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

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.

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

Remote Sensing ◽

10.3390/rs13010048 ◽

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.

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Parameter Estimation of Lunar Regolith from Lunar Penetrating Radar Data

Sensors ◽

10.3390/s18092907 ◽

2018 ◽

Vol 18 (9) ◽

pp. 2907 ◽

Cited By ~ 8

Author(s):

Ling Zhang ◽

Zhaofa Zeng ◽

Jing Li ◽

Ling Huang ◽

Zhijun Huo ◽

...

Keyword(s):

Dielectric Constant ◽

Parameter Estimation ◽

Lunar Regolith ◽

Relative Dielectric Constant ◽

Landing Site ◽

Radar Data ◽

Titanium Content ◽

Complex Model ◽

Electrical Parameters ◽

Near Surface

Parameter estimation of the lunar regolith not only provides important information about the composition but is also critical to quantifying potential resources for lunar exploration and engineering for human outposts. The Lunar Penetrating Radar (LPR) onboard China’s Chang’E-3 (CE-3) provides a unique opportunity for mapping the near-surface stratigraphic structure and estimating the parameters of the regolith. In this paper, the electrical parameters and the iron-titanium content of regolith are estimated based on the two sets of LPR data. Firstly, it is theoretically verified that the relative dielectric constant can be estimated according to the difference of the reflected time of two receivers from a same target. Secondly, in order to verify the method, a parameter estimation flow is designed. Subsequently, a simple model and a complex model of regolith are carried out for the method verification. Finally, on the basis of the two sets of LPR data, the electrical parameters and the iron-titanium content of regolith are estimated. The relative dielectric constant of regolith at CE-3 landing site is 3.0537 and the content of TiO2 and FeO is 14.0127%. This helps us predict the reserves of resources at the CE-3 landing site and even in the entire Mare Imbrium.

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

Remote Sensing ◽

10.3390/rs12040629 ◽

2020 ◽

Vol 12 (4) ◽

pp. 629 ◽

Cited By ~ 3

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.

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The Cessation of Continuous Turbulence as Precursor of the Very Stable Nocturnal Boundary Layer

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-12-064.1 ◽

2012 ◽

Vol 69 (11) ◽

pp. 3097-3115 ◽

Cited By ~ 58

Author(s):

B. J. H. Van de Wiel ◽

A. F. Moene ◽

H. J. J. Jonker

Keyword(s):

Boundary Layer ◽

Time Scale ◽

Nocturnal Boundary Layer ◽

Surface Heat ◽

Heat Extraction ◽

Local Similarity ◽

Temporary Reduction ◽

Turbulent Friction ◽

Near Surface ◽

Flow Acceleration

Abstract The mechanism behind the collapse of turbulence in the evening as a precursor to the onset of the very stable boundary layer is investigated. To this end a cooled, pressure-driven flow is investigated by means of a local similarity model. Simulations reveal a temporary collapse of turbulence whenever the surface heat extraction, expressed in its nondimensional form h/L, exceeds a critical value. As any temporary reduction of turbulent friction is followed by flow acceleration, the long-term state is unconditionally turbulent. In contrast, the temporary cessation of turbulence, which may actually last for several hours in the nocturnal boundary layer, can be understood from the fact that the time scale for boundary layer diffusion is much smaller than the time scale for flow acceleration. This limits the available momentum that can be used for downward heat transport. In case the surface heat extraction exceeds the so-called maximum sustainable heat flux (MSHF), the near-surface inversion rapidly increases. Finally, turbulent activity is largely suppressed by the intense density stratification that supports the emergence of a different, calmer boundary layer regime.

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Seismic investigations of the Martian near-surface at the InSight landing site

10.5194/egusphere-egu2020-20481 ◽

2020 ◽

Author(s):

Cedric Schmelzbach ◽

Nienke Brinkman ◽

David Sollberger ◽

Sharon Kedar ◽

Matthias Grott ◽

...

Keyword(s):

Deep Structure ◽

Landing Site ◽

P Wave ◽

Mission Design ◽

Normal Operation ◽

Seismic Signals ◽

Martian Surface ◽

Broadband Seismometer ◽

Near Surface ◽

Martian Regolith

The InSight ultra-sensitive broadband seismometer package (SEIS) was installed on the Martian surface with the goal to study the seismicity on Mars and the deep interior of the Planet. A second surface-based instrument, the heat flow and physical properties package HP3, was placed on the Martian ground about 1.1 m away from SEIS. HP3 includes a self-hammering probe called the &#8216;mole&#8217; to measure the heat coming from Mars' interior at shallow depth to reveal the planet's thermal history. While SEIS was designed to study the deep structure of Mars, seismic signals such as the hammering &#8216;noise&#8217; as well as ambient and other instrument-generated vibrations allow us to investigate the shallow subsurface. The resultant near-surface elastic property models provide additional information to interpret the SEIS data and allow extracting unique geotechnical information on the Martian regolith.The seismic signals recorded during HP3 mole operations provide information about the mole attitude and health as well as shed light on the near-surface, despite the fact that the HP3 mole continues to have difficulty penetrating below 40 cm (one mole length). The seismic investigation of the HP3 hammering signals, however, was not originally planned during mission design and hence faced several technical challenges. For example, the anti-aliasing filters of the seismic-data acquisition chain were adapted when recording the mole hammering to allow recovering information above the nominal Nyquist frequency. In addition, the independently operating SEIS, HP3 and lander clocks had to be correlated more frequently than in normal operation to enable high-precision timing.To date, the analysis of the hammering signals allowed us to constrain the bulk P-wave velocity of the volume between the mole tip and SEIS (top 30 cm) to around 120 m/s. This low velocity value is compatible with laboratory tests performed on Martian regolith analogs with a density of around 1500 kg/m3. Furthermore, the SEIS leveling system resonances, seismic recordings of atmospheric pressure signals, HP3 housekeeping data, and imagery provide additional constraints to establish a first seismic model of the shallow (topmost meters) subsurface at the landing site.

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Iris Hanika's Treffen Sich Zwei: Reception, Analysis and Interpretation

10.26686/wgtn.17004778 ◽

2021 ◽

Author(s):

◽

Kerry Alistair Nitz

Keyword(s):

Quantitative Analysis ◽

Qualitative Approach ◽

The Other ◽

The Novel ◽

Quantitative Evidence ◽

Literary Context ◽

Narrative Functions ◽

The One ◽

High Level ◽

The Relationship

Iris Hanika’s commercially and critically successful novel Treffen sich zwei makes use of several techniques in the characterisation of its protagonists. Many of its reviews focus on the author’s deliberate placement of links to a wider literary context. Their interest extends from questions of genre-mixing through to the identification of direct quotes from other authors’ works. The critical preoccupation with intertexts demonstrates their importance for the readers’ response to the novel. More specifically, certain reviews highlight the important role intertexts play in the characterisation of the protagonists. This study catalogues the intertexts, metaphors and parodies in Treffen sich zwei and, by means of quantitative analysis, identifies high-level patterns in the use of these techniques. In particular, patterns are identified between, on the one hand, the different narrative functions of the intertexts and, on the other hand, the different ways in which they are interwoven in the text. The data also shows that distinct patterns are associated with each of the two protagonists and that certain patterns change in the course of the novel in parallel with the changes in the relationship between them. This quantitative evidence is supported by a more detailed, qualitative approach, which examines how specific intertexts or metaphors are used for the purposes of characterisation. In addition, variations in voice are used to distinguish the two main protagonists in a manner consistent with the intertexts and metaphors. It is thanks to the combination of these techniques that the theme of meeting encapsulated in the title, Treffen sich zwei, is woven into the textual fabric of the novel.

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

Icarus ◽

10.1016/j.icarus.2016.12.005 ◽

2017 ◽

Vol 284 ◽

pp. 424-430 ◽

Cited By ~ 23

Author(s):

Jianqing Feng ◽

Yan Su ◽

Chunyu Ding ◽

Shuguo Xing ◽

Shun Dai ◽

...

Keyword(s):

Dielectric Properties ◽

Lunar Regolith ◽

Landing Site ◽

Radar Data

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

Geophysical Research Letters ◽

10.1029/2020gl091687 ◽

2021 ◽

Author(s):

Honglei Lin ◽

Shuai Li ◽

Yangting Lin ◽

Yang Liu ◽

Yong Wei ◽

...

Keyword(s):

Thermal Modeling ◽

Lunar Regolith ◽

Landing Site

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Data Sets

Hurricane Climatology ◽

10.1093/oso/9780199827633.003.0009 ◽

2013 ◽

Author(s):

James B. Elsner ◽

Thomas H. Jagger

Keyword(s):

Model Building ◽

Careful Analysis ◽

Logical Structure ◽

Fortran Program ◽

Data Sets ◽

Data Set ◽

Near Surface ◽

Wind Speeds ◽

The North ◽

The One

Hurricane data originate from careful analysis of past storms by operational meteorologists. The data include estimates of the hurricane position and intensity at 6-hourly intervals. Information related to landfall time, local wind speeds, damages, and deaths, as well as cyclone size, are included. The data are archived by season. Some effort is needed to make the data useful for hurricane climate studies. In this chapter, we describe the data sets used throughout this book. We show you a work flow that includes importing, interpolating, smoothing, and adding attributes. We also show you how to create subsets of the data. Code in this chapter is more complicated and it can take longer to run. You can skip this material on first reading and continue with model building in Chapter 7. You can return here when you have an updated version of the data that includes the most recent years. Most statistical models in this book use the best-track data. Here we describe these data and provide original source material. We also explain how to smooth and interpolate them. Interpolations are needed for regional hurricane analyses. The best-track data set contains the 6-hourly center locations and intensities of all known tropical cyclones across the North Atlantic basin, including the Gulf of Mexico and Caribbean Sea. The data set is called HURDAT for HURricane DATa. It is maintained by the U.S. National Oceanic and Atmospheric Administration (NOAA) at the National Hurricane Center (NHC). Center locations are given in geographic coordinates (in tenths of degrees) and the intensities, representing the one-minute near-surface (∼10 m) wind speeds, are given in knots (1 kt = .5144 m s−1) and the minimum central pressures are given in millibars (1 mb = 1 hPa). The data are provided in 6-hourly intervals starting at 00 UTC (Universal Time Coordinate). The version of HURDAT file used here contains cyclones over the period 1851 through 2010 inclusive. Information on the history and origin of these data is found in Jarvinen et al (1984). The file has a logical structure that makes it easy to read with a FORTRAN program. Each cyclone contains a header record, a series of data records, and a trailer record.

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