In situ lunar phase curves measured by Chang’E-4 in the Von Kármán Crater, South Pole-Aitken basin
Te Jiang, Xiaoyi Hu, Hao Zhang, Pei Ma, Chunlai Li, Xin Ren, Bin Liu, Dawei Liu, Jianfeng Yang, Bin Xue, W. Jin, Meng‐Hua Zhu, Changning Huang, Hongyu Lin
Abstract
Context. The Yutu-2 rover of the Chang’E-4 (CE-4) mission measured the lunar phase curves in the Von Kármán crater, South Pole-Aitken basin. Aims. We aim to study the photometric properties of the regolith at CE-4’s landing site and compare them with those of Chang’E-3 (CE-3) in order to understand the regolith physical properties of the two landing sites. Methods. We extracted the insitu lunar phase curves measured by CE-4 with a very wide phase angle coverage (1°–144°) and performed photometric model inversions using both the Hapke model and the Lumme-Bowell model. Results. Compared with the CE-3 measurement taken in Mare Imbrium, the CE-4 phase curves show the colorimetric opposition effect and have a steeper and narrower opposition spike. The surface regolith at the CE-4 site is much darker, more porous, more forward scattering, and has a larger slope angle (Hapke model) than that of CE-3. Conclusions. The CE-4 site may have experienced more space weathering alterations than the CE-3 site, which is consistent with their different surface model ages (~3.6 Ga for CE-4 and ~3 Ga for CE-3).