The Lunar Economy – Unlocking Access to the Solar System

As the only natural satellite of the Earth, the Moon is the first target for human space exploration, due to its unique location, highly characteristic environmental resources and abundant material resources. The Earth-Moon system is the proving ground for the exploration of the solar system, and the Moon is a transit point towards farther deep space. Lunar science plays an important role in promoting the development of space science. The development and utilization of lunar resources is of great significance to the sustainable development of mankind. In recent years, China’s lunar exploration has achieved remarkable achievements. After completing the three steps strategy of “orbiting, landing and sample return”, it will aim to better serve the lunar scientific exploration and in situ resource utilization (ISRU), to enhance human scientific cognition and expand Human living space, and to serve the sustainable development of human society. This paper reviews the status and trend of Chinese and international lunar exploration, and summarizes the main tasks, cutting-edge scientific questions and key technologies involved in future lunar exploration and puts forward recommendations for the development of the Chinese lunar exploration. Driven by lunar scientific exploration and lunar ISRU, the International Lunar Research Station (ILRS) aims to create infrastructure and shared platforms for solving key space science questions, effectively using lunar resources, and developing the Earth-Moon Economic Circle. In this article, the main mission requirements, and functional architecture of the station are analyzed. A three-step construction plan is proposed, involving (1) making good use of planned missions; (2) coordinating home and abroad missions; and (3) seeking for joint missions. In the first stage, relying on series missions of the fourth phase of China Lunar Exploration Program, we will carry out international cooperation and build up the basic type of the ILRS with capabilities of exploration under a long-term scale and complex environmental conditions. The ILRS will contribute to polar region scientific exploration, ISRU, and application verification for the future expansion. In the second stage, international lunar missions will be coordinated with the objective of expanding the scale, and the technical and scientific activities of the ILRS, therefore making a breakthrough in multi-national and multi-module collaborative work and in integration management or other key technologies. Key technologies, including the long-term operation and guarantee of future scientific research stations, and the application of lunar resource, will be mastered. In the third stage, international partners will contribute to upgrade the station in support of long-term and large-scale scientific exploration, technical experiments and the utilization of lunar resources by jointly investment of new missions. New era of human space exploration will be cultivated, and space physics, astronomy, planetary geology, planetary chemistry and other disciplines will be promoted by international cooperation. International cooperative methods planning integration, joint demonstration, mission design, technical cooperation, collaborative implementation, and achievement sharing are analyzed, all of which paving the way for the demonstration and implementation of the international big scientific projects the ILRS. At present, ILRS has become China’s first batch of international major scientific engineering cultivation projects. Along with international partners, China will carry out scientific objective research, engineering feasibility demonstration and joint implementation plan. Organizational management models and operating mechanisms will be proposed, international expert team and international implementation team will be established, on the basis of which the cultivation of the large-scale scientific project the ILRS will be completed under the principle of wide consultation, joint contribution and shared benefits.

Simulating lunar highlands regolith profiles on Earth to inform infrastructure development and ISRU activities on the Moon

To maximize the sustainability of future space missions, the utilization of local resources available on the Moon or Mars, also known as in-situ resource utilization (ISRU), is crucial to develop infrastructures such as habitation modules, power generation, and energy storage facilities.1–3 This work presents a perspective aiming to introduce the future of batteries manufacturing on the lunar and martian environment from ISRU materials. Based on the composition of the lunar and martian soil,4–7 the choice of the battery technology and materials for the different battery components (electrodes, electrolyte, current collectors and packaging) are examined. The motivations for selecting additive manufacturing technologies as a unique approach to support human operations in space, on the surface of the Moon or Mars, and any other locations where cargo resupply is not as readily available, as well as the need for high resolution multi-material printing methods, are discussed. Additive manufacturing paves the way to three-dimensional rechargeable battery architectures with enhanced specific surface area, three-dimensional ion diffusion, and improved power performances, while also allowing the development of shape-conformable batteries to maximize the energy storage within the final application.8–15 The in-space additive manufacturing process of shape-conformable batteries using in-situ resources is in direct alignment with the NASA’s objectives to demonstrate in-space autonomous manufacturing and assembly of complete systems by 2030, and to enable Humans survival, explore deep space, and visit planetary surfaces by 2040.16 Such initiatives also contribute to reducing power-related payload weight and volume in future missions, thus reducing the risk for long term Moon or even Mars missions where rapid resupply will be logistically infeasible. In this context, this presentation will provide a perspective of what is required to 3D print batteries on lunar and martian surfaces,17 an overview of our ongoing project dedicated to AM of sodium-ion batteries from resources available on the Moon and Mars and our recent work on 3D printing of TiO2 negative electrode material by means of the vat photopolymerization process.18 (1) Anand, M. et al. A Brief Review of Chemical and Mineralogical Resources on the Moon and Likely Initial in Situ Resource Utilization (ISRU) Applications. Planet. Space Sci. 2012, 74 (1), 42–48.(2) Edmunson. Building a Sustainable Human Presence on the Moon and Mars. New Horizons Summit.(3) McMillon-Brown, L. et al. What Would It Take to Manufacture Perovskite Solar Cells in Space? ACS Energy Lett. 2022, 7 (3), 1040–1042.(4) Heiken, G. et al. Lunar Sourcebook: A User’s Guide to the Moon; CUP Archive, 1991.(5) Dreibus, G. et al. Lithium and Halogens in Lunar Samples. Philos. Trans. R. Soc. Lond. A 1977, 285 (1327), 49–54.(6) Taylor, G. J. The Bulk Composition of Mars. Geochem. Explor. Environ. Analy. 2013, 73 (4), 401–420.(7) Yoshizaki, T. et al. The Composition of Mars. Geochim. Cosmochim. Acta 2020, 273, 137–162.(8) Maurel, A. et al. Highly Loaded Graphite-Polylactic Acid Composite-Based Filaments for Lithium-Ion Battery Three-Dimensional Printing. Chem. Mater. 2018, 30 (21), 7484–7493.(9) Maurel, A. et al. Considering Lithium-Ion Battery 3D-Printing via Thermoplastic Material Extrusion and Polymer Powder Bed Fusion. Additive Manufacturing 2020, 101651.(10) Martinez, A. C. et al. Additive Manufacturing of LiNi1/3Mn1/3Co1/3O2 Battery Electrode Material via Vat Photopolymerization Precursor Approach. Sci. Rep. 2022, 12 (1), 1–13.(11) Maurel, A. et al. Overview on Lithium-Ion Battery 3D-Printing By Means of Material Extrusion. ECS Trans. 2020, 98 (13), 3–21.(12) Maurel, A. et al. Toward High Resolution 3D Printing of Shape-Conformable Batteries via Vat Photopolymerization: Review and Perspective. IEEE Access 2021, 9, 140654–140666.(13) Maurel, A. et al. Ag-Coated Cu/Polylactic Acid Composite Filament for Lithium and Sodium-Ion Battery Current Collector Three-Dimensional Printing via Thermoplastic Material Extrusion. Frontiers in Energy Research 2021, 9 (70). https://doi.org/10.3389/fenrg.2021.651041.(14) Ragones, H. et al. Towards Smart Free Form-Factor 3D Printable Batteries. Sustainable Energy & Fuels 2018, 2 (7), 1542–1549.(15) Egorov, V. et al. Evolution of 3D Printing Methods and Materials for Electrochemical Energy Storage. Adv. Mater. 2020, 32 (29). https://doi.org/10.1002/adma.202000556.(16) Murphy, P. STMD’s New Strategic Framework Update, 2017. https://www.nasa.gov/sites/default/files/atoms/files/336429-508-to5_nac_dec_2017_strategicplanningintegration_tagged.pdf.(17) Maurel, A. et al. What Would Battery Manufacturing on the Moon and Mars Look Like? (submitted).(18) Maurel, A. et al. 3D Printed TiO2 Negative Electrodes for Sodium-Ion and Lithium-Ion Batteries Using Vat Photopolymerization (submitted).

With NASA's emphasis on lunar exploration through the Artemis program, novel scientific objectives have been formulated to enhance our understanding of the Solar System's historical context, particularly the evolution of the Earth-Moon system. Simultaneously, the establishment of a permanent human presence on the Moon is proposed as a primary objective within the Artemis program, with the achievement of this goal hinging on in-situ resource utilization (ISRU) of lunar materials. Effective ISRU needs methodologies for chemical analysis and selecting appropriate lunar materials in-situ. To facilitate these tasks, the deployment of sensitive instrumentation capable of determining the element and isotope composition of lunar materials is imperative.In this contribution, we present the current progress in developing a reflectron-type time-of-flight laser ablation ionisation mass spectrometer (RTOF-LIMS) to allow for direct sensitive chemical microanalysis of lunar regolith grains in-situ on the lunar surface. This LIMS system will operate in the lunar south pole region on a CLPS mission within NASA’s Artemis program.The contribution will provide a general overview of the instrument and focus primarily on the design and operations of the sample handling system (SHS). Furthermore, we will discuss the results of experiments conducted on lunar regolith simulant. These experiments were performed using a prototype LIMS system to validate the feasibility of the SHS. This prototype system has capabilities representative of the flight instrument currently in development regarding the mass analyser and optical sub-system. The laboratory and flight optical sub-systems are based on a microchip Nd:YAG laser system (~ 1.5 ns pulse width, λ = 532 nm, 100 Hz laser pulse repetition rate, laser irradiance ~ 1 GW/cm2), and custom-made laser optics to achieve a focal spot on the sample surface of ~20 μm. Consequently, the conducted measurements can serve as a qualification baseline for the flight instrument during ground-based tests.(1) P. Keresztes Schmidt et al., Sample handling concept for in-situ lunar regolith analysis by laser-based mass spectrometry, IEEE Aerospace Conference, 2024, submitted(2) P. Wurz et al., In Situ Lunar Regolith Analysis by Laser-Based Mass Spectrometry, IEEE Aerospace Conference, 2023, 1-10(3) P. Keresztes Schmidt, A. Riedo, P. Wurz, Chimia 2022, 76, 257(4) A. Riedo, A. Bieler, M. Neuland, M. Tulej and P. Wurz, J. Mass Spectrom., 2013, 48, 1-15(5) P. Wurz, M. Tulej, A. Riedo, V. Grimaudo, R. Lukmanov, and N. Thomas, IEEE Aerospace Conference, 2021, 50100, 1-15.

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.

Lunar dust, the finest fraction of lunar regolith, has undergone important space weathering on the Moon. It not only serves as a record of the evolution of the lunar surface environment and the modification of mineral properties, but also influences the lunar surface environment through dust transport. Our current understanding of the properties and transport mechanisms of lunar dust on the lunar surface, however, remains limited. With rapid development of lunar exploration, it is necessary to further study the problem and meet the need of future lunar exploration missions. The lunar surface is the primary environmental space where uncrewed lunar rover activity, crewed lunar exploration, and lunar base construction take place. The lunar dust will distribute in such a space area due to electrostatic lifting and impacted sputtering, which will pose a threat to lunar surface exploration activities. In addition, lunar dust transport is closely related to lunar horizon glow, lunar swirl, and lunar magnetic anomaly. Understanding the properties and transport mechanisms of lunar dust is key to comprehending the formation of these scientific phenomena. Therefore, a systematic and in-depth investigation of lunar dust properties and dust transport patterns is urgently required to advance lunar science and implement lunar exploration projects. In this study, we summarize the physical and chemical properties of lunar dust and our understanding of dust transport on the lunar surface, identify remaining challenges and issues in the study of lunar dust, and offer perspectives on this research field.

Unlike the Earth, the Moon lacks is not protected from the atmosphere and global magnetic field, and will be directly exposed to complex radiation environments such as high-energy cosmic rays, solar wind, and the Earth’s magnetotail plasma. The surface of the Moon is covered with a thick layer of lunar soil, and the particles in the soil with a diameter between 30 nm–20 μm are called lunar dust. In the complex environments such as solar wind or magnetotail plasma, lunar dust carries an electric charge and becomes charged lunar dust. Charged lunar dust is prone to migration under the action of the electric field on the lunar surface. Charged migrated lunar dust is easy to adhere to the surface of instruments and equipment, resulting in visual impairment, astronauts’ movement disorders, equipment mechanical blockage, sealing failure, and material wear, which affects the lunar exploration mission. As an important lunar exploration landing site, the lunar south pole receives special solar radiation and produces a special dust plasma environment due to its special location. In order to provide an environmental reference for lunar south pole exploration, it is necessary to explore the characteristics of the dust plasma environment in the lunar south pole and its impact. In view of the lunar south pole environment, The Spacecraft Plasma Interactions Software (SPIS) software developed by the European Space Agency is used to carry out modelling and simulation in this work. Through the simulation, the logarithmic distribution of the lunar dust space density in a range of 0–200 m at the lunar south pole, the potential distribution near the lunar surface, and the spatial distribution characteristics of plasma electrons and ions are obtained. The obtained lunar dust space density and lunar surface potential are similar to the previous theoretical derivation and field detection data, so the simulation results have high reliability. The spatial potential distribution and the spatial density distribution of electrons and ions in the lunar environment with and without lunar dust are compared. Finally, the conclusions can be drawn as follows. The space potential increases with altitude increasing. The potential at 0–10 m near the lunar south pole is about –40 V, and the space potential at 100 m is about –20 V. The density of lunar dust in an altitude range below 10 m is 10<sup>7.22</sup> m<sup>–3</sup>–10<sup>4.66</sup> m<sup>–3</sup>. The electron density in the dust plasma near the lunar surface is 10<sup>5.47</sup> m<sup>–3</sup>, and the ion density is 10<sup>6.07</sup> m<sup>–3</sup>, and both increase with altitude increasing. Charged lunar dust affects the spatial distribution of lunar dust, mainly through affecting the distribution of the space electric field, which leads to difference in electron distribution, but has little effect on ions.

A moderate-Ti lunar mare soil simulant: IGG-01

In situ resource utilisation (ISRU) refers to the extraction and use of local materials, and numerous ISRU techniques have been proposed for use on the Moon. Hydrogen reduction of iron oxide-bearing minerals in the lunar regolith, such as ilmenite, has long been suggested as a potential method for producing water on the Moon to support exploration. Generally, reduction of lunar regolith has been proposed and tested in gas-flowing systems which utilise pumps to re-circulate gases (herein described as dynamic systems), and have been trialled in terrestrial laboratory and simulated environments. However, such technologies have yet to be validated on the lunar surface. An alternative to the dynamic reactor is a static system which utilises a cold finger to condense water from the vapour phase, negating the need for a more complex system where gases are continuously pumped away. The PROSPECT Sample Processing and Analysis (ProSPA) instrument is one such static system that is to be used to measure volatiles in the lunar regolith as a payload onboard the Luna-27 lander. Previous work using a breadboard model of ProSPA led to the development and optimisation of a procedure for extracting water from ilmenite. The present work describes the application of these procedures to the reduction of a lunar simulant (NU-LHT-2M), a lunar meteorite (NWA 12592), and two Apollo soils (10084 and 60500). Three 45 ​mg samples of each material type were reacted in a furnace at 1000 ​°C for 4 ​h in the presence of approximately 420 ​mbar of hydrogen. All samples reduced to some extent, with the Apollo mare soil (10084) producing the highest average yield of 0.94 ​wt % O2; this compares favourably to the yields of ~3–4 ​wt % O2 by other more optimised demonstrations of O2 extraction from Apollo soils. Samples with higher ilmenite content produced higher yields, however, pyroxene and olivine within the samples also showed some minor reduction. The results demonstrate that a static system such as ProSPA is capable of reducing lunar regolith of various compositions and producing measurable yields of water. The technique is therefore appropriate for performing in situ resource utilisation experiments at the lunar surface. The simple and small scale technique is also appropriate for use in evaluating the grade of potential feedstock for the production of water by hydrogen reduction on the lunar surface.

A universal framework for Space Resource Utilisation (SRU)

    The Moon is sometimes also called the "eighth continent" of the Earth. Determining how to utilize cis-lunar orbital infrastructures and lunar resources to carry out new economic activities extended to the space of the Earth-Moon system is one of the long-term goals of lunar exploration activities around the world. Future long-term human deep-space exploration missions to the Moon, on the Moon surface or using the Moon to serve farther destinations will require the utilization of lunar surface or asteroid resources to produce water, oxygen and other consumables needed to maintain human survival and to produce liquid propellant for the supply of spacecraft on the lunar surface. In complement to exploration activities, Moon tourism in cis-lunar orbit and on the lunar surface will become more and more attractive with the increase of  human spaceflight capacity and the development of commercial space activities. However, the development of a sustainable Earth-Moon ecosystem requires that we solve the following five problems:(1)How to design alow-cost cis-lunar space transportation capacity? To find an optimal solution, one must compare direct Earth-Moon flight modes with flights based on the utilization of space stations, and identify the most economical spacecraft architectures.(2)How to design an efficient set ofcis-lunar orbital infrastructures combining LEO space stations, Earth-Moon L1/L2 point space stations and Moon bases for commercial tourism, taking into account key issues such as energy, communications and others?(3)Significant amounts ofliquid oxygen, water, liquid propellant and structural material will be needed for human bases, crew environmental control and life support systems, spacecraft propulsion systems, Moon surface storage and transportation systems. How to  design in-situ resources utilization (ISRU) of the Moon, including its soil, rocks and polar water ice reservoirs, to produce the needed amounts?(4) How to simulate on the Earth surface the different components and key technologies that will enable a future long-term human residence on the Moon surface?(5). How to accommodate the co-development of public and commercial space and foster international cooperation? How can space policies and international space law help this co-development?    China has made rapid progress in robotic lunar exploration activities in the last 20 years, as illustrated by the recent discoveries provided by the Chang'e-4 lander on the far side of the Moon. By 2061, China will have gone into manned lunar exploration and built Moon bases. In preparation for this new phase of its contribution to space exploration, lunar surface simulation instruments have been built in Beijing, Shenzhen and other places in China. A series of achievements have been made in the field of space life sciences . An ambitious project to establish a large Moon base simulation test field, the Lunar Base Yulin (LBY) project, currently in its design phase in Yulin, Shaanxi Province in China, will allow the verification of key relevant technologies.    By the 2061 Horizon, we believe that international cooperation and public-private partnership will be key elements to enable this vision of a new, sustainable cis-lunar space economy.

Hydrogen reduction of ilmenite: Towards an in situ resource utilization demonstration on the surface of the Moon

Water permeability of sunlit lunar highlands regolith using LHS-1 simulant

Thermodynamic analysis of combined heating and power system with In-Situ resource utilization for lunar base

Throughout the last decade a renewed interest for lunar space exploration has been expressed through the announcements of many ambitious missions such as Artemis. Annually the Space Station Design Workshop (SSDW) tasks students and young professionals to design a space station concept in a con-current engineering environment. In line with the elevated interest on the Moon this year's SSDW was centred around a self-sustainable lunar habitat. This paper presents the conceptual design of Team Blue at the SSDW 2021. Advanced Moon Operations and Resource Extraction (AMORE) is conceptu-alized as a public-private cooperation for the creation of a lunar platform that acts as an outpost for human exploration and robotic In-situ Resources Utilization (ISRU). AMORE’s proposed location is near the rim of Shackleton Crater at the Lunar South Pole. This location provides opportunities in science and ISRU and favourable sun coverage and thermal conditions. The terrain offers a natural shield for debris and storage advantages for ISRU. The mission architecture allows for incremental crew size increase through a modular dome structure, an initial prioritization of ISRU and a sustainable resource management strategy. Based on the identified system requirements, the initial configuration envisions one core module and two modular structures that would serve as greenhouses or living spaces. The phasing of the base assembly is designed to allow for adequate conditions of an increasing crew size capacity. The greenhouse modules are designed to provide all required oxygen and most required food supply. The modules are constructed using lightweight inflatable structures, while a regolith shell will provide radiation as well as thermal and micrometeorite protection. For reliable communication, a cus-tom relay network named Lunar Earth Telecommand Telemetry Relay (LETTER) is proposed. The mis-sion architecture analysis includes several methods to financially utilize the mission. These include a range of services on the lunar surface such as training facilities for deep space missions, leasing habitats to other Moon explorers, and performing scientific and technological demonstrations. A variety of rovers will be used throughout the mission that will assist in various aspects. In addition to this, a scalable hybrid power generation system that utilizes the abundant sunlight and nuclear energy assures a suffi-cient power supply throughout the entire mission lifetime. This research presents a holistic architecture for a Moon base, which provides an approach to initially utilize the Moon. Within this context, the mission concept is primarily based on already existing or currently in-development technologies. Hence, AMORE offers an approach for a financially and technologically feasible as well as a continuous and expandable human presence on the lunar surface