Abstract The Chang’e-6 (CE-6) mission returned a lunar sample from the farside of the Moon for the first time. The Lunar Mineral Spectrometer (LMS) onboard the CE-6 Lander successfully acquired in situ multiangle spectral data of the sampling area, providing a valuable opportunity to study the photometric characteristics of the lunar farside regolith. Combined with terrain-corrected observational geometry, this study investigates the scattering properties of the CE-6 sampling area by applying Hapke’s radiative transfer model to 11 band near-infrared and shortwave infrared data of LMS. The results indicate that the CE-6 regolith exhibits back-scattering characteristics, in contrast to the forward-scattering behavior observed in situ by the Chang’e-5 (CE-5) mission on the lunar nearside. By comparing the mineral composition and microstructures of the returned lunar samples from CE-5 and CE-6, we found that this difference can be attributed to several factors: (1) a higher abundance of high-albedo minerals and exogenous ejecta materials in CE-6 soils; (2) more complex surface morphology and increased density of internal scatterer of CE-6 soil grains; and (3) a higher porosity of CE-6 bulk soils. This study not only deepens our understanding of the physical mechanisms regarding the lunar soil scattering behaviors but also provides new in situ observational evidence for interpreting the photometric characteristics of the lunar farside regolith.
Tian et al. (Tue,) studied this question.