Lunar Mineral Abundance Inversion of Sinus Iridum Considering Space Weathering Effect

The inversion of lunar minerals is critical to study the Moon's geological origin and evolution. Space weathering generally occurs on the surface of the Moon with an assignable influence on the pure mineral spectra, which obscures the reflectance spectra feature of minerals and reduces the overall reflectance. The effect of space weathering should be removed when accurately investigating the lunar minerals using remote sensing technology. The level of the space weathering is proportional to the mass fraction of submicroscopic metallic iron (SMFe). In this paper, the authors firstly transform the bidirectional reflectance into the isotropic single scattering albedo of four endmember minerals (clinopyroxene, orthopyroxene, plagioclase and olivine) in the Relab spectral library based on Hapke radiative transfer model, secondly, calculate the optical constants and absorption coefficient of each mineral, then simulate the reflectance spectra of these minerals under six space weathering levels according to SMFe mass fraction, thus we obtain endmember mineral reflectance under different space weathering levels. Finally we inverse mineral abundance with six multi-endmember linear unmixing models and the M³ (moon mineralogy mapper) hyperspectral data and obtain the inversion abundance and distribution of pyroxene, plagioclase and olivine in Lunar Sinus Iridum. The results show that using multi-endmember linear unmixing method can effectively simulate the effects of space weathering on mineral spectra, and it is an useful way of mineral identification and abundance inversion with hyperspectral under the space weathering.