H2O extraction from remote icy lunar regolith using concentrated irradiation was investigated under high-vacuum and low-temperature conditions. The thermal sublimation of H2O(s) from packed beds of lunar regolith simulants was quantified with and without an indirect solar receiver for average concentrated irradiations of 37.06 f 2.66 and 74.62 f 3.57 kW/m2. The indirect solar receiver increased sublimation by an average of 18.7 % f 10.4 %, despite slower heating rates due to its increased thermal mass. Different average concentrated irradiations affected the heating rates and thermal gradients within the packed bed, but the impact on overall sublimation was not statistically significant. An inverse relationship between heating rates and normalized sublimation was also observed, where rapid sublimation near the heating elements led to the formation of a desiccated layer of regolith, which behaved as a thermal insulator and further limited heat transfer, reducing the sublimation efficiency. These findings provide key insights for optimizing in-situ resource utilization technologies, contributing to the development of efficient methods for extracting H2O from lunar regolith, which is essential for sustainable space exploration.

The exploration of the Moon necessitates sustainable habitat construction. Establishing a permanent base on the Moon requires solutions for challenges such as transportation costs and logistics, driving the emphasis on In-Situ Resource Utilization (ISRU) techniques including Additive Manufacturing. Given the limited availability of regolith on Earth, researchers utilize simulants in laboratory studies to advance technologies essential for future Moon missions. Despite advancements, a comprehensive understanding of the fundamental properties and processing parameters of sintered lunar regolith still needs to be studied, demonstrating the need for further research. Here, we investigated the fundamental properties of lunar regolith simulant material with respect to the stereolithography-based AM process needed for the engineering design of complex items for lunar applications. Material and mechanical characterization of milled and sintered LHS-1 lunar regolith was done. Test specimens, based on ASTM standards, were fabricated from a 70 wt% (48.4 vol %) LHS-1 regolith simulant suspension and sintered up to 1150 degrees C. The compressive, tensile, and flexural strengths were (510.7 +/- 133.8) MPa, (8.0 +/- 0.9) MPa, and (200.3 +/- 49.3) MPa respectively, surpassing values reported in previous studies. These improved mechanical properties are attributed to suspension's powder loading, layer thickness, exposure time, and sintering temperature. A set of regolith physical and mechanical fundamental material properties was built based on laboratory evaluation and prepared for utilization, with the manufacturing of complex-shaped objects demonstrating the technology's capability for engineering design problems.

Lunar ice is a strategically important resource due to its potential to enable in-situ production of propellants for in-space refueling. However, existing remote sensing data are insufficient to determine whether prospective ice deposits meet reserve criteria. This study applies value of information (VOI) theory to investigate the economic rationale for completing ground-based exploration for lunar ice reserves. By investigating a range of potential extraction and exploration scenarios, the analysis demonstrates the utility of linking VOI to cash flow models as a framework for evaluating future missions. This study finds that uncertainties in deposit composition and technology performance are primary factors undermining the business case. Lunar-sourced propellant could yield positive net present value (NPV) outcomes-even with low propellant prices and launch costs. In representative future scenarios, the VOI from ground-based exploration is likely to exceed mission costs, suggesting that such campaigns can be economically justified.

The construction of a lunar base requires a huge amount of material, which cannot be entirely transported from Earth. Therefore, technologies are needed to build with locally available resources, such as the lunar regolith. One approach is to directly melt the lunar regolith on the surface and under the vacuum condition of the Moon, using laser radiation. In this article, a lunar regolith simulant is laser beam melted to two-dimensional singlelayer-structures using different ambient pressures from 0.05 mbar to 2000 mbar, laser process parameters from 60 W to 100 W laser power, and 1 mm s- 1 to 3 mm s- 1 feed rates. Additionally, the influence of the ambient gas was investigated using argon as an air alternative. The results show that the ambient pressure on the Moon is not negligible when studying the melting processes of lunar regolith on Earth. With decreasing ambient pressure, the appearance of the melted regolith simulant varies from a shiny to a matt surface. At the highest laser energy density, the thickness of a single-layer increases from 2.6 +/- 0.4 mm to 5.3 +/- 0.3 mm and the porosity of the melted regolith increases from 17.2 % to 52.2 % with decreasing ambient pressure. Additionally, mechanical properties are determined using 3-point bending tests. The maximum bending strength decreases by 60 % with the increased ambient pressure from 10 mbar to 2000 mbar. Consequently, the development of in-situ resource utilization technologies, which process the lunar regolith directly on the lunar surface, must consider the ambient pressure on the Moon. Otherwise, the processes will not work as expected from the experiments in Earth-based laboratories.

Mars is increasingly considered for colonization by virtue of its Earth-like conditions and potential to harbor life. Responding to challenges of the Martian environment and the complexity of transporting resources from Earth, this study develops a novel geopolymer-based high-performance Martian concrete (HPMC) using Martian soil simulant. The optimal simulant addition, ranging from 30% to 70% of the total mass of the binders, was explored to optimize both the performance of HPMC and its cost-effectiveness. Additionally, the effects of temperature (-20 degrees C-40 degrees C) and atmospheric (ambient and carbonated) curing conditions, as well as steel fibre addition, were investigated on its long-term compressive and microstructural performance. Optimal results showed that HPMC with 50% regolith simulant achieved the best 7-day compressive strength (62.8 MPa) and the remarkable efficiency improvement, a result of ideal chemical ratios and effective geopolymerization reaction. Under various temperature conditions, sub-zero temperatures (-20 degrees C and 0 degrees C) diminished strength due to reduced aluminosilicate dissolution and gel formation. In contrast, specimens cured at 40 degrees C and 20 degrees C, respectively, showed superior early and long-term strengths, with the 40 degrees C potential for moisture loss related shrinkage cracking and reduced geopolymerization. Regarding the atmospheric environment, carbonation curing and steel fibre addition both improved the matrix compactness and compressive strength, with carbon-cured fibre-reinforced HPMC achieving 98.3 MPa after 60 days. However, long-term exposure to high levels of CO2 eventually reduced the fibres' toughening effect and caused visible damages on steel fibres.

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.

This review explores the development and potential applications of space concrete, a critical material for future extraterrestrial construction. Space concrete, adapted to withstand the harsh conditions of outer space, such as extreme temperatures, vacuum, microgravity, and radiation, offers a sustainable solution for building habitats and infrastructure on celestial bodies like the Moon and Mars. Emphasizing the innovative approaches in formulating space concrete, including the use of lunar and Martian soil as aggregates and the exploration of alternative binders to traditional water-based cement, this review highlights the significance of in-situ resource utilization (ISRU) and 3D printing technologies in advancing extraterrestrial construction. Additionally, the current designs and applications of space concrete structures are discussed. By providing a detailed analysis of the challenges faced in space construction and the latest advancements in material and structural research, the review underlines the pivotal role of space concrete in supporting space exploration and long-term habitat.

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/).

Recent discoveries of potential ice particles and ice-cemented regolith on extraterrestrial bodies like the Moon and Mars have opened new opportunities for developing technologies to extract water, facilitating future space missions and activities on these extraterrestrial body surfaces. This study explores the potential for water extraction from regolith through an experiment designed to test water recuperation from regolith simulant under varying gravitational conditions. The resultant water vapor extracted from the regolith is re-condensed on a substrate surface and collected in liquid form. Three types of substrates, hydrophobic, hydrophilic, and grooved, are explored. The system's functionality was assessed during a parabolic flight campaign simulating three distinct gravity levels: microgravity, lunar gravity, and Martian gravity. Our findings reveal that the hydrophobic surface demonstrates the highest efficiency due to drop-wise condensation, and lower gravity levels result in increased water condensation on the substrates. The experiments aimed to understand the performance of specific substrates under lunar, Martian, and microgravity conditions, providing an approach for in-situ water recovery, which is crucial for establishing economically sustainable water supplies for future missions. To enhance clarity and readability, in this paper, H2O will be referred to as water.

The lunar poles are thought to contain vast ice deposits that could be beneficial to future space exploration efforts. However, it is not well characterized how water ice content affects regolith and dust physical properties. In order to develop suitable technologies that can operate safely in the cryogenic regolith, testing should be conducted in simulated regolith. We present a new production method for lunar permanently shadowed regions (PSRs) icy regolith simulant. We build on an existing lunar highlands simulant, by adapting it for lunar poles, where water ice might be present in PSRs. We have demonstrated a production concept using controllable simulant and water flow rates to make granular icy simulant with variable water ice content. We found that with this production method, icy simulant has a porosity of 0.6 to 0.7, that persists even after dehydration. (c) 2024 COSPAR. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).