Space weathering simulation and spectrum decoding

Visible and near-infrared spectra are routinely used to achieve mineral abundances and mineral chemistry of the global surfaces of the Moon and asteroids.However,these spectra can be significantly modified by space weathering,including micrometeorite impacting,solar wind implanting and cosmic ray irradiation.In this paper we report results of laser-bombarding experiments on the Jilin ordinary chondrite,simulating micrometeorite impacting on the surface of asteroids.After laser bombardment,the spectra became significantly redder and moderately darker.With the Modified Gaussian Model (MGM) method,the absorption band positions of olivine can be decoded from the modified spectra,which are correlated with their fayalite contents.In addition,a continuum of the modified spectra can be decoded,and its slope may be used to depict the degree of space weathering,However,relative strengths of the absorption sub-bands of olivine and pyroxenes show significant variant after the bombardment,hence they cannot be used to estimate the relative abundances of high-Ca to low-Ca pyroxenes of the lunar surface and other matured surfaces of asteroids.