Lunar soil, as an in-situ resource, holds significant potential for constructing bases and habitats on the Moon. However, such constructions face challenges including limited mechanical strength and extreme temperature fluctuations ranging from -170 degrees C to +133 degrees C between lunar day and night. In this study, we developed a 3D-printed geopolymer derived from lunar regolith simulant with an optimized zig-zag structure, exhibiting exceptional mechanical performance and thermal stability. The designed structure achieved remarkable damage tolerance, with a compressive strength exceeding 12.6 MPa at similar to 80 vol% porosity and a fracture strain of 3.8 %. Finite element method (FEM) simulations revealed that the triangular frame and wavy interlayers enhanced both stiffness and toughness. Additionally, by incorporating strategically placed holes and extending the thermal diffusion path, we significantly improved the thermal insulation of the structure, achieving an ultralow thermal conductivity of 0.24 W/(m K). Furthermore, an iron-free geopolymer coating reduced overheating under sunlight by 51.5 degrees C, underscoring the material's potential for space applications.

In situ resource utilization of lunar regolith provides a cost-effective way to construct the lunar base. The melting and solidifying of lunar soil, especially under the vacuum environment on the Moon, are the fundamentals to achieve this. In this paper, lunar regolith simulant was melted and solidified at different temperatures under a vacuum, and the solidified samples' morphology, structure, and mechanical properties were studied. The results indicated that the density, compressive strength, and Vickers hardness of the solidified samples increased with increasing melting temperature. Notably, the sample solidified at 1400 degrees C showed excellent nanohardness and thermal conductivity originating from the denser atomic structure. It was also observed that the melt migrated upward along the container wall under the vacuum and formed a coating layer on the substrate caused by the Marangoni effect. The above results proved the feasibility of employing the solidified lunar regolith as a primary building material for lunar base construction.

The lunar base establishing is crucial for the long-term deep space exploration. Given the high costs associated with Earth-Moon transportation, in-situ resource utilization (ISRU) has become the most viable approach for lunar construction. This study investigates the sintering behavior of BH-1 lunar regolith simulant (LRS) in a vacuum environment across various temperatures. The sintered samples were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), along with nanoindentation, uniaxial compression, and thermal property tests to evaluate the microstructural, mechanical, and thermal properties. The results show that the sintering temperature significantly affects both the microstructure and mechanical strength of the samples. At a sintering temperature of 1100 degrees C, the compressive strength reached a maximum of 90 MPa. The mineral composition of the sintered samples remains largely unchanged at different sintering temperatures, with the primary differences observed in the XRD peak intensities of the phases. The plagioclase melting first and filling the intergranular pores as a molten liquid phase. The BH-1 LRS exhibited a low coefficient of thermal expansion (CTE) within the temperature range of - 150 degrees C to 150 degrees C, indicating its potential for resisting fatigue damage caused by temperature fluctuations. These findings provide technical support for the in-situ consolidation of lunar regolith and the construction of lunar bases using local resources.

Preparing regolith-based composites for 3D printing is crucial in lunar base construction, leveraging costeffective and mechanically favorable materials for lunar construction by utilizing lunar regolith as the reinforcing phase. This research focuses on developing lunar regolith simulant as a matrix for 3D printing, which is crucial for in-situ resource utilization on the Moon. Resin-based composites, well-established in aerospace, are explored for their simple manufacturing and robust properties. The formulation involves simulated regolithbased polymer for direct ink writing printing. Rheological properties, including yield stress and plastic viscosity, are characterized across various cementite-sand ratios and printing temperatures. The relationship between extrudability, the time interval of the printing material and its rheological attributes is investigated. Quantitative assessment of material buildability employs three-dimensional scanning of the printed parts. Freeze-thaw cycle tests explore its temperature resilience. The influence of varying the printing infill rate on printing efficiency and the performance of the printed parts was assessed. It was found that modulating the printing infill rate affects the efficiency and performance of parts, with a 1:4 cementite-sand ratio and a 40 degrees C print temperature demonstrating optimal printing workability. These findings offer an efficient scheme for the automated production of regolithbased epoxy composites with precise structural, temperature-resistant, and favorable mechanical properties.

The technology of 3D printing, referred to as additive manufacturing, is widely acknowledged as a transformative innovation that has the potential to supplant traditional processing methods in numerous domains. The present study showcases a quantitative assessment of the mechanical properties of moon dust, also known as Lunar Regolith Simulants (LRS), printed through vat polymerization. In this study, we conduct a thorough investigation and explore the effects of layer height [LH] (LH = 10 mu m, 20 mu m, 30 mu m, 40 mu m, 50 mu m, 60 mu m]), exposure time [ET] (ET = 3000 ms, 5000 ms, 7000 ms, 11,000 ms), and sintering impact [1075 degrees C, 1082 degrees C, 1083 degrees C, 1085 degrees C, 1086 degrees C, 1087 degrees C, 1090 degrees C] on the mechanical properties of printed structures. Herein, we utilize a 55 % volume suspension of LRS to print rod and block configurations via digital light printing [DLP] that are subsequently consolidated through sintering in ambient air. This 55 % LRS via vat polymerization approach has not been previously reported. The morphology of the simulant powders exhibited irregular and angular features. Our experimental results show that a 30 um (LH) with (ET) 11,000 ms exhibits maximum compressive and flexural strength of 330 MPa and 100 MPa at 1085 degrees C. The sintering atmosphere greatly affects the microstructure, macroscopic features, and mechanical strength of 3D-printed LRS, which reveals diverse chemical compositions and underlying reaction mechanisms. This sintering process improves particle bonding, resulting in densification and reduced voids within the 3D-printed structure. It is essential to optimize the annealing parameters to achieve the desired strength while avoiding excessive sintering that may cause dimensional distortions or structural defects. This innovative approach opens new possibilities for future space exploration and extraterrestrial construction.

The mechanical and thermal properties of the fabricated structures composed of lunar regolith are of great interest due to the urgent demand for in situ construction and manufacturing on the Moon for sustainable human habitation. This work demonstrates the great enhancement of the mechanical and thermal properties of CUG-1A lunar regolith simulant samples using spark plasma sintering (SPS). The morphology, chemical composition, structure, mechanical and thermal properties of the molten and SPSed samples were investigated. The sintering temperature significantly influenced the microstructure and macroscopic properties of these samples. The highest density (similar to 99.7%), highest thermal conductivity (2.65 W.m(-1).K-1 at 1073 K), and the best mechanical properties (compressive strength: 370.2 MPa, flexural strength: 81.4 MPa) were observed for the SPSed sample sintered at 1273 K. The enhanced thermal and mechanical properties of these lunar regolith simulant samples are attributed to the compact structure and the tight bonding between particles via homogenous glass.

The development and utilization of lunar resources are entering a critical stage. Immediate focus is needed on key technologies for in-situ resource utilization (ISRU) and lunar base construction. This paper comparatively analyzes the basic characteristics of lunar regolith samples returned from Chang'e-5 (CE- 5), Apollo, and Luna missions, focusing on their physical, mechanical, mineral, chemical, and morphological parameters. Given the limited availability of lunar regolith, more than 50 lunar regolith simulants are summarized. The differences between lunar regolith and simulants concerning these parameters are discussed. To facilitate the construction of lunar bases, this article summarizes the advancements in research on construction materials derived from lunar regolith simulants. Based on statistical results, lunar regolith simulant-based composites are classified into 5 types by their strengthening and toughening mechanisms, and a comprehensive analysis of molding methods, preparation conditions, and mechanical properties is conducted. Furthermore, the potential lunar base construction forms are reviewed, and the adaptability of lunar regolith simulant-based composites and lunar base construction methods are proposed. The key demands of lunar bases constructed with lunar regolith-based composites are discussed, including energy demand, in-situ buildability, service performance, and structural availability. This progress contributes to providing essential material and methodological support for future lunar construction. (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/).

Establishing a base on the Moon is one of the new goals of human lunar exploration in recent years. Sintered lunar regolith is one of the most potential building materials for lunar bases. The physical, mechanical and thermal properties of sintered lunar regolith are vital performance indices for the structural design of a lunar base and analysis of many critical mechanical and thermal issues. In this study, the HUST-1 lunar regolith simulant (HLRS) was sintered at 1030, 1040, 1050, 1060, 1070, and 1080 C. The effect of sintering temperature on the compressive strength was investigated, and the exact value of the optimum vacuum sintering temperature was determined between 1040 and 1060 C. Then, the microstructure and material composition of vacuum sintered HLRS at different temperatures were characterized. It was found that the sintering temperature has no significant effect on the mineral composition in the temperature range of 1030-1080 C. Besides, the heat capacity, thermal conductivity, and coefficient of thermal expansion (CTE) of vacuum sintered HLRS at different temperatures were investigated. Specific heat capacity of sintered samples increases with the increase of test temperature within the temperature range from -75 to 145 C. Besides, the thermal conductivity of the sintered sample is proportional to density. Finally, the two temperatures of 1040 and 1050 degrees C were selected for a more detailed study of mechanical properties. The results showed that compressive strength of sintered sample is much higher than tensile strength. This study reveals the effects of sintering temperature on the physical, mechanical and thermal properties of vacuum sintered HLRS, and these material parameters will provide support for the construction of future lunar bases. (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/).

The utilization of in-situ lunar resources through the additive manufacturing of lunar regolith (LR) has attracted considerable interest. Sintering of LR is considered a promising method for lunar construction due to its high utilization rate and excellent service stability. However, numerous studies have been carried out on Apollo series LRs with similar chemical compositions in air or inert gas atmospheres. The effects of the lunar ultra-high vacuum conditions and the complex chemical composition of LRs on the sintering process require extensive investigation. In this study, a self-developed Chang'E-5 lunar regolith simulant (LRS) with a high-Fe content was used as the only raw material to investigate its potential applicability for future lunar construction in vacuum environment. The effects of sintering temperature on the microstructure, linear shrinkage, bulk density, weight loss ratio, and mechanical and thermal expansion properties were investigated. The results show that the linear shrinkage and weight loss ratio increase with increasing sintering temperature. However, the bulk density and unconfined compressive strength (USC) initially increase and then decrease, with the sample sintered at 1075 degrees C giving the highest bulk density of 2.10 +/- 0.03 g/cm3 and a USC of 31.19 +/- 1.96 MPa. This is attributed to the transformation of the sample sintered at 1090 degrees C into a semi-porous material with many cracks. Furthermore, the mechanism of pore and crack formation was revealed. The coefficient of thermal expansion (CET) of the sintered samples is approximately 7x10-6 degrees C 1, which maintains a good service stability after cyclic temperature stress from room temperature up to 200 degrees C. Both the USC and CET of the sample sintered at 1075 degrees C are superior to those of common terrestrial concrete materials. This indicates that the vacuum sintering process appears feasible for the production of building materials with sufficient mechanical strength and thermal durability for lunar base construction.

NASA envisions a future where humans establish a thriving colony on the Moon by 2050. Plants will be essential for this endeavor, but little is known about their adaptation to extraterrestrial bodies. The capacity to grow plants in lunar regolith would represent a major step towards this goal by minimizing the reliance on resources transported from Earth. Recent studies reveal that Arabidopsis thaliana can germinate and grow on genuine lunar regolith as well as on lunar regolith simulant. However, plants arrest in vegetative development and activate a variety of stress response pathways, most notably the oxidative stress response. Telomeres are hotspots for oxidative damage in the genome and a marker of fitness in many organisms. Here we examine A. thaliana growth on a lunar regolith simulant and the impact of this resource on plant physiology and on telomere dynamics, telomerase enzyme activity and genome oxidation. We report that plants successfully set seed and generate a viable second plant generation if the lunar regolith simulant is pre-washed with an antioxidant cocktail. However, plants sustain a higher degree of genome oxidation and decreased biomass relative to conventional Earth soil cultivation. Moreover, telomerase activity substantially declines and telomeres shorten in plants grown in lunar regolith simulant, implying that genome integrity may not be sustainable over the long-term. Overcoming these challenges will be an important goal in ensuring success on the lunar frontier.