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Dust mitigation is one of the most crucial aspects of extraterrestrial exploration. This paper presents a series of experiments on the electrodynamic dust shield (EDS) and how UV radiation affects its efficiency on selected lunar simulants (LHS-1 and LMS-1) across a range of particle sizes, quantities, and surface materials. In this experimental study, VUV is used with a 1500 V AC electric field to mobilise the dust particles resting on either glass, Kapton, or Beta cloth inside a vacuum chamber at ∼ 10 - 6 mbar. The dust removal efficiency is characterised by two quantifying methods: weighing and solar array light transmission. The experimental results show that EDS activation under continuous UV exposure on the simulant particles improves the dust removal rate by 40 to 80 percentage points across all surfaces, with the exception of certain particle size ranges on Beta cloth. The primary force facilitating particle mobilisation was identified as the repulsive electrostatic force, enhanced by ionising mechanisms such as photoemission. [ABSTRACT FROM AUTHOR]

• An improved model for thermal extraction of water resource from icy lunar regolith is introduced. • The importance of thermal transpiration is clarified by numerical analysis. • Water migration process during thermal extraction is visually depicted. • Energy Efficiency Ratio (EER) is introduced to evaluate the parametric effect. The confirmation of water ice's existence in the permanent shadow area led to extensive research in the field of water ice mining from icy lunar regolith. A priori numerical simulation of water ice mining is necessary for guiding the development of lunar water ice mining schemes more reasonably. A 2D axisymmetric numerical simulation model capable of simulating the thermal extraction process about mining water ice from icy lunar regolith is constructed, which is executed in the COMSOL Multiphysics. The thermal extraction cases of lunar regolith with different initial water ice content and heating fluxes are simulated. The EER (energy efficiency ratio) is used to evaluate the efficiency of thermal extraction. The results show that the EER is higher as the initial water ice content is increased, which means more power is used to heat water and less power is used to heat the regolith. The icy lunar regolith with initial water ice content higher than 5.0 wt% is found to be more valuable, over which the EER at the end of thermal extraction will not increase much as the initial water ice content increases. However, the higher heating flux leads to the lower EER at the end of thermal extraction. The speed and economics of thermal extraction are suggested to be weighted before the mission's implementation. The status of thermal diffusion (thermal transpiration) is studied, and the results indicate that thermal diffusion and advection both can be ignored in thermal extraction modeling, unless the average magnitude of temperature gradient and pressure gradient exceed the maximum of 75764 K/m and 11053 Pa/m in our calculation cases, respectively. [ABSTRACT FROM AUTHOR]

The degassing of basic silicate minerals (olivines, pyroxenes, plagioclases) that make up mantle rocks similar in chemical composition to lunar mare basalts has been studied. A setup specially designed for these tasks was used, previously used in the study of chondrite degassing. The results of experimental studies on stepwise heating (without accumulation) with determination of the composition of released gases using gas chromatography methods in the temperature range from 200 to 1000°C are presented. The composition of the released gases was compared with the fugacity of oxygen in olivines. Raman and IR spectra of both the original minerals and minerals after isothermal annealing at various temperatures were obtained. Based on them, the course of thermal transformation of the crystalline structure of minerals was traced and estimates of their stability were obtained. The composition of silicate minerals was compared with samples of lunar soil delivered by the Chinese space mission Chang'e-5. [ABSTRACT FROM AUTHOR]

A laboratory study was performed using the Visible Oxford Space Environment Goniometer in which the broadband (350–1250 nm) bidirectional reflectance distribution functions (BRDFs) of two representative Apollo regolith samples were measured, for two surface roughness profiles, across a range of viewing angles—reflectance: 0–70°, in steps of 5°; incidence: 15°, 30°, 45°, and 60°; and azimuthal: 0°, 45°, 90°, 135°, and 180°. The BRDF datasets were fitted using the Hapke BRDF model to (1) provide a method of comparison to other photometric studies of the lunar regolith and (2) to produce Hapke parameter values which can be used to extrapolate the BRDF to all angles. Importantly, the surface profiles of the samples were characterized using an Alicona 3D® instrument, allowing two of the free parameters within the Hapke model, φ and θ¯, which represent porosity and surface roughness, respectively, to be constrained. The study determined that, for θ¯, the 500–1000 μm size‐scale is the most relevant for the BRDF. Thus, it deduced the following "best fit" Hapke parameters for each of the samples: Apollo 11 rough—w = 0.315 ± 0.021, b = 0.261 ± 0.007, and hS = 0.039 ± 0.005 (with θ¯ = 21.28° and φ = 0.41 ± 0.02); Apollo 11 smooth—w = 0.281 ± 0.028, b = 0.238 ± 0.008, and hS = 0.032 ± 0.006 (with θ¯ = 13.80° and φ = 0.60 ± 0.02); Apollo 16 rough—w = 0.485 ± 0.155, b = 0.155 ± 0.083, and hS = 0.135 ± 0.007 (with θ¯ = 21.69° and φ = 0.55 ± 0.02); Apollo 16 smooth—w = 0.388 ± 0.057, b = 0.063 ± 0.033, and hS = 0.221 ± 0.011 (with θ¯ = 14.27° and φ = 0.40 ± 0.02). Finally, updated hemispheric albedo functions were determined for the samples, which can be used to set laboratory measured visible scattering functions within thermal models. [ABSTRACT FROM AUTHOR]

The Apollo 16 regolith breccia sample suite provides a record of lunar regolith formation from the basin‐forming epoch (~3.9 Ga) through to a time of declining impactor flux (~2 Ga). These rocks have been characterized into three groups: the "ancient," "young," and "soil‐like" regolith breccias on the basis of their petrographic characteristics, and, in the case of the "ancient" and "young" regolith breccias, noble gas inventory. This study investigates the as‐yet unexamined noble gas records of the "soil‐like" regolith breccias to understand more recent regolith evolution processes that occurred at the Apollo 16 landing site. The range of gas concentrations measured for each noble gas in these samples is comparable to those previously reported for the local Apollo 16 soils. The "soil‐like" regolith breccias were found to be more gas rich than the gas poor "young" and "ancient" regolith breccias, consistent with them having formed from comparatively mature soil(s). Our results further confirm the scientific value of lunar regolith breccias and bulk regolith samples as probes of the impact history and the space environment of the lunar surface across a wide range of time. [ABSTRACT FROM AUTHOR]

We investigate the terahertz (THz) scattering and emission properties of lunar regolith by modeling it as a random medium with rough top and bottom boundaries and a host medium situated beneath. The total scattering and emission arise from three sources: the rough boundaries, the volume, and the interactions between the boundaries and the volume. To account for these sources, we model their respective phase matrices and apply the matrix doubling approach to couple these phase matrices to compute the total emission. The model is then used to explore insights into lunar regolith scattering and emission processes. The simulations reveal that surface roughness is the primary contributor to total scattering, while dielectric contrasts between the volume and the boundaries dominate total emission. The THz emissivity is highly sensitive to the regolith dielectric constant, particularly its imaginary part, making it a promising alternative for identifying previously undetected water ice in the lunar polar regions. The THz emissivity model developed in this study can be readily applied to invert the surface parameters of lunar regolith using THz observations. [ABSTRACT FROM AUTHOR]

The Chang'E-6 (CE-6) mission successfully returned 1935.3 g of lunar soil samples from the Apollo basin within the South Pole–Aitken basin. One of its scientific objectives is to investigate the subsurface structure and regolith thickness at the landing site. Using remote sensing datasets, we estimated the regolith and basalt thicknesses at the landing site by employing the crater morphology method and crater excavation technique. A total of 53 concentric craters and 108 fresh craters with varying excavation depths were identified. Our results indicate that the regolith thickness at the CE-6 landing site ranges from 1.1 to 7.0 m, with an average thickness of 3.5 m. Beneath the regolith, the basalt layer consists of high-Ti basalt overlaying low-Ti basalt, with a total thickness of approximately 64 to 82 m, of which the high-Ti basalt layer accounts for about 22 to 30 m. Based on the local geological history, we proposed a stratigraphy at the CE-6 landing site. These findings provide valuable geological context for interpreting the Lunar Penetrating Radar data and analyzing the returned samples. [ABSTRACT FROM AUTHOR]

Bulk chemical composition analysis is a primary and pivotal analytical task for extraterrestrial geological samples (e.g., lunar soil, asteroids, or meteoroids). However, the analysis of mg-level consumption of extraterrestrial geological samples poses a significant challenge to existing analytical techniques. In this study, a new method was developed for trace element determination in bulk extraterrestrial geological samples prepared as lithium borate glasses, following customized procedures for X-ray fluorescence (XRF) analysis with a 10 mg sample by femtosecond LA-ICP-MS. All thirty-two trace elements in the borate glass samples were evenly distributed with homogeneity indices (H) < Hcrit. For the borate glass samples, Si was more suitable as an internal standard for Co, Ni, Cu, and Zn, whereas Al was better for the others. The femtosecond laser greatly reduces the influence of matrix effects, making calibration with non-matrix-matched external standards (NIST 612 and 614) accurate. Although the mass ratio of the flux and sample was as high as 35 : 1, the analytical results of 32 trace elements in six silicate rock reference materials (covering mafic to felsic rock types) using the developed technique were consistent with the reference values within 10% for most elements, and analytical precision (RSD) was also within 10% for most elements. Finally, one lunar basalt (NWA14526) and one shergottite (NWA13190) were assayed using the proposed method, and a comparison with the results of solution nebulization (SN)-ICP-MS confirmed the reliability of the method. The proposed method, combined with XRF, achieved the rapid, simultaneous, and accurate determination of major and trace elements in the same small sample aliquot (10 mg), which is highly suitable for the analysis of extraterrestrial geological samples. [ABSTRACT FROM AUTHOR]

We formulate a method for predicting peak particle forces in a wavefront within a randomly filled 3D granular channel. The wavefronts in our simulation are driven by a sustained impact originating in the bumpy floor of the channel. We show that, when generated in this manner, forces in the driven wavefront within the 3D assembly follow the same power law scaling on material properties and impact velocity as in a 1D chain. A simple scaling of the 1D forces matches results from simulated impact tests we conduct using Soft Sphere Discrete Element method simulations. We then quantify the magnitude of impulse-induced dilation that occurs as a result of varied material properties and gravitational environments, giving an equation that can be used to predict the lofting depth (depth to which particles experience bulk density changes as a result of a laterally propagating wavefront). As predicted by our equation and confirmed with simulated results, dilation is amplified as particle material properties become closer to lunar regolith grains, supporting the hypothesis that impulse-induced surface dilation is the lunar cold spot formation mechanism. [ABSTRACT FROM AUTHOR]

Existing image analysis algorithms cannot achieve consistency with human visual classification results when classifying particles based on angular levels. To address this issue, this paper proposes an image analysis method based on triangle side ratio to quantify particle angularity, referred to as a TSR method. The proposed method utilizes a primary parameter, Mean Angularity, to assess the mean angularity level, and employs three auxiliary parameters to offer insights into the Sharpest Angularity, the Flat Proportion, and the Number of Angularity. When quantifying the angularity, the method further provides the count of convex angles. Each parameter can reflect different characteristic information of the angularity. When using the mean angularity level to order particles, the TSR method achieves the same results as visual classification, and furthermore introduces a range of values for the main parameter corresponding to the different angularity levels. The TSR method is simpler and more stable, since the particle parameters can be calculated directly without contour smoothing, and consistent results are achieved for different shapes with the same degree of angular sharpness. The results of the study on lunar soil, volcanic rock, mechanism stone, and stream stone, show that the TSR method can objectively and comprehensively analyze and quantify the particle angularity. [ABSTRACT FROM AUTHOR]

Lunar exploration and infrastructure development near the Moon's south pole, and at other future lunar settlements, demand a detailed understanding of the geotechnical properties, structure, composition, and stratigraphy of the near-surface lunar regolith. Long term exploration and development activities will require the use of regolith as a construction material for multiple structures, and as unrefined material for resource extraction during in situ resource utilization (ISRU) activities. Upcoming robotic and human exploration will be concentrated near the lunar south pole, which has a dominantly feldspathic composition typical of the lunar highlands. Past missions to lunar highlands terrain (Apollo 16, Luna 20) provide valuable "ground truth" data regarding the geomechanical properties of highlands regolith that serve as a guide for future exploration at the lunar south pole. Lunar highlands simulant LHS-1 has well-characterized geotechnical properties and is an appropriate analogue for highlands lunar regolith in terrestrial engineering studies. Cone penetrometer testing (CPT) measurements of LHS-1 reveal a strong exponential correlation between the G slope parameter and bulk density, which allows information to be obtained regarding the density profile of simulated regolith columns directly from CPT stress versus penetration curves. We show that LHS-1 can be used to replicate the near-surface regolith stratigraphy at the Apollo 16 highland landing region in Earth-based laboratories. The ultimate CPT penetration resistance measured in the laboratory under terrestrial gravity is not directly comparable to that measured under lunar gravity, and here we derive an average reduction factor of Rf = 0.29 to scale penetration resistance values to those measured in situ on the lunar surface. Geotechnical measurements of other lunar simulants combined with experiments similar to those described herein, tailored to the terrain type of interest, will provide crucial information to guide future regolith excavation, construction, and ISRU activities on the lunar surface. • LHS-1 lunar simulant is an appropriate geotechnical analogue for highlands regolith. • A strong correlation exists between CPT penetration resistance and regolith density. • Apollo 16 highlands regolith stratigraphy can be replicated on Earth using LHS-1. • Earth-based CPT values should be reduced by × 0.29 to adjust for lunar conditions. [ABSTRACT FROM AUTHOR]

Lunar soil simulants play a crucial role in scientific research, payload tests and in-situ resource utilization (ISRU) experiments. However, the currently available lunar soil simulants are either low in TiO 2 content (≤3 wt%) or high in TiO 2 content (≥6.7 wt%), despite orbital observations indicating lunar soils with moderate TiO 2 content being widely distributed on the lunar surface. In December 2020, China's Chang'e−5 (CE-5) mission successfully returned a new mare soil sample characterized by high FeO content (22.5 wt%) and moderate TiO 2 content (5.5 wt%), providing an opportunity to develop moderate-TiO 2 lunar soil simulants. This study presents a newly developed simulant of the CE-5 lunar soil named IGG-01, which closely replicates the major physical and chemical properties of the CE-5 lunar soil. The median particle size of IGG-01 is 68.69 ± 4.44 μm, and its estimated specific surface area is 0.34 m2/g. It contains 17.6 wt% FeO and 4.8 wt% TiO 2. It consists of pyroxene (49.3 wt%), plagioclase (40.9 wt%), ilmenite (6.1 wt%), and olivine (3.7 wt%), with specific gravity and bulk density are 3.33 g/cm³ and 1.86 g/cm³, respectively. The friction angle is 41.8°, and the cohesion is 19.2 kPa. It exhibits strong and weak reflectance absorption features in the 1 and 2 μm band centers. The physical properties of IGG-01 are also comparable to those of Apollo samples and typical lunar mare soil simulants. The unique chemical composition of IGG-01 makes it suitable for various scientific and engineering experiments, including but not limited to the study of dusty plasma migration, water formation via solar wind injection, oxygen preparation via hydrogen reduction, and tests involving the movement of rovers and excavation equipment. • A new lunar mare soil simulant (IGG-01) with a TiO 2 content of 4.8 wt% was produced. • It has median grain size of ∼69 μm, bulk density of ∼1.9 g/cm3, cohesion of ∼19 kPa. • It fills the gap between the low-Ti and high-Ti lunar soil simulants. [ABSTRACT FROM AUTHOR]

The oxide-rich lunar surface regolith can be used to extract the oxygen needed for the future of lunar exploration efforts as a consumable for life-support systems and spacecraft propulsion. Various techniques for the extraction of oxygen have been developed already, with solar vapor-phase pyrolysis shown to be a promising yet understudied approach. In contrast to other techniques, it requires only locally available resources, such as unbeneficiated regolith, sunlight, and vacuum in order to liberate oxygen and oxygen-bearing molecules. This study presents experimental work conducted in a purpose-built solar-vacuum furnace showing the evaporation of sodium and iron from a regolith simulant sample and their deposition on the crucible surface. This is matched by the thermochemical equilibrium modeling done in FactSage, which analyzes the process at varying pressures down to ultra-high vacuum. It highlights the need for precise temperature and pressure control, as well as the impact of regolith composition on oxygen dissociation for an efficient extraction of molecular oxygen. • The thermochemical model of the process shows molecular oxygen yields of up to 14.1%. • Low-Titanium Mare is the most promising composition for oxygen production. • Vapor-phase pyrolysis of regolith was demonstrated in a small solar furnace. [ABSTRACT FROM AUTHOR]

Oxygen produced through in‐situ resource utilization (ISRU) is critical to maintaining a permanent human presence on the lunar surface. Molten regolith electrolysis and carbothermal reduction are two promising ISRU techniques for generating oxygen directly from lunar regolith, which is primarily a mixture of oxide minerals; however, both processes require operating temperatures of 1600°C to melt lunar regolith and dissociate the molten oxides. These conditions limit the use of many oxide refractory materials, such as Al2O3 and MgO, due to rapid degradation resulting from reactions between the refractory materials and molten lunar regolith. Yttria‐stabilized zirconia (YSZ) is shown here to be a promising refractory oxide to provide containment of molten regolith while demonstrating limited reactivity. This work focuses on corrosion studies of YSZ powders and dense YSZ crucibles in contact with molten lunar maria and highlands regolith simulants at 1600°C. The interactions between YSZ and molten regolith were characterized using scanning electron microscopy/energy dispersive spectroscopy, X‐ray diffraction, and electron backscatter diffraction. A FactSage thermochemical model was created for comparison with the experimental results. These combined analyses suggest that lunar maria regolith will degrade the YSZ faster than the lunar highlands regolith due to the lower viscosity of the maria regolith. The feasibility of long‐term molten regolith containment with YSZ is discussed based on the YSZ powder and crucible results. [ABSTRACT FROM AUTHOR]

The morphology of particles formed in different environments contains critical information. Thus, the rapid and effective reconstruction of their three-dimensional (3D) morphology is crucial. This study reconstructs the 3D morphology from two-dimensional (2D) images of particles using artificial intelligence (AI). More than 100,000 particles were sampled from three sources: naturally formed particles (desert sand), manufactured particles (lunar soil simulant), and numerically generated digital particles. A deep learning approach based on a voxel representation of the morphology and multi-dimensional convolutional neural networks was proposed to rapidly upscale and reconstruct particle morphology. The trained model was tested using the three particle types and evaluated using different multi-scale morphological descriptors. The results demonstrated that the statistical properties of the morphological descriptors were consistent for the real 3D particles and those derived from the 2D images and the model. This finding confirms the model's validity and generalizability in upscaling and reconstructing diverse particle samples. This study provides a method for generating 3D numerical representations of geological particles, facilitating in-depth analysis of properties, such as mechanical behavior and transport characteristics, from 2D images. [ABSTRACT FROM AUTHOR]

This study investigates terahertz (THz) wave scattering from a simulated lunar regolith surface, with a focus on the Brewster feature, backscattering, and bistatic scattering within the 325 to 500 GHz range. We employed a generalized power-law spectrum to characterize surface roughness and fabricated Gaussian correlated surfaces from Durable Resin V2 using 3D printing technology. The complex dielectric permittivity of these materials was determined through THz time-domain spectroscopy (THz-TDS). Our experimental setup comprised a vector network analyzer (VNA) equipped with dual waveguide frequency extenders for the WR-2.2 band, transmitter and receiver modules, polarizing components, and a scattering chamber. We systematically analyzed the effects of root-mean-square (RMS) height, correlation length, dielectric constant, frequency, polarization, and observation angle on THz scattering. The findings highlight the significant impact of surface roughness on the Brewster angle shift, backscattering, and bistatic scattering. These insights are crucial for refining theoretical models and developing algorithms to retrieve physical parameters for lunar and other celestial explorations. [ABSTRACT FROM AUTHOR]

[Display omitted] • The construction of unmanned lunar bases requires the work of lunar-based equipment. • This study proposes a robust control algorithm for the stable movement of lunar based equipment. • The proposed robust control strategy performs well in real-time experiment. • The proposed robust control algorithm has advantages over existing control strategies. In lunar exploration, lunar-based equipment assumes the responsibility of mobility and transportation during the construction of unmanned lunar base. Legged robots are an important form of the lunar-based equipment due to their mobility and terrain adaptability. However, the influence of lunar terrain and lunar soil cannot be ignored when it comes to studying the mobile stability of lunar-based equipment. Utilizing the dynamic model of the robotic leg, this study proposes a new robust control algorithm, MBC (Model-Based with Continuous expression) algorithm, for lunar-based equipment's robotic leg, and its effectiveness is established through experimentation and theoretical validation with the Lyapunov second method. In the design and verification, the contact force of lunar soil and the lunar environment with low gravity are considered, indicating the applicability of the proposed MBC method in special lunar scenarios. Compared to the conventional PD (Proportional-Differential) and MPD (Model-Based Proportional-Differential) techniques, MBC robust algorithm ultimately demonstrates superior stability and rapidity with a smaller steady state error. [ABSTRACT FROM AUTHOR]

Drilling is a widely used method for exploring extra-terrestrial bodies and seeking information on astrobiology, material composition, and evolution of the universe. The bit cutter of the drill tool is the main component that is in intense contact with the regolith and is of great importance for guaranteeing the cutting performance during drilling. The tine is a special type of cutter, and currently, there is no theoretical model describing its interaction with a lunar regolith simulant during cutting. To address this gap, semi-tine and full-tine cutting tests were performed at different cutting speeds, cutting depths, regolith densities, and tip angles. The experimental results showed that the regolith failure zone has an elliptical shape in the top view and a logarithmic spiral shape in the side view. Based on the failure pattern, a tine cutting mechanics model was built, and its results were compared with those of the experiments. The model exhibited good prediction accuracy for the cutting force, with a maximum error not exceeding 30.96 % and an average error of 13.81 %. To apply the model to extra-terrestrial drilling, a conical drill bit with multi-row serrated tines was designed. By analyzing the error between the theoretical and experimental values of the rotational torque, the model was further refined to provide a better match with the actual cutting results. The proposed cutting mechanics model describing the tine-regolith interaction mechanism can provide a reference for predicting drilling loads during planetary exploration. [ABSTRACT FROM AUTHOR]

The prospect of establishing extra-terrestrial habitats using in situ resource utilization (ISRU) constitutes a long-term goal of multiple space agencies around the world. In this work, we investigate furnace sintering as a potential route for making building blocks—termed synthetic space bricks—using in situ regolith material. By systematically evaluating sintering parameters using a numerical lattice model, coupled with experimental observations and post-sintering characterization, we propose a process protocol for two lunar simulants (lunar highland simulant (LHS-1) and lunar mare dust simulant (LMS-1)) and one Martian simulant (mars global simulant, MGS-1). The resulting bricks demonstrate compressive strengths of up to 45 MPa under uniaxial loading, depending on the simulant used. These strengths are much greater than those typically mandated for structural applications under reduced gravity. Taking recourse to classical ceramic sintering studies, we infer particle-level sintering mechanisms indirectly by measuring temporal evolution exponents of sample dimensions. For all three simulants, volume diffusion appears to be the primary mechanism for particle coalescence. Our results clearly make a strong case for the use of sintering as a potentially scalable method for consolidating regolith into brick-like structures for construction and load-bearing applications in extra-terrestrial settings. [ABSTRACT FROM AUTHOR]

A brief review of theoretical studies of circumlunar dusty plasma, the important factors in the formation of which are electrostatic processes and impacts of micrometeoroids on the lunar surface, is given. Observation data of dust particles in the vicinity of the Moon, obtained within the "Luna-25" mission, are described for the first time. It is shown that there is at least one reliable observation of a dust particle either of lunar origin or associated with the high-speed Perseid stream. The need to improve the Lunar Dust Monitor device on the "Luna-27" lander is discussed. The improvement is associated with the need to install a rod for placing electrostatic sensors at a sufficient distance from the device, which is desirable to reduce disturbances of the surrounding plasma and the near-surface electrostatic field because of the influence of the lander. [ABSTRACT FROM AUTHOR]

Under the dynamic influence of near-surface plasma, intricate dynamics of lunar dust have been observed during the Surveyors and Apollo missions in the form of Lunar horizontal glow. These dynamics are primarily driven by electrostatic forces generated by the continual bombardment of solar wind and highly energetic UV photons on the lunar surface and dust particles. This paper revisits the phenomenon of dust charging within the lunar photoelectron sheath and subsequent dynamics. The investigation has been carried out using a comprehensive model of the lunar photoelectron sheath characterized by observed solar spectra, latitude-dependent Fermionic photoelectrons, non-Maxwellian solar wind electrons, and cold ions. A test dust particle is introduced into the sheath, and equilibrium charge and static levitation conditions are derived. The result of dynamical evolution suggests the existence of a narrow parametric regime corresponding to the periodic hopping trajectory of the dust particle over the lunar surface. In other cases, the dust particles are found to re-impact the surface after a single ballistic hop. We further identify that the discrete charging of the dust could be crucial in determining the dust dynamics, particularly in the tenuous plasmas. The analysis of the discrete dust charging model reveals significant discrepancies with the continuous dust charging model and suggests a lower likelihood of static dust levitation in the lunar environment. The present study is important for unraveling the fundamental processes governing surface evolution on the Moon and other airless bodies throughout the Solar System. [ABSTRACT FROM AUTHOR]

In the past few years, the remarkable progress of commercially operated spacecrafts, the success with reusable rocket engines, as well as the international competition to explore space, has led to a substantial acceleration of activities in the design and preparation of ambitious future lunar missions. In the search for ice and/or cavities imaging the shallow subsurface structure is of vital importance. Hereby, previous studies have shown that seismic interferometry is a promising method to investigate the subsurface properties from passive lunar data. In this study, we want to evaluate the potential of this method further by examining the required duration of seismic measurements and the influence of scattering on the Green's function retrieval. Therefore, we applied seismic interferometry to both measured Apollo 17 data and synthetic data. Our findings indicate that, under optimal conditions, a few hours of data are sufficient when using the method of time‐scaled phase‐weighted stack (ts‐PWS). However, this strongly depends on the inter‐station distance, the orientation toward the principal noise sources, and the timing of the measurement during the lunar cycle. Additionally, we were able to reproduce the measured data using numerical simulations in 2D. The synthetic results show that scattering effects clearly influence the Green's function extraction, especially for larger station distances. Key Points: Green's functions are retrieved from passive Apollo 17 data and synthetic data using seismic interferometryThe convergences time of the Green's function depends on inter‐station distance, noise source distribution and timing during the lunar cycleStrong scattering in the lunar regolith influences the Green's function retrieval, especially for larger station distances [ABSTRACT FROM AUTHOR]

The article presents the results of an experimental study of the strength properties of samples obtained by laser melting from powder compositions of a lunar regolith simulant based on gabbro-diabase. The powder compositions have been obtained by sieving with a fraction range of 50–100 and 100–140 μm from a simulant with a grain-size distribution similar to that of natural regolith. Their properties have been studied on experimental samples with characteristic dimensions of 7.5 × 5 × 6 mm3: apparent density, hardness, and compressive strength in different melting modes. Dependences of these properties on the energy density were obtained in the range from 12 to 25 J/mm3. The measured Vickers hardness of samples fused from a composition of 50–100 μm had a range of 691–830 HV, and samples from a composition of 100–140 μm had a wider range: 330–830 HV. The maximum values of compressive strength for samples from both compositions reached 17–20 MPa with median values of 12 and 17 MPa for the first and second compositions, respectively. These values are quite consistent with those that could be obtained by the process of in situ resource utilization. [ABSTRACT FROM AUTHOR]

The paper presents the results of laboratory tests of selective laser melting (SLM) of powder compositions of lunar regolith simulants from the terrestrial rocks of gabbro-diabase and labradorite, which have different ranges of fractionality. It is shown that compositions with narrow ranges of fractionality of either 50–100 or 100–140 μm make it possible to produce the samples with rather good properties: relatively low porosity and rather good compliance with the requested geometric shape. Experimental dependences of the porosity of tested samples on the energy density of melting are obtained. For both cases of powder compositions from gabbro-diabase with the narrow fractions, either 50–100 or 100–140 μm, the dependences on the energy are practically the same: with increasing energy density up to 20 J/mm3 and greater, the porosity approaches 30–35%. On the other hand, experimental tests shown that SLM technology for a powder composition with a broad range of fractions, from 0 to 100 μm, does not allow testing samples with acceptable properties to be produced—either with low porosity and with reasonable consistency with the specified geometry. [ABSTRACT FROM AUTHOR]

The lunar rover's wheels produce substantial dust emission during movement, presenting safety concerns for astronauts and potential equipment wear. Replicating the dust emission behavior in the low-gravity environment on Earth is challenging. This study proposes a numerical approach to analyze the dust emission distribution of an elastic wire mesh wheel over lunar terrain. The analysis considers adhesion and electrostatic forces within a Discrete Element Method (DEM) model of lunar dust. Then a Multi-Flexible Body Dynamics (MFBD) model of a flexible wire mesh wheel was developed. A virtual single-wheel soil bin experiment was conducted to examine dust emission features under various motion conditions and on rough terrain. Additionally, alternative structures of dust fender were designed to effectively suppress dust, and the effects of the structural features on dust emission were further explored. This comprehensive study provides a valuable reference for simulation and dust-control technologies related to elastic lunar wheels, offering insights that contribute to the effective management of dust emissions from lunar rover wheels. [ABSTRACT FROM AUTHOR]

The Discrete Element Method (DEM) is an important tool for investigating the geotechnical properties of lunar regolith. The accuracy of DEM simulations largely depends on precise particle modeling and the appropriate selection of mesoscopic parameters. To enhance the reliability and accuracy of the DEM in lunar regolith studies, this paper utilized the high-fidelity IRSM-1 lunar regolith simulant to construct a DEM model with realistic particle shapes and conducted an angle of repose (AoR) simulation test. The optimal DEM parameters were calibrated using a combination of the Plackett–Burman test, steepest ascent test, and Box–Behnken design. The results indicate that the sliding friction coefficient, rolling friction coefficient, and surface energy significantly influence the simulation AoR. By optimizing against the measured AoR using a second-order regression model, the optimal parameter values were determined to be 0.633, 0.401, and 0.2, respectively. Under these optimal parameters, the error between the simulation and experimental AoR was 2.1%. Finally, the calibrated mesoscopic parameters were validated through a lifting cylinder test, showing an error of 6.3% between the simulation and experimental results. The high similarity in the shape of the AoR further confirms the accuracy and reliability of the parameter calibration method. This study provides a valuable reference for future DEM-based research on the mechanical and engineering properties of lunar regolith. [ABSTRACT FROM AUTHOR]

This study investigates a neoteric approach in manufacturing lunar regolith-filled shape memory vitrimer (SMV) composites for extraterrestrial applications. A SMV with robust mechanical properties was combined with locally available lunar regolith to form a composite material. Fourier Transfer Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), Thermogravimetric Analysis (TGA), and X-ray fluorescence (XRF) were used to characterize the resin, the regolith simulant, and the prepared SMV-regolith composites. We explored conventional synthesis as well as 3D printing methods for manufacturing the composite. Glass fabric-reinforced laminated composites were also prepared to evaluate the impact tolerance and damage healing efficiency. Compressive strength, flexural strength, and impact resistance of the composite were tested at both room and elevated temperatures. A compressive strength of 96.0 MPa and 5.4 MPa were recorded for composite with 40 wt% regolith ratio at room and elevated temperatures, respectively. The glass fabric reinforced SMV-regolith laminate exhibited a bending strength of 232.7 MPa, good impact tolerance under low-velocity impact test, and good healing efficiency up to two damage healing cycles. The 3D printed SMV-regolith composite using a liquid crystal display (LCD)-based printer exhibited a good thermomechanical property with a compressive and tensile strength of 139.16 MPa and 13.99 MPa, respectively, and a good shape memory effect. However, the LCD-based printing using vat-photopolymerization limits the size of the printed samples. Nonetheless, this study shows that utilization of regolith to form advanced composite is possible. SMV regolith composite is a promising material for lunar base applications due to its simple manufacturing process, excellent mechanical properties, and low energy consumption. [ABSTRACT FROM AUTHOR]

In this work, a matchbox-sized dust detector with a wide measurement range was developed for the lunar surface applications. The characteristics of the detector response to lunar dust simulant deposition mass, particle size, light incidence angle, and temperature are investigated experimentally. It is found that in current study the short-circuit current of the dust detector decreases with the increase in dust deposition mass overall. However, the pattern of current reduction is closely dependent on the size of the dust particles. Specifically, for the dust particle in the range of 75–100 μm, the short-circuit current of the detector tends to decrease slowly and approximately linearly as the dust deposition mass increases, irrespective of light incidence angle. However, for the particle in the size range of 0–25 μm, the decrease of short-circuit current with dust deposition mass can be well described by an exponential function. In addition, the occlusion coefficients for different particle size distributions at different light incidence angles, ranging from −0.88 to −0.08, are also obtained, which is important for determining the mass range of dust deposited on lunar surface-mounted detector at the corresponding conditions. The present research can provide guidance for lunar dust detection with solar cell-based detector. • A lunar dust detector based on mono-crystalline silicon solar cell was developed. • The effect of lunar dust stimulant deposition on the detector was investigated. • The occlusion coefficient under different conditions was determined. [ABSTRACT FROM AUTHOR]

Bioregenerative life-support systems (BLSSs) will be crucial for extended space missions and extraterrestrial habitats. The black soldier fly, Hermetia illucens , is recognized for its efficient organic waste consumption, making it well-suited for closed environments like spacecraft. Our study assessed H. illucens adaptability to different substrates, including a lunar regolith simulant, pertinent to future lunar colonization. Remarkably resilient, H. illucens prepupal larvae successfully pupated in all tested substrates, but pupation timing varied, with no-substrate larvae pupating later. Pupal stage duration also differed, particularly with lunar regolith simulant and sand treatments resulting in longer durations. Substrate treatments significantly influenced the number of emerged adults, with lunar regolith simulant yielding more adults than the no-substrate treatment. Additionally, sand and wood shavings treatments produced more adults, highlighting H. illucens adaptability to various substrates, including lunar regolith. These findings are crucial for future BLSSs design. Additionally, H. illucens adaptability to lunar regolith provides insights into life's adaptability in space environments, guiding future experiments on celestial bodies. This study provides critical data on how different substrates, including lunar regolith simulants, influence H. illucens development and survival, advancing BLSSs and ecological science in both space and terrestrial contexts. • Insects have recently attracted significant interest in the context of BLSSs. • BSFs efficiently consume organic waste and provide a protein-rich food source. • Lunar regolith could be used as a growth medium for BSF larvae. • BSF larvae pupation and survival in lunar regolith was assessed. • This study provides crucial implications for lunar exploration and colonization. [ABSTRACT FROM AUTHOR]

Compared with Earth, the lunar surface's environment is more complex, which suggests that the nuclear energy Helium–Xenon closed Brayton cycle (NHCBC), supplying electricity to the lunar base, may operate under off-design conditions. A thermodynamic model coupled with the lunar surface environment is established in this paper to analyze the effects of lunar environment exposure, including solar radiation exposure, lunar dust toxicity, and meteorite impact, on a given NHCBC. The results show that the output capacity of a given NHCBC is suppressed during the daytime and enhanced during the nighttime. The lunar dust will improve the system's output capacity at night but will also significantly inhibit the output capacity of the cycle during the daytime, resulting in a fluctuation of 824 % of the system without lunar dust. The output fluctuation of NHCBC is reduced after meteorite impact, while the output capacity of the NHCBC is suppressed, destroyed even worse. The optimization of cycle parameters can alleviate the influence of the lunar environment exposure on NHCBC to a minimal extent. This paper aims to analyze the impact of lunar surface environment exposure on the cycle parameters and output work characteristics of NHCBC and to provide some guidance for the subsequent application of nuclear energy in the lunar base. • A mathematical model of a nuclear energy cycle for a lunar base was established. • Lunar surface environment threats pose economic and safety risks to the energy cycle. • Optimizing a single-cycle parameter is unlikely to enhance energy cycle robustness. • Reducing radiator area to enhance cycle robustness sacrifices thermal efficiency. [ABSTRACT FROM AUTHOR]

Production of rocket propellants from lunar resources has the potential to significantly reduce the cost of space exploration. Recent research efforts in this area were focused on the extraction of water from icy regolith for conversion into hydrogen and oxygen, a highly efficient rocket bipropellant. However, water is available only in polar regions of the Moon, and its extraction is a challenge. The present paper aims to assess the feasibility of using propellant components that can be obtained from lunar regolith, specifically oxygen, metal alloys, and sulfur. Thermodynamic performance characteristics of rocket engines using these components were calculated over wide ranges of oxidizer-to-fuel mass ratios. It has been shown that the fuel obtained by extraction of oxygen from regolith, i.e., primarily a mixture of metal alloys, exhibits a relatively high specific impulse of up to 250 s. The use of fuel-lean propellants significantly decreases the temperatures, which facilitates cooling and potentially reduces the deposition of condensed products in the engine; at the same time, the expected decrease in the specific impulse is less pronounced. The use of sulfur in rocket engines is less promising from a thermodynamic point of view, but it enables engine designs without a need for feeding metal alloy powders. Among different designs of sulfur-based engines, a hybrid rocket (fuel: metal alloys mixed with sulfur, oxidizer: liquid oxygen) appears to be the most promising. • Rocket propellants can be directly sourced from lunar regolith. • Such regolith-derived fuels can produce a peak specific impulse of up to 250 s. • Sulfur can be used as either an oxidizer or additive to the regolith- derived fuel. • Different configurations for rocket engines using these fuels are presented. [ABSTRACT FROM AUTHOR]

Angle of repose is an important characteristic of lunar regolith, as it determines the slope stability of features such as hills and craters on the lunar surface and is useful for designing infrastructure and regolith conveyance and handling equipment. Using mineralogically accurate lunar regolith simulants LHS-1 and LHS-1D from Space Resource Technologies (SRT), the recent spin-off of the UCF Exolith Lab®, the relationship between angle of repose and aspects of the simulant, such as sample mass and particle size distribution, are explored. This study provides insight into what affects the angle of repose of lunar regolith, as well as how aspects of the regolith can be manipulated for in situ resource utilization and lunar construction applications. Through the manipulation of lunar regolith simulant particle size gradation and median particle diameter, it is possible to determine which aspects of particle size distribution most impact lunar regolith angle of repose. The results of this study indicate that while many characteristics of a regolith sample influence its angle of repose, the percentage of fines within a sample have the largest effect. [ABSTRACT FROM AUTHOR]

This study reviews major sensing technologies for the Lunar environment and its resources, as they have been developed since the times of Apollo missions. Selected technologies of sensors and instruments for the chemical, isotopic, and structural analysis of Lunar rocks and regoliths, as well as of the Lunar exosphere environment, are presented in a critical review towards an optimised and information-rich framework. Special focus is given on the activated Lunar regolith, and especially the Lunar dust, describing the development of Lunar simulants as the only accessible materials for experimentation and testing of the above technologies. New technologies are also highlighted, such as the development of the OxR microfluidic and spectroscopy integrated device, which, in its small scale aims to detect reactive oxygen species in the Lunar regolith, while in its larger format it is used to release oxygen gas from the Lunar dust and regolith, enabling astronaut respiration and fuel production on the Moon. It is finally suggested that miniaturisation of instruments and sensors, together with the standardisation of output information and characterisation protocols through holistic informational frameworks, will enhance the dynamic expansion and further integration and interoperation of sensors and devices, aiming to an efficient, safer, and resilient utilisation on the Moon and the establishment of sustainable settlements in the near future. [ABSTRACT FROM AUTHOR]

Lunar regolith consists of unconsolidated grains with high porosity, called the fairy castle structure. It is closely linked to the lunar opposition effect, which is the effect where brightness sharply increases as the phase angle approaches 0° ${}^{\circ}$. However, owing to the Earth's gravity, it is difficult to reproduce the structure to study the physical characteristics of the lunar fairy castle structure in the laboratory. We designed a lunar fairy castle structure model for 3D printing. These models had high porosity and were simplified to tree‐like shapes. Various porous conditions of the surface were considered, represented by the number of trees, maximum trunk length, and maximum branch angle. In this study, a laboratory experiment was conducted to measure the reflectance of simulants with a fairy castle structure within a small phase angle range from 1.4° ${}^{\circ}$ to 5.0° ${}^{\circ}$. The result is analyzed for the sample porosity with the tangential slope of the reflectance S(α) $(\alpha)$, which denotes the strength of the opposition effect. In addition, the results of this study were compared with lunar observation data. The porous samples exhibited a relatively large S(α) $(\alpha)$ value. The influence of branch length and attachment angle was very weak in this study. Samples with a porosity between 0.78 and 0.82 represent the similar S(α) $(\alpha)$ values to the lunar observation data, a mean porosity of lunar regolith. In conclusion, our findings suggest a potential correlation between porosity and the opposition effect in printed samples, proposing a new research approach for understanding the lunar opposition effect. Plain Language Summary: The lunar regolith is characterized by loosely bounded grains with high porosity under weak gravity with little compaction. This micro‐structure appears tower‐like and has been referred to as having a "fairy castle structure." The fairy castle structure contributes to multiple scattering of incident light. The brightness of light reflected from the Moon shows a sharp surge when the angle between the Sun, Moon, and a detector approaches zero. This phenomenon, known as the lunar opposition effect, occurs differently depending on the microstructure of a regolith. The lunar opposition effect is now well understood. Because the fairy castle structure is difficult to reproduce in the laboratory, a solution to address this limitation was identified using a 3D printing technique. To understand the opposition effect on the fairy castle structure, various lunar fairy castle simulants were designed and an experimental study was conducted using a goniometer. We analyzed the strength of the opposition effect for varying porosities of samples. The findings reveal a correlation between higher porosity and a stronger opposition effect on the uncompacted lunar fairy castle structures. Key Points: The fairy castle structure of the upper regolith plays an important role in the opposition effect on the lunar surfaceWe made lunar surface simulants resembling the fairy castle structure by using a 3D printerThe simulants with highly porous structures show a strong opposition effect [ABSTRACT FROM AUTHOR]

By placing Apollo 17 regolith samples in a freezer, and storing an equivalent set at room temperature, NASA effectively performed a 50‐year experiment in the kinetics of natural thermoluminescence (TL) of the lunar regolith. We have performed a detailed analysis of the TL characteristics of four regolith samples: a sunlit sample near the landing site (70180), a sample 3 m deep near the landing site (70001), a sample partially shaded by a boulder (72320), and a sample completely shaded by a boulder (76240). We find evidence for a total of eight discrete TL peaks, five apparent in curves for samples in the natural state and seven in samples irradiated in the laboratory at room temperature. For each peak, we suggest values for peak temperatures and the kinetic parameters E (activation energy, i.e. "trap depth," eV) and s (Arrhenius factor, s−1). The lowest natural TL peak in the continuously shaded sample 76240 dropped in intensity by 60 ± 10% (1976 vs. present room temperature samples) and 43 ± 8% (freezer vs. room temperature samples) over the 50‐year storage period, while sunlit and partially shaded samples (70001, 70180, 72321, 72320) showed no change. These results are consistent with the E and s parameters we determined. The large number of peaks, and the appearance of additional peaks after irradiation at room temperature, and literature data, suggest that glow curve peaks are present in lunar regolith at ∼100 K and their intensity can be used to determine temperature and storage time. Thus, a TL instrument on the Moon could be used to prospect for micro‐cold traps capable of the storage of water and other volatiles. Plain Language Summary: Rocky soils, such as the regolith from the Apollo 17 landing site, glow when heated in the dark. This glow, known as thermoluminescence (TL), is caused by previous exposure to radiation, but it can fade depending on ambient temperatures. We therefore have a method for studying the radiation and thermal history of these rocks, but we need to learn the precise details of this process. Nearly 50 years ago, NASA placed some Apollo 17 regolith (a) in a metal cabinet at room temperature and (b) in a freezer. We found that freezer samples did not lose any TL, but the cabinet samples showed considerable fading relative to the freezer samples and relative to samples measured nearly 50 years ago. Combined with a detailed computer analysis of the data, these results enable us to understand the relationships between TL, time, and environmental conditions. Most importantly, this method will enable us to search for tiny locations in the polar regions of the Moon, called cold traps, where water and other volatiles may have accumulated. This information is important for understanding the history of the Moon, and it will support exploration efforts which need water and volatiles. Key Points: The thermoluminescence (TL) of Apollo 17 regolith samples has been studied. The kinetic parameters of 8 peaks present were determinedEquilibrium temperatures have been determined for four location types (2 massif, 2 valley), which agree well with independent thermometersThese results suggest that a TL instrument (hand held or robotic) could be used to locate micro‐cold traps (and volatiles) on the Moon [ABSTRACT FROM AUTHOR]

Direct Contact Membrane Distillation (DCMD) uses low heat sources to separate water from urea, which was then used as a plasticizer in regolith-based cement to make it more workable. The work investigated separating potable water and urea from artificial urine using DCMD and then characterizing the products. Water was successfully separated from the artificial urine solution as characterized by density, conductivity, pH, and substance concentrations. The concentrated urine solution was used in regolith-based cement cured under vacuum at temperatures that simulated temperatures that would be expected in construction on the Moon. Workability and other properties were improved by replacing water with concentrated urine solution in the mix. [ABSTRACT FROM AUTHOR]

Magnetite is rare on the Moon. The ubiquitous presence of magnetite in lunar soil has been hypothesized in previous Apollo Mössbauer spectroscopy and electron spin resonance studies, but there is currently no mineralogical evidence to prove it. Here, we report a large number of submicroscopic magnetite particles embedded within iron-sulfide on the surface of Chang'e-5 glass, with a close positive correlation between magnetite content and the TiO2 content of the surrounding glass. The morphology and mineralogy of the iron-sulfide grains suggest that these magnetite particles formed via an impact process between iron-sulfide droplets and silicate glass melt, and ilmenite is necessary for magnetite formation. Magnetite in lunar glass is a potential candidate for the "magnetite-like" phase detected in the Apollo era and suggests that impact-induced submicroscopic magnetite may be ubiquitous in high-Ti regions of the Moon. Moreover, these impact-induced magnetite particles may be crucial for understanding the lunar magnetic anomalies and mineral components of the deep Moon. [ABSTRACT FROM AUTHOR]

Lunar exploration is of significant importance in the development and utilization of in situ lunar resources, water ice exploration, and astronomical science. In recent years, ground-based radar (GBR) has gained increasing attention in the field of lunar exploration due to its flexibility, low cost, and penetrating capabilities. This paper reviews the scientific research on lunar exploration using GBR, outlining the basic principles of GBR and the progress made in lunar exploration studies. Our paper introduces the fundamental principles of lunar imaging using GBR and systematically reviews studies on lunar surface/subsurface detection, the dielectric properties inversion of the lunar regolith, and polar water ice detection using GBR. In particular, the paper summarizes the current development status of the Chinese GBR and forecasts future development trends in China. This review will enhance the understanding of lunar exploration results using GBR radar, systematically demonstrate the main applications and scientific achievements of GBR in lunar exploration, and provide a reference for GBR radar in future lunar exploration missions. [ABSTRACT FROM AUTHOR]

Lunar regolith is the most abundant resource on the lunar surface, which can be used for in-situ fabrication and repair technologies. Vat photopolymerization-based additive manufacturing is among the most promising techniques, capable of producing precise ceramic parts of complex shapes from the lunar regolith feedstock for the needs of future crewed exploration missions to the Moon. One of the under-studied aspects of additive manufacturing with lunar regolith is the pre-and post-treatment procedures, which would ensure optimal energy and material consumption and the best printing performance. The goal of the present article was to define the influence of the mineral composition of lunar regolith simulants and the parameters of their pre-processing on the properties of sintered regolith ceramics. It was found that the highland regolith could be sintered to higher relative density compared to the mare regolith. The optimal sintering temperature was determined to be 1150 °C for both types of lunar regolith. An optimal mineral and fractional composition for the regolith feedstock was determined based on the trade-off analysis between lunar regolith sinterability and its printability via vat photopolymerization-based additive manufacturing. Vat-polymerization was performed to produce complex-shaped ceramic parts, yielding 95 % of relative density and a mean ultimate flexural strength of 106 ± 5 MPa, confirming the proposed trade-off point. [ABSTRACT FROM AUTHOR]

Crewed missions to the Moon may resume as early as 2026 with NASA's Artemis III mission, and lunar dust exposure/inhalation is a potentially serious health hazard that requires detailed study. Current dust exposure limits are based on Apollo‐era samples that spent decades in long‐term storage on Earth; their diminished reactivity may lead to underestimation of potential harm that could be caused by lunar dust exposure. In particular, lunar dust contains nanophase metallic iron grains, produced by "space weathering"; the reactivity of this unique component of lunar dust is not well understood. Herein, we employ a chemical reduction technique that exposes lunar simulants to heat and hydrogen gas to produce metallic iron particles on grain surfaces. We assess the capacity of these reduced lunar simulants to generate hydroxyl radical (OH*) when immersed in deionized (DI) water, simulated lung fluid (SLF), and artificial lysosomal fluid (ALF). Lunar simulant reduction produces surface‐adhered metallic iron "blebs" that resemble nanophase metallic iron particles found in lunar dust grains. Reduced samples generate ~5–100× greater concentrations of the oxidative OH* in DI water versus non‐reduced simulants, which we attribute to metallic iron. SLF and ALF appear to reduce measured OH*. The increase in observed OH* generation for reduced simulants implies high oxidative damage upon exposure to lunar dust. Low levels of OH* measured in SLF and ALF imply potential damage to proteins or quenching of OH* generation, respectively. Reduction of lunar dust simulants provides a quick cost‐effective approach to study dusty materials analogous to authentic lunar dust. [ABSTRACT FROM AUTHOR]

This study aimed to explore the possibility of improving the fertility of lunar soil through the reuse of resources by composting household waste and collecting composting fermentation broth. The fermentation broth was used to culture a simulated lunar soil at different concentration gradients for 30 days under aerobic and anaerobic conditions. Microbial biomass carbon and nitrogen content, typical mineral elements, and the microbial community were tested to determine whether the fertility of the lunar soil had improved. Results showed that the microorganisms in the simulated lunar soil samples successfully adhered and grew under both aerobic and anaerobic experimental conditions. The simulated lunar soil samples cultured in the anaerobic environment outperformed those in the aerobic environment regarding microbial biomass growth and water-soluble mineral elements. The study results create opportunities for the future reuse of domestic garbage on the lunar base, providing a technical basis for the in situ reuse of lunar soil resources for plant cultivation. [ABSTRACT FROM AUTHOR]

For space missions to either the Moon or Mars, protecting mechanical moving parts from the abrasive effects of prevailing surface dust is crucial. This paper compares the abrasive effects of two lunar and two Martian simulant regoliths using special pin-on-disc tests on a stainless steel/polytetrafluoroethylene (PTFE) sealing material pair. Due to the regolith particles entering the contact zone, a three-body abrasion mechanism took place. We found that friction coefficients stabilised between 0.2 and 0.4 for all simulants. Wear curves, surface roughness measurements, and microscopic images all suggest a significantly lower abrasion effect of the Martian regoliths than that of the lunar ones. It applies not only to steel surfaces but also to the PTFE pins. The dominant abrasive micro-mechanism of the disc surface is micro-ploughing in the case of all tests, while the transformation of the counterface is mixed. The surface of pin material is plastically transformed through micro-ploughing, while the material is removed through micro-cutting due to the slide over hard soil particles. [ABSTRACT FROM AUTHOR]

The physical properties of lunar regolith are crucial for exploration planning, hazard assessment, and characterizing scientific targets at global and polar scales. The dielectric constant, a key property, offers insights into lunar material distribution within the regolith and serves as a proxy for identifying volatile-rich regoliths. Miniature radio frequency (Mini-RF) on the Lunar Reconnaissance Orbiter (LRO) provides a potential tool for mapping the lunar regolith's physical nature and assessing the lunar volatile repository. This study presents global and polar S-band Mini-RF dielectric signatures of the Moon, obtained through a novel deep learning inversion model applied to Mini-RF mosaics. We achieved good agreement between training and testing of the model, yielding a coefficient of determination (R2 value) of 0.97 and a mean squared error of 0.27 for the dielectric constant. Significant variability in the dielectric constant is observed globally, with high-Ti mare basalts exhibiting lower values than low-Ti highland materials. However, discernibility between the South Pole–Aitken (SPA) basin and highlands is not evident. Despite similar dielectric constants on average, notable spatial variations exist within the south and north polar regions, influenced by crater ejecta, permanently shadowed regions, and crater floors. These dielectric differences are attributed to extensive mantling of lunar materials, impact cratering processes, and ilmenite content. Using the east- and west-looking polar mosaics, we estimated an uncertainty (standard deviation) of 1.01 in the real part and 0.03 in the imaginary part of the dielectric constant due to look direction. Additionally, modeling highlights radar backscatter sensitivity to incidence angle and dielectric constant at the Mini-RF wavelength. The dielectric constant maps provide a new and unique perspective of lunar terrains that could play an important role in characterizing lunar resources in future targeted human and robotic exploration of the Moon. [ABSTRACT FROM AUTHOR]

In this study, we examine the Russian automatic lunar missions "Luna-25," "Luna-26," and the scientific objectives and landing site of the "Luna-27″ spacecraft. The landing of "Luna-27″ is planned directly in the South Polar region, which, due to ballistic and engineering requirements, is confined to a sector extending from 51°E to 1°W in longitude and from 83°S to 79°S in latitude. This area is characterized by complex terrain, and to identify suitable landing territories, a suitability map has been created that takes into account the distribution of slopes, the degree of illumination, and visibility of Earth. A total of five sites measuring 30 × 15 km (landing ellipse) within the considered region meet such scientific and technical requirements as slope distributions of less than 7–10°, sunlight illumination of more than 35 %, and Earth visibility of more than 50 %. All landing sites are ranked by priority from 1 to 5 depending on the content of water equivalent of hydrogen (WEH) in the lunar soil. Site №1, by its characteristics, is considered the best and may be chosen as the primary landing site, while sites №2 and №3 could serve as backups. It is demonstrated that with increased landing precision, with a deviation probability from the given point up to 0.5 km, the number of suitable landing sites satisfying primarily scientific rather than engineering-technical safety criteria, which are also inherently met, significantly increases. • Landing zone: 51°E to 1°W, 83°S to 79°S. • Map identifying suitable area for spacecraft landing. • Slope distribution, Sun illumination, Earth visibility, water-hydrogen content. • Only five sites (30 × 15 km ellipsoids) meet criteria. • Landing accuracy crucial for meeting scientific needs. [ABSTRACT FROM AUTHOR]

Sustainable structures are an important area of research, particularly for anticipated extended human presence on the Moon or Mars. Persistent human presence on the Moon will require building materials that are already present at the site to construct bases. The high cost associated with reinforcing metal (rebar) in mission payloads necessitates the exploration of alternative reinforcement methods for sustained lunar bases. Human hair is strong in tensile strength and will become available in any long-term mission. By using otherwise wasted hair instead of heavy metal, mission payloads and costs could be lowered. Concrete workability, compressive strength, and porosity were measured for a series of different cement compositions. These compositions consisted of combinations of Ordinary Portland Cement (OPC), lunar regolith, deionized (DI) water and human hair. Increased workability and porosity were found for increasing hair concentrations. Compressive strength slightly decreased with increased hair concentration. [ABSTRACT FROM AUTHOR]

This article explores the influence of lunar regolith and rover structure, such as mast design and material composition, on antenna parameters. It focuses on the distinctive difficulties of communication in the lunar environment, which need specialized antenna solutions. This study specifically examines the performance of antennas on the lunar Rashid rover within the Atlas crater, a landing site on the moon, considering two antenna types: a sleeve dipole antenna and an all-metal patch antenna. Thermal analyses reveal temperatures in the Atlas crater can exceed 80 °C during lunar mid-day. The findings highlight the effect of different materials used as thermal coatings for Rashid rover antennas, as well as the influence of rover materials on antenna performance. Furthermore, this study extends to analyze the conductivity and depth of lunar regolith within the Atlas crater. Given the critical role of antennas in wireless communication, understanding how lunar regolith properties affect antenna performance is essential. This research contributes to the creation of a strong communication system for the Rashid rover and future lunar missions by considering the features of the lunar regolith in addition to the rover's size and material attributes. [ABSTRACT FROM AUTHOR]

Lunar soil undergoes space weathering and accumulates optically active opaque particles (OAOpq) of different sizes, resulting in a darkening or red shift of the reflectance spectrum. The surfaces of weakly weathered objects exhibit spectral characteristics of strong weathering; these mechanisms are still unclear. The causes of OAOpq in lunar soil are complex, especially for submicrometer particles, which account for the largest mass proportion. We found ubiquitous impact-dispersed Fe–Fe 1- x S core–shell particles in Chang'e-5 lunar soil impact glass and splatter. The crystal structure, particle size distribution, and chemical composition of OAOpq in the impact glass indicate that these OAOpq consist of sulfides or metals from multiple sources. Thermodynamic evidence, diffusion behavior, and particle dispersion characteristics indicate that impact dispersion is the most likely formation mechanism of these OAOpq. The proposed impact dispersion provides a reason for the large number of OAOpq and the limited products for in situ reactions. This process explains why lunar soil with a low degree of weathering exhibits substantial spectral modification properties. The results provide insights into space weathering of the lunar surface and also imply that impact-dispersed OAOpq may be the primary modification type on asteroid surfaces. The unique chemical properties of Fe–Fe 1- x S OAOpq also indicate that the lunar regolith has the potential for resource utilization. [ABSTRACT FROM AUTHOR]