The Influence of Space Weathering on the Reflectance Spectra of Silicate Asteroids

Research on space weathering is of great significance for the remote sensing inversion of the surface environment and composition of asteroids. Currently, the research results on the spectral changes of asteroids caused by space weathering are not consistent, and there is a lack of systematic understanding of the weathering models of silicate asteroids. In this study, based on the idea of large-sample research, laser irradiation experiments were conducted on 4 ordinary chondrites (H, L, and LL types), 7 types of silicate minerals, and 6 groups of olivine-pyroxene mixtures with different proportions. The visible-near-infrared reflectance spectra (0.45--2.5μm) of the samples before and after laser experiments were analyzed, and the impact of space weathering on the reflectance spectra of silicate asteroids was studied in combination with the spectral classification of asteroids. Our results showed that space weathering can increase the band area ratio, but it does not cause a significant shift in the 1μm absorption center. The use of the ``1μm absorption center - band area ratio'' diagram is still effective in distinguishing different types of meteorites. Moreover, space weathering has little impact on overall mineralogical classification. In the principal component analysis plot, A-type asteroids have a space weathering trend almost parallel to the α line, while the rest of the silicate asteroids have a ``Q-Sq-S'' space weathering trend. The asteroid classification system based on Sloan Digital Sky Survey (SDSS) data may confuse the classification of olivine-rich asteroids and may underestimate the number of A-type asteroids. This study systematically analyzed the weathering models and spectral changes of silicate asteroids, which is scientifically significant for a better understanding of the space weathering effect on asteroid spectra and has practical value for remote sensing quantitative inversion.