charging by photoelectron emission due to solar UV radiation and solar wind particles. Positive charge is created on the lunar illuminated side, while its night side is negatively charged. Charge distribution, and thus surface potential, depend on the lunar local time, latitude and the electrical properties of the regolith (the presence of water in the upper layer of the regolith, for example, might change the regolith electric conductivity). Understanding of mechanisms of the dust electric charging, dust levitation and Lander electric charging is essential for interpretation of measurements of two instruments: Dust Impact sensor and Langmuir Probe included in the forthcoming Luna-Glob lander mission what is under development now according to the Russian space program. One of the tools, which allows to simulate the dust emission from the Moon and asteroids, its transport, deposition and its interaction with a lander, is the SPIS-DUST (Spacecraft Plasma Interaction Software) code [1]. This paper presents first results of SPIS-DUST modelling of the interaction between the lunar exosphere, regolith and a lander. The model takes into account the geometry of the Luna-Glob lander, the electric properties of materials used on the lander surface, as well as Luna-Glob landing place. Initial conditions were chosen based on the current theoretical models of formation of dusty plasma exosphere and levitating charged dust particles. This paper is the first step in the cooperation between IKI, ESA, ONERA and LATMOS in frame of the Luna-Glob project on simulation of the lunar dusty plasma environment