In situ spectral measurements of space weathering by Chang'e-4 rover

Space weathering introduces confounding effects on visible and near infrared reflectance spectra of airless bodies, which considerably darkens the reflectance, reddens the continuum slope and suppresses absorption features. It's mainly attributed to the gradual formation and accumulation of submicroscopic metallic iron (SMFe) on regolith grains. In situ spectral measurements from Chang'e-4 rover provide a unique opportunity to investigate the space weathering effects on the intact lunar farside regolith. SMFe abundance at the landing site, which is 0.32 +/- 0.06wt.%, is retrieved from in situ measured reflectance spectra by using Hapke model. The derived Is/FeO maturity index (82 +/- 15) indicates the Finsen crater ejecta-sourced regolith is mature, which is consistent with the geologic background that it had experienced about 3.7 Ga space weathering. (C) 2020 Elsevier B.V. All rights reserved.