Velocity Analysis Using Separated Diffractions for Lunar Penetrating Radar Obtained by Yutu-2 Rover

Chao Li,Jinhai Zhang

doi:10.3390/rs13071387

Abstract

The high-frequency channel of lunar penetrating radar (LPR) onboard Yutu-2 rover successfully collected high quality data on the far side of the Moon, which provide a chance for us to detect the shallow subsurface structures and thickness of lunar regolith. However, traditional methods cannot obtain reliable dielectric permittivity model, especially in the presence of high mix between diffractions and reflections, which is essential for understanding and interpreting the composition of lunar subsurface materials. In this paper, we introduce an effective method to construct a reliable velocity model by separating diffractions from reflections and perform focusing analysis using separated diffractions. We first used the plane-wave destruction method to extract weak-energy diffractions interfered by strong reflections, and the LPR data are separated into two parts: diffractions and reflections. Then, we construct a macro-velocity model of lunar subsurface by focusing analysis on separated diffractions. Both the synthetic ground penetrating radar (GPR) and LPR data shows that the migration results of separated reflections have much clearer subsurface structures, compared with the migration results of un-separated data. Our results produce accurate velocity estimation, which is vital for high-precision migration; additionally, the accurate velocity estimation directly provides solid constraints on the dielectric permittivity at different depth.

Highlights

IntroductionIn the past half century, several radar detections have been carried out to study subsurface structures of the Moon, such as Earth based radar [1,2], orbital radar [3,4,5], and lunar penetrating radar (LPR) [6,7,8]
There are two channels of the lunar penetrating radar (LPR) payload: Channel 1 works with a central frequency of 60 MHz, which is to detect the deep subsurface structures with a resolution of 10 m within the depth of 500 m, and Channel 2 works with a central frequency of 500 MHz, which is to detect the shallow subsurface structures and lunar regolith with a resolution of 0.3 m within the depth of 50 m [6]
The diffractions are effectively with the separated diffractions, we find that the apexes of separated diffractions and small from the strong-energy reflections, and some weak-energy diffractions that are anomalies in eachseparated layer correspond to each other, which proves that the plane-wave destruction (PWD) method is hard to identify in the original ground penetrating radar (GPR) profile are successfully identified in the separated powerful on separating thethe reflections and results

Summary

Introduction

In the past half century, several radar detections have been carried out to study subsurface structures of the Moon, such as Earth based radar [1,2], orbital radar [3,4,5], and lunar penetrating radar (LPR) [6,7,8]. The LPR emits and receives the reflected high-frequency radar waves directly from the lunar subsurface anomalies, such as reflection layers and small diffractors, can detect local details of subsurface structures (Figure 1) [6]. Chang’E-3 landed in the Imbrium basin on the near side of the Moon in 2013, and the Yutu rover performed the first roving detection by LPR on an extraterrestrial planet [7]. The Yutu-2 rover was equipped with similar LPR payloads as the

Methods

Results

Conclusion