As lunar exploration advances, the development of durable and sustainable lunar surface architecture is increasingly critical, with a particular focus on material selection and manufacturing processes. However, current technologies and designs have yet to deliver an optimal solution. This study presented an innovative designs pattern for laser-sintered lunar soil bricks, namely a sintered glass outer layer and a core composed of lunar soil particles. For structural reinforcement purposes, a combined system of columns and slabs was implemented to improve the overall strength characteristics. This approach leverages the low thermal conductivity of lunar regolith particles in conjunction with the thermal stability, radiation resistance, and mechanical strength characteristics of glass. In this case, our simulations of heat conduction demonstrated a marked improvement in the thermal insulation properties of the new lunar soil bricks. The low thermal conductivity of lunar regolith effectively serves as an insulating layer, while the column, plate and glass outer layer, with their higher thermal conductivity, enable rapid thermal response across the entire structure and enhance spatial heat transfer uniformity. We further investigated the influence of structural variations on heat transfer mechanisms, revealing that the thickness of the glass layer exclusively modulates the heat transfer rate without altering its spatial distribution. Additionally, comparative analysis of all designed samples demonstrated that the novel sample displays superior thermal insulation properties, reduces average energy consumption by three quarters, and maintains adequate mechanical strength, alongside the proposal of a suitable assembly and construction methodology. Consequently, we believe that glassy composites exhibit substantial potential for space construction. These findings offer valuable insights and recommendations for material design in lunar surface construction.

The discrete element method (DEM) is one of the most popular methods for simulating lunar soil simulants due to the lack of real lunar soil. To reduce the computational consumption and difficulty because of complex particle models, simplified particle models, in which a single particle consists of two, four, or six elements, are discussed in this paper. Three steps, including random generation, particle replacement, and sedimentation, can generate the proposed simulant. The relationship between the mechanical properties of the simulant and microscopic parameters defined in DEM was analyzed by the orthogonal array testing (OATS) technique. Then, the prediction functions, which can calculate mechanical properties from inputting the microscopic parameters without carrying out the DEM, are also established by a back-propagation artificial neural network (BP-ANN). The widely used physical simulants JSC-1 from the USA and FJS-1 from Japan are simulated in DEM from the prediction function with high accuracy.

The existing lunar exploration activities and associated equipment interactions are limited to the surface environment, where the stress state of the lunar regolith is significantly lower than that in laboratory tests conducted on Earth. To address this, this paper proposes a new framework for discrete modeling of large-scale triaxial tests on lunar regolith under low confining pressure. The framework incorporates particle shapes from the Chang'E-5 mission (CE-5) and flexible boundary conditions. Firstly, the shape characteristics of the lunar regolith particles were adopted in the Discrete Element Method (DEM) model to reproduce the mechanical properties of the lunar regolith as accurately as possible. Then, experiments with varying membrane particle stiffness ratios were conducted to explore the effect of the rubber membrane's properties on the mechanical characteristics of lunar regolith under low effective confining pressure. Topological Data Analysis (TDA) tools from persistent homology were utilized to quantify the dynamic response of particles during the onset and development of strain localization. The results indicate that under low effective confining pressure, selecting appropriate rubber membrane types is crucial for accurately determining the mechanical properties of lunar regolith. (c) 2024 COSPAR. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

The formation of a unique microstructure of minerals on the surface of airless bodies is attributed to space weathering. However, it is difficult to distinguish the contributions of meteorite impacts and solar wind to the modification of lunar soil, resulting in limited research on the space weathering mechanism of airless bodies. The thermochemical reactivity of troilite can be used to distinguish the contributions of impact events and solar wind to the modification of lunar soil and provide evidence for space weathering of lunar soil. We examined the structure of troilite particles in the Chang'e-5 lunar soil and determined whether an impact caused the thermal reaction. Microanalysis showed that troilite underwent substantial mass loss during thermal desulfurization, forming a crystallographically aligned porous structure with iron whiskers, an oxygen-rich layer, and other crystallographic and thermochemical evidence. We used an ab initio deep neural network model and thermodynamic calculations to conduct experiments and determine the anisotropy and crystal growth of troilite. The surface microstructure of troilite was transformed by the thermal reaction in the vacuum on the lunar surface. Similar structures have been found in near-Earth objects (NEOs), indicating that small bodies underwent the same impact-induced thermal events. Thus, thermal reactions in a vacuum are likely ubiquitous in the solar system and critical for space weathering alterations of the soil of airless bodies.

The utilization of lunar in-situ resources is an important way to realize the construction and operation of Moon scientific research base. The effect of alumina-alkali activator on the mechanical properties of solidified lunar soil simulant was studied by using basaltic lunar soil simulant as raw material, adding alumina and alkali activator for solidification treatment. Characterisation of hydration products in the simulated lunar soil using X-ray diffraction (XRD), scanning electron microscopy with energy spectroscopy (SEM-EDS), fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG-DTG) and X-ray photoelectron spectroscopy (XPS). The solidified mechanism of lunar soil simulant under the synergistic effect of aluminaalkali activator was discussed. The results showed that the compressive strength and splitting tensile strength of the solidified lunar soil simulant show an increasing trend, and the highest compressive strength was 17.29 MPa, which was 57% greater than that of the control group. The energy evolution process inside the specimen can be divided into four stages: damage initiation, damage increase, damage mutation and damage acceleration. The incorporation of alumina can promote the geopolymerization reaction between the alkali activator and the lunar soil's mineral composition to generate plenty of (N,C)-A-S-H gels that can fill the pores in the particles, thereby improving the mechanical strength of the solidified lunar soil simulant. Finally, the microscopic reaction mechanism model of alumina-alkali activator synergistic solidified lunar soil simulant was established.

The quest for viable construction materials for lunar bases has directed scientific inquiry towards the lunar in-situ resource utilization (ISRU), notably lunar regolith, to synthesize concrete. This study develops an innovative lunar high strength concrete (LHSC) utilizing lunar highlands simulant (LHS-1) and lunar mare simulant (LMS-1) as both precursors and aggregates within the concrete matrix. Mixtures were cured under the conditions simulating the lunar surface temperatures, enabling an evaluation of properties such as flowability, unit weight, compressive strength, modulus of elasticity, and microstructure patterns. Test results indicated that the LMS-1 mixtures exhibited a better flowability and higher unit weight as compared to LHS-1 counterparts. Moreover, the highest 28-day strength was 106.7 MPa and 98.7 MPa for LHS-1 and LMS-1 derived LHSC, respectively. Microstructure analysis revealed that under the identical simulant additions, LHS-1 mixes exhibited superior structural compactness with denser amorphous gels and fewer microcracks. In addition, it possessed a lower Si/ Al ratio and diffraction peak of calcite, along with a greater Ca/Si ratio and hump intensity of amorphous gel phases. The development of this cement-free LHSC, incorporating up to 80 % large-scale lunar materials in the total binder mass, plays a critical role in advancing ISRU on the Moon, thus boosting the viability and sustainability of future lunar construction and habitation while significantly reducing transportation and fabrication costs.

Leading national space exploration agencies and private enterprises are actively engaged in lunar exploration initiatives to accomplish manned lunar landings and establish permanent lunar bases in the forthcoming years. With limited access to lunar surface materials on Earth, lunar regolith simulants are crucial for lunar exploration research. The Chang'e-5 (CE-5) samples have been characterized by state-of-the-art laboratory equipment, providing a unique opportunity to develop a high-quality lunar regolith simulant. We have prepared a high-fidelity PolyU-1 simulant by pulverizing, desiccating, sieving, and blending natural mineral materials on Earth based on key physical, mineral, and chemical characteristics of CE-5 samples. The results showed that the simulant has a high degree of consistency with the CE-5 samples in terms of the particle morphology, mineral and chemical composition. Direct shear tests were conducted on the simulant, and the measured internal friction angle and cohesion values can serve as references for determining the mechanical properties of CE-5 lunar regolith. The PolyU-1 simulant can contribute to experimental studies involving lunar regolith, including the assessment of interaction between rovers and lunar regolith, as well as the development of in-situ resource utilization (ISRU) technologies. (c) 2024 Published by Elsevier B.V. on behalf of China University of Mining & Technology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Lunar-based equipment undertakes the task of movement and transportation in the construction of unmanned lunar base. In the process of moving, the mechanical legs of the equipment are influenced by the lunar soil with special mechanical properties. In order to avoid these uncertainties caused by the lunar soil and other lunar environmental conditions affecting the safety during the mission, a new robust control method with the form of sectionalized expression is proposed based on the dynamic model of the leg-soil system. Lyapunov second method is introduced to demonstrate that the proposed control method can maintain the stability of the leg-soil system successfully. In order to clarify the contact force in the dynamics model, CAS-1 lunar soil simulant that can accurately simulate real lunar soil is used in the calibration test to obtain the precise mechanical parameters. Simulation and experiment are also carried out to verify the proposed control method and the traditional control methods are introduced to make a comparison. Both the simulation and experiment results show that the proposed control method has a better control effect than traditional methods. The proposed method improves the accuracy by an average of 75.7% and 55.9% compared to the traditional methods and the error is limited to 0.2%. By maintaining the stability and accuracy of the leg-soil system, the stability of the lunar-based equipment is improved when performing construction tasks. This study lays the foundation for the construction of unmanned lunar base in advance.

In the exploration of the moon and outer space, our preliminary mission lies in the construction of lunar base. To make lunar concrete with local materials on the moon becomes the key technology to promote the construction of lunar bases. In order to further study the feasibility of using lunar in-situ resources to prepare concrete and build a lunar base, the environment and resources on the lunar surface are analyzed, and the severe challenges brought by extreme environment to concrete preparation and the prerequisites of in-situ resources are clarified. In this paper, the research progress of lunar concrete is summarized from the aspects of raw material acquisition, concrete preparation methods and performance, and the comparative analysis of cement concrete, sulfur concrete, geopolymer concrete and polymer concrete is carried out. Existing studies have shown that in the acquisition of raw materials, sulfur concrete has more advantages, cement concrete and geopolymer concrete are also feasible, but polymer, as a scarce resource on the moon, is difficult to obtain. In terms of preparation methods, cement concrete and geopolymer concrete are more suitable for the production of prefabricated components in artificial environment due to the limitation of external environment and the demand of water circulation, while the in-situ preparation methods represented by sulfur concrete and polymer concrete can be used for the connection and node reinforcement of prefabricated components on the moon. In terms of performance, the mechanical properties of the four kinds of concrete all meet the basic requirements, but the service performance in the harsh environment of the moon needs to be further studied. Meanwhile, the key location characteristics for lunar base construction in different regions are analyzed in terms of topography, environment and in-situ resources. Finally, the future exploration direction of the construction of the lunar bases is proposed.

In this paper, a series of true triaxial tests with different intermediate principal stress ratios are conducted on both the lunar soil simulant and the sandy soils on earth using the discrete element method. An advanced discrete element servomechanism based on polyhedral specimen configuration is implemented such that true triaxial loading paths can be implemented under low confining pressure without introducing severe stress concentration. The high frictional angle and apparent cohesion of the lunar simulant are captured by employing a highly efficient contact model that fuses rolling resistance and van der Waals forces. The employed micro-scale parameters are calibrated based on the triaxial test results of the CSU-LRS-1 lunar soil simulant. The simulation results show that the lunar soil simulant exhibits lower shear strength with an increasing intermediate principal stress ratio. Generally, although the lunar soil simulant has a greater void ratio than that of sandy soils, the former exhibits significantly stronger shear-induced dilatancy and higher shear strength. The evolution of the load-bearing structure is quantified through a contact-normal-based fabric tensor. The interplay between internal structure evolution and external loadings can well explain the difference in mechanical behavior between lunar soil simulant and sandy soils on earth.