scholarly journals Properties Analysis of Lunar Regolith at Chang’E-4 Landing Site Based on 3D Velocity Spectrum of Lunar Penetrating Radar

2020 ◽  
Vol 12 (4) ◽  
pp. 629 ◽  
Author(s):  
Zejun Dong ◽  
Xuan Feng ◽  
Haoqiu Zhou ◽  
Cai Liu ◽  
Zhaofa Zeng ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
Lunar Regolith ◽  
Landing Site ◽  
Threshold Function ◽  
Velocity Spectrum ◽  
Maximum Relative Error ◽  
Soft Landing ◽  
Average Maximum ◽  
Effective Instrument ◽  
Moon Exploration

The Chinese Chang’E-4 mission for moon exploration has been successfully completed. The Chang’E-4 probe achieved the first-ever soft landing on the floor of Von Kármán crater (177.59°E, 45.46°S) of the South Pole-Aitken (SPA) basin on January 3, 2019. Yutu-2 rover is mounted with several scientific instruments including a lunar penetrating radar (LPR), which is an effective instrument to detect the lunar subsurface structure. During the interpretation of LPR data, subsurface velocity of electromagnetic waves is a vital parameter necessary for stratigraphic division and computing other properties. However, the methods in previous research on Chang’E-3 cannot perform velocity analysis automatically and objectively. In this paper, the 3D velocity spectrum is applied to property analysis of LPR data from Chang’E-4. The result shows that 3D velocity spectrum can automatically search for hyperbolas; the maximum value at velocity axis with a soft threshold function can provide the horizontal position, two-way reflected time and velocity of each hyperbola; the average maximum relative error of velocity is estimated to be 7.99%. Based on the estimated velocities of 30 hyperbolas, the structures of subsurface properties are obtained, including velocity, relative permittivity, density, and content of FeO and TiO2.

scholarly journals Rock Location and Property Analysis of Lunar Regolith at Chang’E-4 Landing Site Based on Local Correlation and Semblance Analysis

2020 ◽  
Vol 13 (1) ◽  
pp. 48
Author(s):  
Hanjie Song ◽  
Chao Li ◽  
Jinhai Zhang ◽  
Xing Wu ◽  
Yang Liu ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
Lunar Regolith ◽  
Landing Site ◽  
Rock Properties ◽  
The Moon ◽  
Local Correlation ◽  
Near Surface ◽  
Property Analysis ◽  
Stratigraphic Division ◽  
Formation And Evolution

The Lunar Penetrating Radar (LPR) onboard the Yutu-2 rover from China’s Chang’E-4 (CE-4) mission is used to probe the subsurface structure and the near-surface stratigraphic structure of the lunar regolith on the farside of the Moon. Structural analysis of regolith could provide abundant information on the formation and evolution of the Moon, in which the rock location and property analysis are the key procedures during the interpretation of LPR data. The subsurface velocity of electromagnetic waves is a vital parameter for stratigraphic division, rock location estimates, and calculating the rock properties in the interpretation of LPR data. In this paper, we propose a procedure that combines the regolith rock extraction technique based on local correlation between the two sets of LPR high-frequency channel data and the common offset semblance analysis to determine the velocity from LPR diffraction hyperbola. We consider the heterogeneity of the regolith and derive the relative permittivity distribution based on the rock extraction and semblance analysis. The numerical simulation results show that the procedure is able to obtain the high-precision position and properties of the rock. Furthermore, we apply this procedure to CE-4 LPR data and obtain preferable estimations of the rock locations and the properties of the lunar subsurface regolith.

scholarly journals Rock Location and Quantitative Analysis of Regolith at the Chang’e 3 Landing Site Based on Local Similarity Constraint

2019 ◽  
Vol 11 (5) ◽  
pp. 530 ◽  
Author(s):  
Bin Hu ◽  
Deli Wang ◽  
Ling Zhang ◽  
Zhaofa Zeng
Keyword(s):  
Quantitative Analysis ◽  
Lunar Regolith ◽  
Landing Site ◽  
Threshold Function ◽  
Local Similarity ◽  
Near Surface ◽  
Processing Pipeline ◽  
Mode Decomposition ◽  
Lunar Geology ◽  
The One

Structural analysis of lunar regolith not only provides important information about lunar geology but also provides a reference for future lunar sample return missions. The Lunar Penetrating Radar (LPR) onboard China’s Chang’E-3 (CE-3) provides a unique opportunity for mapping the subsurface structure and the near-surface stratigraphic structure of the regolith. The problem of rock positioning and regolith-basement interface highlighting is meaningful. In this paper, we propose an adaptive rock extraction method based on local similarity constraints to achieve the rock location and quantitative analysis for regolith. Firstly, a processing pipeline is designed to image the LPR CH-2 A and B data. Secondly, we adopt an f-x EMD (empirical mode decomposition)-based dip filter to extract low-wavenumber components in the two data. Then, we calculate the local similarity spectrum between the filtered CH-2 A and B. After a soft threshold function, we pick the local maximums in the spectrum as the location of each rock. Finally, according to the extracted result, on the one hand, the depth of regolith is obtained, and on the other hand, the distribution information of the rocks in regolith, which changes with the path and the depth, is also revealed.

Dielectric properties estimation of the lunar regolith at CE-3 landing site using lunar penetrating radar data

Icarus ◽  
2017 ◽  
Vol 284 ◽  
pp. 424-430 ◽  
Author(s):  
Jianqing Feng ◽  
Yan Su ◽  
Chunyu Ding ◽  
Shuguo Xing ◽  
Shun Dai ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Lunar Regolith ◽  
Landing Site ◽  
Radar Data

Thermal modeling of the lunar regolith at the Chang'E‐4 landing site

2021 ◽  
Author(s):  
Honglei Lin ◽  
Shuai Li ◽  
Yangting Lin ◽  
Yang Liu ◽  
Yong Wei ◽  
...  
Keyword(s):  
Thermal Modeling ◽  
Lunar Regolith ◽  
Landing Site

Waypoint Constrained Multi-Phase Optimal Guidance of Spacecraft for Soft Lunar Landing

2019 ◽  
Vol 07 (02) ◽  
pp. 83-104 ◽  
Author(s):  
Kapil Sachan ◽  
Radhakant Padhi
Keyword(s):  
Selection Procedure ◽  
Landing Site ◽  
Terminal Point ◽  
Computationally Efficient ◽  
Soft Landing ◽  
Hard Constraints ◽  
Optimal Guidance ◽  
Safety Constraints ◽  
Multi Phase ◽  
Time Selection

A waypoint constrained multi-phase nonlinear optimal guidance scheme is presented in this paper for the soft landing of a spacecraft on the Lunar surface by using the recently developed computationally efficient Generalized Model Predictive Static Programming (G-MPSP). The proposed guidance ensures that the spacecraft passes through two waypoints, which is a strong requirement to facilitate proper landing site detection by the on-board camera for mission safety. Constraints that are required at the waypoints as well as at the terminal point include position, velocity, and attitude of the spacecraft. In addition to successfully meeting these hard constraints, the G-MPSP guidance also minimizes the fuel consumption, which is a very good advantage. An optimal final time selection procedure is also presented in this paper to facilitate minimization of fuel requirement to the best extent possible. Extensive simulation studies have been carried out with various perturbations to illustrate the effectiveness of the algorithm. Finally, processor-in-loop simulation has been carried out, which demonstrates the feasibility of on-board implementation of the proposed guidance.

scholarly journals Volcanic history of the Imbrium basin: A close-up view from the lunar rover Yutu

2015 ◽  
Vol 112 (17) ◽  
pp. 5342-5347 ◽  
Author(s):  
Jinhai Zhang ◽  
Wei Yang ◽  
Sen Hu ◽  
Yangting Lin ◽  
Guangyou Fang ◽  
...  
Keyword(s):  
Lunar Regolith ◽  
Landing Site ◽  
Lunar Soil ◽  
Lunar Rover ◽  
Surface Exploration ◽  
Mantle Reservoir ◽  
History Of ◽  
Radar Measurements ◽  
Residual Melt

We report the surface exploration by the lunar rover Yutu that landed on the young lava flow in the northeastern part of the Mare Imbrium, which is the largest basin on the nearside of the Moon and is filled with several basalt units estimated to date from 3.5 to 2.0 Ga. The onboard lunar penetrating radar conducted a 114-m-long profile, which measured a thickness of ∼5 m of the lunar regolith layer and detected three underlying basalt units at depths of 195, 215, and 345 m. The radar measurements suggest underestimation of the global lunar regolith thickness by other methods and reveal a vast volume of the last volcano eruption. The in situ spectral reflectance and elemental analysis of the lunar soil at the landing site suggest that the young basalt could be derived from an ilmenite-rich mantle reservoir and then assimilated by 10–20% of the last residual melt of the lunar magma ocean.

scholarly journals Science operation plan of Phobos and Deimos from the MMX spacecraft

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Tomoki Nakamura ◽  
Hitoshi Ikeda ◽  
Toru Kouyama ◽  
Hiromu Nakagawa ◽  
Hiroki Kusano ◽  
...  
Keyword(s):  
Equatorial Plane ◽  
Three Dimensional ◽  
Landing Site ◽  
Satellite Orbit ◽  
Satellite Orbits ◽  
Polar Regions ◽  
Sample Collection ◽  
Resonant Orbits ◽  
Science Operations ◽  
Moon Exploration

AbstractThe science operations of the spacecraft and remote sensing instruments for the Martian Moon eXploration (MMX) mission are discussed by the mission operation working team. In this paper, we describe the Phobos observations during the first 1.5 years of the spacecraft’s stay around Mars, and the Deimos observations before leaving the Martian system. In the Phobos observation, the spacecraft will be placed in low-altitude quasi-satellite orbits on the equatorial plane of Phobos and will make high-resolution topographic and spectroscopic observations of the Phobos surface from five different altitudes orbits. The spacecraft will also attempt to observe polar regions of Phobos from a three-dimensional quasi-satellite orbit moving out of the equatorial plane of Phobos. From these observations, we will constrain the origin of Phobos and Deimos and select places for landing site candidates for sample collection. For the Deimos observations, the spacecraft will be injected into two resonant orbits and will perform many flybys to observe the surface of Deimos over as large an area as possible. Graphical Abstract

Lunar regolith and substructure at Chang’E-4 landing site in South Pole–Aitken basin

2020 ◽  
Author(s):  
Jinhai Zhang ◽  
Bin Zhou ◽  
Yangting Lin ◽  
Meng-Hua Zhu ◽  
Hanjie Song ◽  
...  
Keyword(s):  
Lunar Regolith ◽  
Landing Site ◽  
South Pole

Lunar regolith and substructure at Chang’E-5 landing site in the northern Oceanus Procellarum

2021 ◽  
Author(s):  
Hanjie Song ◽  
Hui Sun ◽  
Gang Yu ◽  
Yang Liu ◽  
Juan Li ◽  
...  
Keyword(s):  
High Resolution ◽  
Lunar Regolith ◽  
Landing Site ◽  
Radar Data ◽  
Detection Methods ◽  
Force Analysis ◽  
Ridge Detection ◽  
Processing Procedure ◽  
Geological Context

Abstract The Lunar Regolith Penetrating Radar (LRPR) on the Chang’E-5 (CE-5) lander was deployed to investigate structures of the regolith. The migration and ridge detection methods were used to process the radar data, and the results indicate a 4.5 m regolith thickness that contains four units at the landing site, which is characterized by different internal reflections that point to their various compositions, mainly comprise protolith and admixed ejecta from the Harpalus, Copernicus, and Aristarchus. High-resolution processing for the LRPR data indicates a few rocks or slates with depth from ~ 0.2 m to over 1 m in the subsurface at the landing site, which was validated by the force analysis during the drilling of the regolith into ~ 1 m depth. The processing procedure proposed in this study is capable of producing reliable and precise images of the lunar regolith substructure, which provides important geological context on the returned drilling samples.

scholarly journals A Novel Approach for Permittivity Estimation of Lunar Regolith Using the Lunar Penetrating Radar Onboard Chang’E-4 Rover

2021 ◽  
Vol 13 (18) ◽  
pp. 3679
Author(s):  
Ruigang Wang ◽  
Yan Su ◽  
Chunyu Ding ◽  
Shun Dai ◽  
Chendi Liu ◽  
...  
Keyword(s):  
High Frequency ◽  
Relative Permittivity ◽  
Traditional Method ◽  
Lunar Regolith ◽  
Landing Site ◽  
New Approach ◽  
High Frequency Radar ◽  
Novel Approach ◽  
Fitting Method ◽  
Simulation Results

Accurate relative permittivity is essential to the further analysis of lunar regolith. The traditional hyperbola fitting method for the relative permittivity estimation using the lunar penetrating radar generally ignored the effect of the position and geometry of antennas. This paper proposed a new approach considering the antenna mounting height and spacing in more detail. The proposed method is verified by numerical simulations of the regolith models. Hence the relative permittivity of the lunar regolith is calculated using the latest high-frequency radar image obtained by the Yutu-2 rover within the first 24 lunar days. The simulation results show that the relative permittivity is underestimated when derived by the traditional method, especially at the shallow depth. The proposed method has improved the accuracy of the estimated lunar regolith relative permittivity at a depth of 0–3 m, 3–6 m, and 6–10 m by 35%, 14%, and 9%, respectively. The thickness of the lunar regolith at the Chang’E 4 landing site is reappraised to be 11.1 m, which improved by ~8% compared with previous studies.

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