Lunar Soil Samples Research Articles

Optimized design of high-efficiency lunar soil sampling tube structure based on stress–strain law

Understanding the influence of the sampling apparatus on in-situ lunar soil lamination information during the sampling process of the direct push-through lunar weathering layer is of great importance. This paper develops a discrete element model for direct push-through lunar weathering layer sampling using the CUG-1A simulated lunar soil developed by the China University of Geosciences as a simulation object and determines the stress–strain law of the inner wall of a sampling tube. A method for optimizing the inner wall structure of a sampling tube based on the stress–strain law is proposed. The structural disturbance of the marker layer and the lunar soil disturbance rate evaluation function are used to assess the degree of disturbance of the laminar information during the sampling process. The results show that the proposed method can effectively reduce the structural disturbance of the lunar soil in-situ laminar information. In addition, it can also optimize the structural information disturbance of the marker layer. The proposed method can decrease the simulated lunar soil disturbance rate from 0.31 to 0.251 and effectively reduce the penetration force load by 15–20% in the direct push-through sampling process.

Quantitative Inversion of Lunar Surface Chemistry Based on Hyperspectral Feature Bands and Extremely Randomized Trees Algorithm

In situ resource utilization (ISRU) is required for the operation of both medium and long-term exploration missions to provide metallic materials for the construction of lunar base infrastructure and H2O and O2 for life support. The study of the distribution of the lunar surface elements (Fe, Ti, Al, and Si) is the basis for the in situ utilization of mineral resources. With the arrival of the era of big data, the application of big data concepts and technical methods to lunar surface chemistry inversion has become an inevitable trend. This paper is guided by big data theory, and the Apollo 17 region and the area near the Copernicus crater are selected for analysis. The dimensionality of the first-order differential spectral features of lunar soil samples is reduced based on Pearson correlation analysis and the successive projections algorithm (SPA), and the extremely randomized trees (Extra-Trees) algorithm is applied to Chang’E-1 Interference Imaging Spectrometer (IIM) data to establish a prediction model for the lunar surface chemistry and generate FeO, TiO2, Al2O3, and SiO2 distribution maps. The results show that the optimum number of variables for FeO, TiO2, Al2O3, and SiO2 is 17, 5, 8, and 30, respectively. The accuracy of the Extra-Trees model using the best variables was improved over that of the original band model, with determination coefficients (R2) of 0.962, 0.944, 0.964, and 0.860 for FeO, TiO2, Al2O3, and SiO2, and root mean square errors (RMSEs) of 1.028, 0.672, 0.942, and 0.897, respectively. The modeling feature variables and model preference methods in this study can improve the inversion accuracy of chemical abundance to some extent, demonstrating the potential of IIM data in predicting chemical abundance and providing a good data basis for lunar geological evolution studies and ISRU.

Spectral interpretation of late-stage mare basalt mineralogy unveiled by Chang’E-5 samples

The western maria of lunar near-side are widely covered with late-stage mare basalts. Due to the lack of returned samples, the mineralogy of the late-stage basalts was previously speculated as having high abundance of olivine based on remote sensing observation. However, here we show that Chang’E-5 (CE-5) lunar soil samples, the ground truth from past unsampled lunar late-stage mare region, give a different interpretation. Our laboratory spectroscopic and X-ray diffraction (XRD) analyses of the CE-5 soil samples demonstrate that their special spectral signatures are representative of iron-rich high-Ca pyroxene rather than olivine. Considering the spectral and compositional similarities between CE-5 soil samples and lunar late-stage basalts, the mineralogy and petrology of CE-5 samples may be able to be generalized to entire lunar late-stage basalts. Our study would provide a constraint on the thermal evolution of the Moon, especially the young lunar volcanism.

JLU-H: A novel lunar highland regolith simulant for use in large-scale engineering experiments

High-fidelity lunar soil simulants are expensive and limited in quantity, which is difficult to meet the needs of large-scale engineering investigations about drilling, excavation or drop tests of spacecraft. For large-scale engineering experiments, the mechanical properties of simulants are more important because they will affect the accuracy and credibility of results. To satisfy the needs of large-scale engineering experiments, this study presents a new lunar highland soil simulant (JLU-H) which was made entirely of naturally available anorthosite complex without any added materials or minerals. The geotechnical properties of JLU-H, such as chemical composition, particle morphology, particle size distribution, specific gravity, bulk density, maximum and minimum density, and shear strength, were determined through a series of indoor tests, and the results were compared with data from Apollo 16 lunar soil sample parameters and other extant highland simulants. The results show that JLU-H can be used as a mechanical substitute for lunar highland soil, and its mechanical property parameters have good similarity with other highland simulants. Although the simulant is not fully representative of the Apollo 16 regolith samples in terms of chemical composition, it is generally close in terms of mineralogical composition. Moreover, compared with other highland simulants, JLU-H has the advantages of low price and the possibility of mass production.

Impact-driven disproportionation origin of nanophase iron particles in Chang’e-5 lunar soil sample

Impact-driven disproportionation origin of nanophase iron particles in Chang’e-5 lunar soil sample

Preparation Method of Lunar Soil Simulant and Experimental Verification of the Performance of an Impact Penetrator for Lunar Soil Exploration

The exploration and investigation of lunar soil can provide necessary information for human beings to understand the Moon’s geological evolution history and solar activity, and is also of great significance for human beings to search for new energy sources. The impact penetrator can dive to a certain depth below the lunar surface, depending on soil compaction effect, and obtain lunar soil detection data by using the onboard sensors. The penetrator has the advantages of small size, light weight, low power consumption and long-term detection ability. In order to verify the diving performance of the developed impact penetrator, a great deal of lunar soil simulant, with physical and mechanical properties similar to a real lunar soil sample, was prepared, which lay the foundation for experimental research. Experiments on the influences of mass–stiffness parameters and dynamic parameters were conducted to obtain reasonable parameter-matching effects and driving parameters. The penetrating experiments in lunar soil simulant, with different relative compaction parameters, indicated that the penetrator could penetrate the simulated lunar soil with high relative compaction, and the penetration depth could reach to 545 mm after 894 shocks in lunar soil, with a relative compaction of 85%. This study on the impact penetrator can provide a feasible approach for in-situ exploration of lunar soil.

Extraterrestrial photosynthesis by Chang’E-5 lunar soil

<h2>Summary</h2> In light of significant efforts being taken toward manned deep space exploration, it is of high technological importance and scientific interest to develop the lunar life support system for long-term exploration. Lunar <i>in situ</i> resource utilization offers a great opportunity to provide the material basis of life support for lunar habitation and traveling. Based on the analysis of the structure and composition, Chang'E-5 lunar soil sample has the potential for lunar solar energy conversion, i.e., extraterrestrial photosynthetic catalysts. By evaluating the performance of the Chang'E-5 lunar sample as photovoltaic-driven electrocatalyst, photocatalyst, and photothermal catalyst, full water splitting and CO₂ conversion are able to be achieved by solar energy, water, and lunar soil, with a range of target product for lunar life, including O₂, H₂, CH₄, and CH₃OH. Thus, we propose a potentially available extraterrestrial photosynthesis pathway on the moon, which will help us to achieve a "zero-energy consumption" extraterrestrial life support system.

Extraterrestrial artificial photosynthesis

In this issue of <i>Joule</i>, Zou et al. studied the lunar soil sample brought back by Chang'E mission 5 for artificial photosynthesis in different approaches, which opens up new possibilities for <i>in situ</i> resource utilization on the moon.

Quantitative verification of 1:35 diluted fused glass disks with 10 mg sample sizes for the wavelength-dispersive X-ray fluorescence analysis of the whole-rock major elements of precious geological specimens

Herein, an improved wavelength-dispersive X-ray fluorescence (WD-XRF) analytical technique for determining the major elements (including SiO2, TiO2, Al2O3, TFe2O3, MnO, MgO, CaO, Na2O, K2O, and P2O5) in precious geological samples, particularly extraterrestrial basaltic rock samples, was developed. For WD-XRF analysis, undersized (approximately 11 mm in diameter) glass disks were prepared by fusing 10 mg of a powdered sample with 350 mg of lithium borate flux at a sample-to-flux ratio of 1:35. Specialized PtAu crucibles and molds were crafted for glass disk preparation to facilitate automatic fluxer mounting. This procedure enabled the automatic preparation of undersized glass disks, with repeatability between sample batches. Calibration curves were constructed for 30 certified reference materials (CRMs), including felsic, intermediate, mafic, and ultramafic igneous rocks. Regular-sized CRM disks with large sample sizes were prepared at the same sample-to-flux ratio as the test samples to avoid issues caused by CRM heterogeneity. The influence of various factors, including glass disk thickness and homogeneity, releasing agent amount, and interference between lines (Br Lα with Al Kα, Rh Lγ2 and Rh Lγ3 with K Kα, and K Kβ with Ca Kα), on analytical accuracy was investigated. Two homogeneous synthetic reference glass samples (ARM-2 and ARM-3) were pulverized and used to verify the analytical results for small samples using the WD-XRF method, which could eliminate the uncertainty caused by sample homogeneity. Subsequently, three CRMs (JB-1b, JA-3, and JR-1) were used to validate the accuracy and precision of the method. Finally, two lunar meteorite samples (NWA4898 and NWA4734) were assayed by the proposed method, and comparison with inductively coupled plasma optical emission spectroscopy results confirmed the reliability of the method. The proposed small sample protocol, which involves the destructive pretreatment of precious and limited extraterrestrial basaltic samples, has great application potential for precious samples such as lunar soil samples.

Numerical simulation on interaction process between impact penetrator and lunar soil particles for lunar subsurface exploration

Unmanned in-situ exploration is an important technique to study the physical and mechanical parameters of lunar composition and evolution. The impact penetrator is an effective device for in-situ detection of the lunar soil profile at predetermined depth. Because of the lack of real lunar soil samples, it is very difficult to study and evaluate the performance of the impact penetrator. In order to truly reflect the interaction between the impact penetrator and lunar soil particles, a simulation model of the lunar soil body was established by means of discrete-element analysis, and the model parameters were matched and verified by the experimental method. Based on this model, the interaction behaviors between the penetrators with different head configurations and the lunar soil body were simulated. The stress field distribution in the lunar soil body and particle movement patterns during the penetrating process were revealed, which reflects the working principle and performance of the penetrator. The numerical simulation on the interaction process between the impact penetrator and lunar soil particles provides a feasible and effective method for the design and optimization of the penetrator, which will contribute to the development of lunar subsurface in-situ exploration technologies.

In‐Situ Photometric Properties of Lunar Regolith Revealed by Lunar Mineralogical Spectrometer on Board Chang’E‐5 Lander

AbstractThe photometric properties of the uppermost lunar regolith are used in the spectroscopic study. China's Chang’E‐5 (CE‐5) mission successfully landed in the Northern Oceanus Procellarum of the Moon, carrying the scientific payload lunar mineralogical spectrometer (LMS). LMS performed full‐view scanning and obtained the reflectance spectra in various geometric configurations. The photometric properties, including the single‐scattering albedo ω and two parameters of the Henyey‐Greenstein phase function (b, c), were derived. Our modeling results showed weak backward scattering and strong forward scattering properties of the regolith at the CE‐5 landing site. Meanwhile, the asymmetry parameter indicates that CE‐5 regolith has weaker forward scattering than the Apollo lunar soil samples and the regolith at the Chang’E‐4 landing site. The derived Hapke parameters can be used for comparison with that of the returned lunar sample, supporting further studies of lunar spectroscopy, and can be the ground truth of the CE‐5 landing area.

Rapid screening of Zr-containing particles from Chang’e-5 lunar soil samples for isotope geochronology: Technical roadmap for future study

New samples returned by China Chang’e-5 (CE-5) mission offer an opportunity for studying the lunar geologic longevity, space weathering, and regolith evolution. The age determination of the CE-5 samples was among the first scientific questions to be answered. However, the precious samples, most in the micrometer size range, challenge many traditional analyses on large single crystals of zircon developed for massive bulk samples. Here, we developed a non-destructive rapid screening of individual zirconium-containing particle for isotope geochronology based on a Micro X-ray fluorescence analysis (µXRF). The selected particles were verified via scanning electron microscopy (SEM), 3D X-ray microscopy (XRM), and focused ion beam scanning electron microscopy (FIB-SEM) techniques, which showed that zirconium-bearing minerals with several microns were precisely positioned and readily suitable for site-specific isotopic dating by second ion mass spectrometry (SIMS). Such protocol could be also applicable in non-destructively screening other types of particles for different scientific purposes. We therefore proposed a correlative workflow for comprehensively studying the CE-5 lunar samples from single particles on nanometer to atomic scales. Linking various microscopic and spectromicroscopic instruments together, this workflow consists of six steps: (1) single-particle selection with non-destructive µXRF technique, (2) 2D/3D morphological and structural characterization with a correlative submicron 3D XRM and nanoscale resolution FIB-SEM imaging methods, (3) SEM analysis of the surface morphology and chemistry of the selected particle, (4) a series of microscopic and microbeam analyses (e.g., SEM, electron probe microanalysis, and SIMS) on the cross-section of the selected particle to obtain structural, mineralogical, chemical, and isotopic features from the micron to nanometer scale, (5) advanced 2D/3D characterization and site-specific sample preparation of thin foil/tip specimens on a microregion of interest in the selected particle with FIB-SEM technique, and (6) comprehensive analyses on the FIB-milled specimens at nanometer to atomic scale with synchrotron-based scanning transmission X-ray microscopy, analytic transmission electron microscopy, and atom probe tomography. Following this technical roadmap, one can integrate multiple modalities into a uniform frame of multimodal and multiscale correlated datasets to acquire high-throughput information on the limited or precious terrestrial and extraterrestrial samples.

Assessment of shear strength and compressibility characteristics of a newly developed lunar highland soil simulant (LSS-ISAC-1) for Chandrayaan lander and rover missions

The engineering properties (shear strength and compressibility) of lunar soils influence the design of landers, rovers, and their mobility behavior on the lunar surface. Assessing such properties is important for any lunar-based studies, and it is usually being determined by using suitable lunar soil simulants. This paper explains the shear strength parameters, stress-strain relationships, and volume change behavior of the newly developed lunar highland soil simulant (LSS-ISAC-1), apart from particle size distribution, which have a profound influence on the engineering behavior. In addition, to the above, other engineering properties such as critical state of the angle of internal friction, dilatancy angle, Young's modulus, Poisson's ratio, internal erodibility, small-strain shear wave velocity, and shear modulus have also been evaluated and presented. Mohr-Coulomb and friction-dilatancy theories are considered as a base for the analysis with the use of statistical predictive equations. The relative density and confining pressures are used as functions in the predictive equation to assess the behavior of the LSS-ISAC-1. The comparison of properties with the actual lunar highland soil samples of the Apollo 16 mission reveals a reasonable similarity of LSS-ISAC-1 with the lunar highland soils.

Design and implementation of an operation system for lunar surface soil sampling &amp;amp; encapsulation

<p indent=0mm>To ensure the successful completion of the unmanned sampling and encapsulation mission of the Chang’e-5 lunar explorer, it is necessary to operate the complex mechanism and equipment on the spacecraft to complete the lunar soil sampling and encapsulation in the uncertain environment within a limited time. To solve this problem, this paper designed a “near verification-remote control” bilaterally integrated operation system; the state-space model was established, which deduces and analyzes the influence factors of the model state transition, and it proposed the autonomous control design based on states drive. Finally, through special verification tests, the correctness and effectiveness of the operating system design were demonstrated. Under the support of this operation system, the Chang’e-5 explorer completed the first unmanned lunar sampling and encapsulation mission in China.

A novel torque analysis method for drilling deep lunar soil by DEM

In order to solve the torque design problem of deep lunar soil sampling using drilling, a novel torque analysis method was presented based on discrete element model (DEM). This method includes three stages: drilling simulation of the bit and stem segment, resultant torque calculation, and predicted curve fitting. First, special drilling models were designed for a bit and stem separately. A high-density equivalent particle group, boundary vibration control, pre-drilling simulation and constant pressure surface control were designed for the bit and stem drilling modelling at different depths to ensure the rationality of the model. An example of the torque synthesis process was given, and the simulation time was analyzed. Finally, the simulation predicted torque curve was plotted and compared with the experimental curve. The experimental and simulation curves show that as the drilling depth increases, the torque increases approximately linearly first and then flattens out gradually after a depth of 1 m. The consistency between the two results indicated that the proposed method was validated. Using this method, engineers can take short time to analyze the torque and design basic parameters of the drill mechanism. The problem of high experimental cost and long simulation time in torque design is solved.

X-ray spectral analysis development in Novosibirsk city (Electron probe microanalysis and X-ray fluorescence analysis using the synchrotron radiation)

Current article considers the contribution of X-ray physicists from the city of Novosibirsk to the formation and development of the two X-ray spectral analysis directions: electron probe microanalysis and X-ray fluorescence analysis using the synchrotron radiation. The research on geological topics at the Institute of Geology and Geophysics of the Siberian Branch of the USSR Academy of Sciences using the MS-46 electron probe microanalyzer of the French company CAMECA (since 1967) served as the basis for the development of methods for the quantitative X-ray microanalysis of rock-forming minerals as the methods for quantitative determination of the contents of elements with low atomic numbers in the long-wavelength X-ray region were still in their infancy. With the development and the improvement of the method’s technical base (microprobes JXA-5A, JEOL, 1975; Kamebaks Micro, CAMECA, 1981; JXA-8100, JEOL, 2003; JXA-8230, JEOL, 2016; electronic computing), the software for controlling the operation of devices and converting the measured intensities of the analytical lines into the concentration of elements continued to changed and improve. The first results of elemental analysis, obtained using the synchrotron radiation to excite X-ray fluorescence at the VEPP-3 accelerating ring at the Institute of Nuclear Physics of the Siberian Branch of the USSR Academy of Sciences, were published in1977. Inthe following years, at the station of elemental SRXRF, samples of various nature were studied — biological (bio tissues of the heart, liver, lungs, hairs, bones, plants), geological, environmental objects (soils, sediments, aerosols, etc.), archaeological sites as well as new technological materials. The procedures for the determination of chemical elements in low-mass samples (milligrams) in unique samples of lunar soil samples, biopsy material of human myocardial tissues, etc. have been developed. The scanning device at the elemental SRXRF station made it possible to obtain the information for reconstructing the climate change for different periods of time – from 100 to 1000 years. A new non-destructive method of confocal X-ray microscopy for studying micro-objects and visualizing the distribution of chemical elements in extended objects on this station are currently being developed.

Lunar megaregolith mixing by impacts: Evaluation of the non-mare component of mare soils

The source of the non-mare component in the lunar mare soil samples is still an open question. A spatially-resolved numerical model tracing the diffusion of non-mare material was developed by means of the Monte Carlo method to study this issue in more detail. The vertically- and laterally-transported non-mare components are recorded separately to assess their concentration on the surface. We find a general higher efficiency of lateral transport than of vertical transport, but the opposite may occur within small zones of interest. The overall (background) distribution of non-mare component is estimated by averaging out regional variations of material composition caused by local impact mixing. We find that almost all the mare surface is mixed with non-mare material. If most of the mare regions have filled basaltic material about 500 m in thickness since the formation of basins, the average non-mare fraction in the top 5 m is about 0.1. The abundance of the non-mare component decreases with increasing distance from the mare-highland boundary, but the slope of the distance-dependence is shallower within ~100 km of the boundary than further away.By comparing the background composition derived from our model with the geochemical analysis and geological interpretation of the lunar mare soil samples, we infer the most plausible geologic processes that have significantly altered the material composition at the sampling sites: for the Apollo 15 and 17 mare soil samples, the large fraction of non-mare material is likely to have resulted from the downslope slumping or lateral transport of the nearby massifs. The Apollo 12 sampling site that is located interior domains of Oceanus Procellarum has a component of Copernicus ejecta. A mixing of both Copernicus ejecta and excavated local underlying material by high-velocity ejecta has altered the composition at the surface. The non-mare material contained in the Apollo 11 and Luna 24 mare soil samples could have been built up gradually by both long-time lateral and vertical mixing. The mare deposit at the Luna 16 landing site is likely to be relatively thin resulting in the abundant vertically transported non-mare component. Since the history of the lunar volcanic eruptions - deposit thicknesses, flux curves and onset of activity - has not been well constrained, we make simple estimates with the first-order accuracy. In addition, it was found that the vertically transported non-mare abundance in the top surface is influenced by both the cessation time of the major mare fillings and the total amount of mare deposit; the laterally-transported non-mare abundance in the top surface is mainly dependent on the cessation time of the major mare fillings. The peak time of eruption would not change the abundance of both the laterally and vertically transported non-mare component.

Electrophysical Model of the Moon’s Soil

Based on the analysis of the data available in the literature on laboratory measurements of the dielectric characteristics of the lunar soil samples delivered to the Earth during the Luna and Apollo missions, an electrophysical model of the upper soil layer of the Moon has been developed. The model takes into account the temperature conditions in the measurement area, temperature changes and the distribution of soil density in the upper regolith layer. The model is intended for numerical simulation of experiments aimed at studying the properties of the lunar soil using electromagnetic waves.

Problem of Iron Isotope Composition of the Earth and Moon. Data on δ57Fe of Luna 16, Luna 20, and Luna 24 Lunar Soil Samples (Report on the XXII Symposium on the Geochemistry of Stable Isotopes, Moscow, October 29–31, 2019)

The model of the formation of the Earth–Moon system during the compression and fragmentation of a gas–dust cloud (Galimov, 2011; Galimov and Krivtsov, 2012) suggests an unusual mechanism for the formation of the Earth’s core. In particular, the model predicts that iron in the Earth’s core should be enriched in the light isotope, and the Earth’s mantle should be, conversely, enriched in the heavy isotope compared to the primary iron (of chondrites). The alternative (megaimpact) model does not allow for this phenomenon. This problem could be solved by comparing the iron isotope composition of the Earth’s and Moon’s mantles. The best representation of the iron isotope composition of the lunar mantle (δ57Fe) is given by the Fe isotope composition of lunar basalts with very low titanium content (VLT), just as the best representation of the isotope composition of iron in the Earth’s mantle is given by the δ57Fe of the Earth’s mid-oceanic ridge basalts (MORB). VLT basalts are relatively scarce on the lunar surface, unlike high-titanium basalts, which fill lunar lowlands. Their iron isotope composition has not yet been measured. We were the first to analyze the iron isotope composition of very low-titanium lunar basalts (VLT) in material delivered by the Luna 24 space mission. Our data indicate that the δ57Fe of Earth’s mantle is higher than the δ57Fe of the bulk silicate Moon, which means (with a high degree of probability) that the Earth’s core is enriched in the light iron isotope. This, in turn, is in good agreement with the model of formation of the Earth–Moon system by the compression and fragmentation of the gas–dust cloud.

Drilling and Migration Characteristics of Critical Size Lunar Soil Particles

Critical size lunar soil particles refer to particles with a particle size similar to the diameter of the drill bit, which is an important factor affecting lunar soil drilling sampling, and its influence is uncertain. In this paper, the discrete element method is used to simulate the drilling sampling process of the critical size lunar soil particles and the influence of the size, position and shape of the lunar particles with critical diameter on the drilling load is analysed. It is found that the critical size lunar soil particles have special migration trajectories and load characteristics during drilling sampling. The size and shape of lunar soil particles are the key factors affecting the drilling load. This study can support the design of drilling tools for lunar soil exploration and sampling.