Space weathering on Mercury Original Research Article

Space weathering is a process where formation of nanophase iron particles causes darkening of overall reflectance, spectral reddening, and weakening of absorption bands on atmosphereless bodies such as the moon and asteroids. Using pulse laser irradiation, formation of nanophase iron particles by micrometeorite impact heating is simulated. Although Mercurian surface is poor in iron and rich in anorthite, microscopic process of nanophase iron particle formation can take place on Mercury. On the other hand, growth of nanophase iron particles through Ostwald ripening or repetitive dust impacts would moderate the weathering degree. Future MESSENGER and BepiColombo mission will unveil space weathering on Mercury through multispectral imaging observations.