In situ optical measurements of Chang'E-3 landing site in Mare Imbrium: 2. Photometric properties of the regolith

Abstract

The panorama cameras onboard the Yutu Rover of the Chang'E‐3 lunar mission acquired hundreds of high‐resolution color images of the lunar surface and captured the first in situ lunar opposition effect (OE) since the Apollo era. We extracted the phase curve and the color ratio in three bands with the phase angle range from 2° to 141°. Photometric inversions using the Hapke model reveal that submicroscopic dusts are present in the landing area and both the coherent backscattering and the shadow hiding are responsible for the strong OE. Compared with spaceborne measurements, the grains in the landing site are brighter, more transparent, and appear to be better crystallized than the average maria basaltic grains. The results show that the phase‐reddening effect appears to be present in the in situ phase curves. The current phase curve can be used as the ground‐truth validations of any future spaceborne phase curve measurement over the landing site region.

The role of substrate characteristics in producing anomalously young crater retention ages in volcanic deposits on the Moon: Morphology, topography, subresolution roughness, and mode of emplacement of the Sosigenes lunar irregular mare patch

“…For all the surfaces of different morphologic units, their radiance factor values in the larger‐α image are systematically lower than those in the smaller‐α image, which is consistent with the ubiquitous trend of decreasing brightness with increasing phase angle (e.g., Hapke ; Jin et al. ).…”

Weak Dust Activity Near a Geologically Young Surface Revealed by Chang'E‐3 Mission

“…In order to reduce the impact of different gains and exposure times of multiple images on the bidirectional reflectance extraction, the DN values in each L2B frame we choose are divided by the working normalized parameter, A Cali , recorded in the header file, to normalize the brightness. Then using the absolute radiation calibration coefficients measured in the preflight calibration experiments, we convert the DN values in each frame to radiance, I , as where C Rad represents the absolute radiation calibration coefficient (Jin et al, ). It equals 5.9365×10 5 Sr·nm·m 2 ·W −1 for the red band with center wavelength 640 nm, 5.1837×10 5 Sr·nm·m 2 ·W −1 for the blue band with center wavelength 470 nm, and 5.9796×10 5 and 5.8939×10 5 Sr·nm·m 2 ·W −1 for the first and second green bands with center wavelength 540 nm, respectively.…”

“…Photometric measurements usually focus on the phase curve from which physical properties of lunar regolith can be retrieved (Hapke, ; Hapke et al, ; Jin et al, ). Based on the distinct reflectance features between lunar regolith and rocks discussed below, we propose a new method to survey the long‐term dust activity on the geologically young surface and report probable new in situ dust electrostatic transport observations from Chang'E‐3 (CE‐3) mission.…”

Phase Functions of Typical Lunar Surface Minerals Derived for the Hapke Model and Implications for Visible to Near‐Infrared Spectral Unmixing

“…The formulation of the radiative transfer theory derived by Hapke (), hereafter referred to as the Hapke model, is widely used in estimating mineralogical and chemical information from reflectance spectra in the visible (VIS) to near‐infrared (NIR) wavelength region (e.g., Denevi et al, ; Jin et al, ; Li & Milliken, ; Lucey, ; Mustard & Pieters, ; Sato et al, ). This semi‐empirical model expresses reflectance as a function of single‐scattering albedo (SSA), viewing geometry, illumination angle, opposition effect, single particle scattering phase function (PF), multiple scattering, and surface roughness (e.g., Hapke, , ).…”