Research of the Optical Effects of Space Weathering on Lunar Regolith Based on the Nonlinear Mixing Model

The reflectance spectrum of lunar soil is mainly dominated by its composition and the degree of exposure to space weathering processes such as micrometeorite bombardment and solar wind implantation. The spectral alteration effects of space weathering should be removed for accurately investigating the composition of the lunar surface using remote sensing data. It can contribute to develop the method for decoupling the spectral effects of composition and maturity to improve the inversion accuracy by exploring the optical effects of space weathering on lunar regolith. Because unweathered soil is hard to acquire, it's unable to compare the spectra between the weathered and unweathered soil directly. This paper provided a simple way to investigate the optical effects of space weathering. First, the mixed spectra is acquired according to the mineral contents and spectra measured from the lunar soil using the Hapke model. Then the modeled spectra of lunar soil were compared with the real spectra measured by Brown University. Investigation results showed that the space weathering can reduce the overall reflectance of lunar soil, and the shorter waveband the greater reducing; that it can increase the continuum slope to the spectrum, which makes the spectra redder; and it can also reduce the absorption depth and spectral contrast, and the absorption peak near 2.0μm was reduced more than that near 1.0μm. These factors should be taken into consideration when the element contents are retrieved using remote sensing technology.