SELMA mission: How do airless bodies interact with space environment? The Moon as an accessible laboratory

The Moon is an archetypal atmosphere-less celestial body in the Solar System. For such bodies, 38 the environments are characterized by complex interaction among the space plasma, tenuous 39 neutral gas, dust and the outermost layer of the surface. Here we propose the SELMA mission 40 (Surface, Environment, and Lunar Magnetic Anomalies) to study how airless bodies interact with 41 space environment. SELMA uses a unique combination of remote sensing via ultraviolet and 42 infrared wavelengths, and energetic neutral atom imaging, as well as in situ measurements of 43 exospheric gas, plasma, and dust at the Moon. After observations in a lunar orbit for one year, 44 SELMA will conduct an impact experiment to investigate volatile content in the soil of the 45 permanently shadowed area of the Shackleton crater. SELMA also carries an impact probe to
46 sound the Reiner-Gamma mini-magnetosphere and its interaction with the lunar regolith from the 47 SELMA orbit down to the surface. SELMA was proposed to the European Space Agency as a 48 medium-class mission (M5) in October 2016. Research on the SELMA scientific themes is of 49 importance for fundamental planetary sciences and for our general understanding of how the 50 Solar System works. In addition, SELMA outcomes will contribute to future lunar explorations 51 through qualitative characterization of the lunar environment and, in particular, investigation of 52 the presence of water in the lunar soil, as a valuable resource to harvest from the lunar regolith.