Solar wind precipitation on atmosphere-less bodies like the Moon generates backscattered and sputtered energetic neutral atoms (ENAs) from the surface. Since ENAs does not sense electromagnetic fields, ENAs can be assumed to retain the initial velocity if gravity effect can be ignored. This makes remote sensing of surface properties and near-surface plasma conditions possible from a spacecraft orbit. Lunar Neutrals Telescope (LNT) is an ENA instrument on the first Turkish Lunar Mission. LNT is tailored to answer several fundamental scientific questions. Three scientific objectives are set: (1) To search for volatile-rich areas on the surface including permanently shadowed regions, (2) to investigate the structure of mini- magnetosphere created by lunar magnetic anomalies and its response to the solar wind, and (3) to investigate the formation and maintenance processes of the lunar exosphere. We will present LNT scientific objectives as well as a brief description of the instrument.

Volatiles and refractories represent the two end-members in the volatility range of species in any surface-bounded exosphere. Volatiles include elements that do not interact strongly with the surface, such as neon (detected on the Moon) and helium (detected both on the Moon and at Mercury), but also argon, a noble gas (detected on the Moon) that surprisingly adsorbs at the cold lunar nighttime surface. Refractories include species such as calcium, magnesium, iron, and aluminum, all of which have very strong bonds with the lunar surface and thus need energetic processes to be ejected into the exosphere. Here we focus on the properties of species that have been detected in the exospheres of inner Solar System bodies, specifically the Moon and Mercury, and how they provide important information to understand source and loss processes of these exospheres, as well as their dependence on variations in external drivers.