Abstract
On January 3rd 2019, the Chang’e-4 mission successfully landed in the Von Kármán Crater inside the South Pole-Aitken (SPA) basin and achieved the first soft landing on the farside of the Moon. Lunar penetrating radar (LPR) equipped on the rover measured the shallow subsurface structure along the motion path for more than 700 m. LPR data could be used to obtain the dielectric properties of the materials beneath the exploration area, providing important clues as to the composition and source of the materials. Although the properties of the upper fine-grained regolith have been studied using various methods, the underlying coarse-grained materials still lack investigation. Therefore, this paper intends to estimate the loss tangent of the coarse-grained materials at depth ranges of ~12 and ~28 m. Stochastic media models with different rock distributions for the LPR finite-difference time-domain (FDTD) simulation are built to evaluate the feasibility of the estimation method. Our results show that the average loss tangent value of coarse-grained materials is 0.0104±0.0027, and the abundance of FeOT+TiO2 is 20.08 wt.%, which is much higher than the overlying fine-grained regolith, indicating different sources.
Highlights
Verify the The correctness of the loss tangent estimation method, which ismethod mentioned in Section the correctness of the loss tangent estimation method, which is mentioned in Section gprMax software, an open source software package for numerical modeling of ground 2.2
It is foreseeable that the reflection signal of the buried rock and the multiple scattering signals among the rocks will affect signal of the buried rock and the multiple scattering signals among the rocks will affect the results of the loss tangent estimation, so three models are used in this experiment to the resultsthe of influence the loss tangent so three media models are used this for experiment to evaluate of rocks.estimation, The base stochastic model is theinsame these evaluate the influence of rocks
The simulation results demonstrate that the estimation is close to the real setting when the propagation medium is uniform with little scattering, and the error is about 15%
Summary
Academic Editors: Lin Li, Yuanzhi Zhang and Shengbo Chen. Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. In January 2019, the Chang’e-4 lander successfully landed in the Von Kármán Crater on the lunar farside, becoming the first probe to land on the farside of the moon. The Yutu-2 rover is equipped with instruments including a multi-antenna, two channels (channel one and two) lunar penetrating radar (LPR) system. Yutu-2 rover during the the firstfirst fifteen lunar days. TheisLROC (Robinson et et al., 2010) Narrow-Angle Camera (NAC) image of the. ID: M134022629LE, al., 2010) Narrow-Angle Camera (NAC) image of the Yutu-2 rover’s surveying area 1.27m/pixel, 77.55° incidence angle) [4].[4].
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