The exploration and study of water ice in the lunar polar regions are of great significance for understanding the origin and evolution of water and volatiles on the Moon, as well as for realizing in situ resource utilization for space exploration. In recent years, the detection of water ice in these regions has become a strategic priority in the competition among major countries, including the United States, China, and Russia, in the fields of lunar and deep space exploration. One of the primary scientific tasks for the Chang'E-7 (CE-7) lunar exploration mission is to detect and investigate water ice at the lunar south pole. In this work, the progress in the exploration and study of water ice in the lunar polar regions is summarized. The unresolved key scientific questions related to polar water ice are presented. Furthermore, the basic information and especially the scientific objectives about water ice detection of CE-7 mission are introduced. The remote sensing and in situ detection methods of water ice at the south pole are discussed based on the scientific payloads onboard the orbiter, rover, and mini-flying probe in the CE-7 mission.
Substantial evidence indicates that the Permanently Shadowed Regions (PSRs) at the lunar poles may harbor considerable water-ice resources mixed with lunar regolith. Understanding the mechanical and thermal properties of icy regolith is a prerequisite for elucidating the evolutionary mechanisms and exploitation strategies of lunar water-ice, and these key properties are closely related to the occurrence forms of water-ice within the porous regolith medium. Specifically, does water-ice exist as dispersed small particles (frost) within the regolith pores, or has it undergone ripening and coarsening, forming large crystals comparable in size to regolith grains? Currently, there is neither direct observational evidence nor theoretical research addressing this question. This knowledge gap also hinders the rational preparation of icy lunar regolith simulants. In this study, we derive a theoretical model of Ostwald ripening under rarefied conditions, demonstrating that clusters of small water-ice particles (frost) within lunar regolith pores will undergo material migration and locally aggregate into large crystals over geological timescales. We quantitatively investigate the ripening rates of water-ice particle clusters under different temperature conditions. The theoretical results indicate that water-ice on the surface of ultra-low temperature PSRs region (<100 K) can retain its initial deposition morphology for extended periods, whereas in warmer non-PSRs or subsurface regions (>120 K), water-ice particle clusters will undergo significant coarsening, forming large crystals comparable in size to regolith grains. Based on these findings, we can prepare lunar regolith simulants with water-ice particle sizes matching those of target icy regolith by adjusting temperature and ripening time. This study not only advances the theoretical understanding of lunar water-ice evolution mechanisms but also provides a critical theoretical foundation for research on the physical properties of icy regolith and the preparation of simulants, offering significant application value for the exploitation and utilization of lunar water-ice resources.
The exploration and utilization of lunar water and ice resources have become the core proposition supporting sustainable human extraterrestrial presence. This article analyzes the occurrence characteristics and remote sensing evidence of lunar soil water ice, sorts out the current status of technological development and utilization of lunar soil water ice, and highlights the difficulties and challenges of exploration and utilization technology. Based on the design criteria for the exploitation of lunar soil water and ice resources, this paper elaborates on four fundamental engineering issues related to the utilization of water and ice resources, and provides corresponding conceptual plans and key technologies. The research results of this article can provide reference for the development and utilization of water ice resources in China.
Lunar water ice is a critical resource for the construction of future lunar bases. However, constrained by the extreme environment of permanently shadowed regions, traditional drilling methods struggle to achieve low-power, low-drilling-pressure, and fidelity-preserving drilling. In this paper, an ultrasonic sampler suitable for drilling in lunar water ice frozen soil is designed and fabricated. The vibration mode of the ultrasonic horn is designed using finite element simulation software, and the actual output performance of the horn is verified. Simulated lunar regolith permafrost with a 10.0% water content is prepared, and its uniaxial compressive strength is measured to be 41 MPa. The discrete element simulation software PFC is used to simulate the mechanical properties of lunar water ice frozen soil, and the constitutive parameters are established. The drilling performance is evaluated through simulated drilling experiments on lunar regolith permafrost. The results show that under the same feed rate, the average drilling force is reduced by 52.0% when ultrasonic driving is applied, with a deviation of 10.5% from the simulation results.
Under the constraints of the extreme environment in the lunar polar regions and the low thermal conductivity of lunar soil particles, extracting water resources from icy lunar regolith faces significant technical challenges. This study established a microwave heating experimental system to investigate the technical methods for water resource extraction and collection from icy lunar regolith. Low-temperature Lunar Regolith Simulant (LRS) were prepared, and experimental tests were conducted to obtain the fundamental characteristics of water extraction and collection processes from microwave-heated icy LRS. The effects of microwave heating parameters and sample properties on water extraction efficiency were analyzed. Results indicate that microwaves can penetrate the entire LRS, enabling nearly uniform heating. The energy efficiency of microwave heating typically ranges between 2.5~6.0 W·h/g. Water extraction rate shows a positive correlation with total microwave energy input, and optimal ice-water extraction efficiency can be achieved by adjusting microwave power, heating temperature, and constant-temperature heating duration. Increased sample compaction enhances thermal conduction between water molecules and soil particles, reducing total energy input while improving water extraction rate. The average water collection rate in this system ranges from 0.53~1.59 g/min, increasing with the initial water content. This study provides a new route map for water exploitation in the lunar polar regions.
As deep space exploration missions progress, the extraction and utilization of in-situ lunar water ice resources will be crucial for the establishment of lunar bases and the sustainability of human presence. Microwave heating extraction, as an efficient and rapid extraction technology, has a broad application prospect. In this paper, for the microwave heating extraction process of lunar water ice, an electromagnetics model and a heat transfer model are constructed by decoupling the electromagnetic field from other physical processes. The extraction process under different power inputs is numerically simulated by using the finite element software COMSOL Multiphysics. The results show that: the maximum depth of microwave heating is basically the same as the depth of microwave penetration, and the effective heating range is the area where the modal value of the electric field strength is higher than 1/e times of the surface value; the quality of the extracted water ice is basically positively correlated with the input power of microwave, but the efficiency of the extraction decreases due to the influence of heat conduction in the low-power case; up to
This study aims to address the technical complexity associated with the low collection efficiency of water vapor during the in situ heat extraction of water ice in the lunar polar region. To this end, the study analyzes the influencing factors based on the heat and mass transfer characteristics of the frost layer porous medium. This is achieved through the kinetic model of the phase transition of the water vapor and the growth model of the condensing frost layer. The study's findings provide a theoretical foundation for the optimization of the condenser. A comparison and analysis must be conducted of the relationship between the particle size of aluminum beads and the water vapor flow rate through water vapor flow simulation. A validation platform has been configured to replicate the extreme environment on the Lunar surface. This platform will be utilized to conduct comparative tests on the water vapor condensation collection efficiency of aluminum bead structures with varying particle sizes. The findings indicate that the flow rate of water vapor within the condenser is directly proportional to the diameter of aluminum beads. A decrease in diameter results in a reduction in flow rate, thereby extending the heat exchange time between water vapor and the condenser. The correlation between the internal surface area of the water vapor condenser and its water vapor collection efficiency is positive. The utilization of aluminum beads with a small particle size can lead to a substantial enhancement in the internal surface area. However, the adoption of such aluminum beads is hindered by the potential for pore blockage, which can be caused by the aforementioned small particle size. The study offers a theoretical and experimental foundation for the design of a water vapor collection unit as part of an in-situ Lunar water ice resource extraction device.
The extraction and utilization of water resources in the permanent shadowed regions of the lunar polar regions is one of the key tasks for future lunar base construction. This study analyzed the formation mechanism and environment of frozen soils on the Moon, compared the preparation methods and tested the characterization of lunar soil simulants with temperatures below −180 ℃, analyzed the advantages and disadvantages of different collection and water extraction methods for frozen soils in the permanent shadow regions, proposed a water resource extraction system and key technologies suitable for future in-orbit verification, so as to provide technical references for future extraterrestrial water resource extraction tasks.
Significant water ice deposits are present in the permanently shadowed regions of the lunar poles, and the extraction of these water ice resources holds great scientific and practical value. This paper proposes a water ice extraction method using a thermal drill based on eddy current induction heating. The method involves drilling a high thermal conductivity drill bit into deep lunar regolith, heating the regolith externally via an induction coil, and transferring heat to the subsurface to evaporate water ice for extraction. To verify the feasibility of this approach, simulations were conducted on key parameters affecting the thermal drilling performance. Additionally, an experimental platform for induction heating of the thermal probe was established, and vacuum-environment heating tests with an empty drill bit were performed. The results demonstrate that this method can effectively transfer heat into the lunar regolith interior. This research provides technical groundwork for China's future extraction of water ice resources from lunar regolith.
Lunar polar water ice resources are critical for future lunar exploration, serving as essential life-support materials and propellant feedstock. In-situ water ice extraction technologies have become a strategic focus among leading space nations. To address the demand for efficient mining of water ice resources in permanently shadowed regions at lunar poles, this study proposes a multi-needle thermal extraction system design. This paper elaborates on the system architecture and functional characteristics, while numerical simulations investigate the effects of needle parameters and spatial distribution on water ice sublimation rates, validating the proposed approach. These research findings will provide significant technical support for in-situ resource utilization and lunar base construction.
