Lunar Water Research Articles

Driving innovation in lunar water purification technology Learn about how the UK Space Agency’s International Bilateral Fund (IBF) supported the UK-Canada Aqualunar Challenge to promote advancements in lunar water purification technology. Later this decade, humans are expected to set foot on the Moon once again. This time, the aim is not a short visit but longer stays – weeks, perhaps months – to carry out scientific research and prepare for exploration beyond our celestial neighbour. These ambitions bring new challenges, and one of the most fundamental is also the most familiar: water.

The Moon’s unique environment, strategic position, and resource abundance make it a key target for deep space exploration. As lunar missions evolve from research to long-term habitation, leveraging local resources is essential to reduce dependence on Earth-based supply chains. Despite significant studies on the lunar environment and in-situ resource utilization (ISRU), a unified framework that integrates these findings remains lacking. This article addresses this gap by systematically reviewing and synthesizing current research to support sustainable lunar development. It first explores the use of extreme lunar environmental factors such as thermal gradients, weak magnetic fields, subsurface cavities, and geographic advantages. It then examines lunar water and mineral resource development, highlighting methods for detection, extraction, purification, and storage, alongside strategies for utilizing various minerals. The article further reviews recent progress in in-situ manufacturing, construction technologies, energy regeneration, and closed-loop life-support systems vital for lunar base establishment. These advances are crucial for creating sustainable infrastructure and maintaining life on the Moon. Finally, the paper outlines the challenges and limitations associated with ISRU and offers perspectives on future directions, aiming to inform the design of next-generation lunar missions and facilitate permanent human presence on the Moon.

A lunar water ice high-conservation drilling system using frozen carbon dioxide spray cooling method: a numerical investigation

Thermal prospecting for lunar water with a percussive hot cone penetrometer

Abstract Previous studies have reported the existence of water ice in the lunar polar regions, but estimations of water ice using different methods vary in certainty, precision, location, and abundance. Spectral analysis is one of the major ways for estimating lunar water ice abundance. However, low spatial resolution and signal-to-noise ratio are the disadvantages of hyperspectral images. In this study, the images captured by the multi-band imager (MI), characterized by higher spatial resolution and signal-to-noise ratio than hyperspectral images, onboard the Japanese Moon orbiter Selenological and Engineering Explorer (SELENE), are used to retrieve water ice in lunar polar regions. We analyzed reflectance in near-infrared bands after topographic correction to reduce the misinterpretation of the properties of the lunar surface. Through qualitative spectral analysis and quantitative water ice retrieval, the water ice abundance of sunlit areas in Shackleton Crater, de Gerlache Rims 1 and 2, Connecting Ridge, Connecting Ridge extension, and Peak Near Shackleton are obtained. The sunlit inner wall of Shackleton Crater has the highest possibility to contain water ice among the four regions, the estimated abundance ranges from 2 to 3 wt.%, which is consistent with previous studies in terms of order of magnitude. Reproducibility test suggests that the parallax effect of MI is small to ensure robust conclusions. When artificial noise was introduced, water ice abundance variations were limited to 1 wt.% in only a few areas, revealing that the results exhibit robustness against noise interference.

This study reveals the dynamic flexibility of the intramolecular H-O bond under perturbations (pressure, temperature, coordination, and electric field), challenging its conventional rigidity and proton dynamic mobiity. By integrating bond nature index (m) analysis, tight-binding theory, and perturbation-resolved phonon spectroscopy (PRS), we quantify perturbation-driven changes in H-O bond length, energy, vibrational stiffness, O 1s core-level energy, and O:H nonbonding distance. A spectroscopic database correlates H-O bond relaxation and energy transfer in water, ice, hydroxides, and extraterrestrial systems (e.g., lunar water), capturing anomalies such as bond elongation under compression and contraction upon heating. These results redefine classical two-body hydrogen bonding models by emphasizing cooperative O:↔:O coupling and bond adaptability. Our approach enables direct extraction of bond parameters from spectral data, advancing predictive models for phase behavior and energy dynamics in hydrogen-bonded networks across chemistry, materials science, and planetary research.

The Moon very likely has polar caps, but not as conspicuous as the Earth or Mars; the Moon’s caps must be hidden under the surface. The southern polar cap is probably more aquiferous than the northern one. Our indication of ground water at the poles has been obtained by a remote sensing method. We use the gravity aspects, namely the combed strike angles, derived from a global gravity field model of the Moon (now providing the ground resolution ∼10 km already sufficient for this purpose). We cannot estimate the absolute amount of the lunar water, only the contrast between the polar areas and the other regions; the contrast is high, statistically significant – to 8 times more groundwater at the poles. For the southern polar zone, we confirm the results achieved by others, and we do it in a completely independent way. The lunar water is necessary for future permanent human missions on the Moon, like Artemis; they will start near the southern pole. Thus, our findings would have immediate applications. Observe and download: https://www.asu.cas.cz/~jklokocn/MOON25_supplements/

Value of Information for Lunar Ice Exploration

Distinguishing the origin of lunar water ice requires in situ isotopic measurements with high sensitivity and robustness under extreme lunar conditions; however, challenges such as uncertain water contents and isotopic fractionation induced by regolith particles restrict isotopic analysis. Herein, we present a miniaturized tunable diode laser absorption spectrometer (TDLAS) developed as the core prototype for the Chang'E-7 Lunar Soil Water Molecule Analyzer (LSWMA). The wavelength range of the instrument is 3659.5-3662.0 cm-1, and the system integrates a Herriott cell for stable multi-isotope (H216O, H218O, H217O, and HD16O) detection and employs regolith samples of known isotopic experiments to quantify adsorption-induced fractionation. Performance evaluations demonstrated a dynamic water detection range of 0.01-2 wt % and isotope precision up to 1.3‰ for δD (30.5 s), 0.77‰ for δ18O (36 s), and 0.75‰ for δ17O (21.5 s) with extended averaging. Repeated injections of three types of standard water revealed a volume-dependent deviation (ΔδD up to -59.5‰) attributed to multilayer adsorption effects, while simulated lunar soil experiments identified additional isotopic fractionation (ΔδD up to -12.8‰) caused by particle binding. These results validate the ability of the spectrometer to resolve subtle isotopic shifts under lunar conditions, providing critical data for distinguishing water origins and advancing future resource utilization strategies.

Abstract Aimed at the technical challenge of low water vapor collection efficiency in the in-situ thermal extraction of lunar polar water ice, this study, based on the heat and mass transfer characteristics of frost layer porous media, proposes a solution to enhance the gas-solid phase transition rate by optimizing the internal surface area of the water vapor collection unit. Through the establishment of a water vapor condensation dynamics model under vacuum and low-temperature conditions, the coupling effects of frost layer porosity and temperature field on the mass transfer process are revealed. A verification platform simulating the extreme lunar surface environment was constructed, and comparative experiments on different aluminum bead filling structures were conducted. The results indicate that the larger the internal surface area of the device, the higher the water vapor collection efficiency; the use of small-diameter aluminum beads significantly increases the internal surface area, but excessively small diameters may lead to pore blockage. The initial stage of water vapor collection is one of the key stages of mass transfer, where water vapor first comes into contact with the inner surface of the collection structure and undergoes a gas-solid phase change that affects the continued performance of the collection device. This research provides theoretical and experimental foundations for the design of water vapor collection units in in-situ lunar water ice extraction devices.

This paper presents an ultrasonic sampling penetrator with a staggered-impact mode, which has been developed for the extraction of lunar water ice. A comparison of this penetrator with existing drilling and sampling equipment reveals its effectiveness in minimizing disturbance to the in situ state of lunar water ice. This is due to the interleaved impact penetration sampling method, which preserves the original stratigraphic information of lunar water ice. The ultrasonic sampling penetrator utilizes a single piezoelectric stack to generate the staggered-impact motion required for the sampler. Finite element simulation methods are employed for the structural design, with modal analysis and modal degeneracy carried out. The combined utilization of harmonic response analysis and transient analysis is instrumental in attaining the staggered-impact motion. The design parameters were then used to fabricate a prototype and construct a test platform, and the design’s correctness was verified by the experimental results. In future sampling of lunar water ice at the International Lunar Research Station, the utilization of the ultrasonic sampling penetrator is recommended.

Abstract We have used molecular dynamics (MD) simulations to better understand the role of solar wind (SW) implanted hydrogen and micrometeoroid impacts on the lunar water cycle. Our simulations consider both the effect of initial hydrogen implantation profile along with the impact characteristics of the micrometeoroid (angle, size). Results show that water formation is strongly influenced by the initial depth location of hydrogen in the lunar soil, along with the impactor's characteristics. When hydrogen is distributed (instead of near surface) we find that nearly all of the water formed after a micrometeoroid impact was retained in the substrate. We also observe an increase in water production when micrometeoroids impact the surface at a normal angle compared to more glancing oblique impacts. In contrast, when micrometeoroids impact the surface of a substrate with near surface hydrogen we observe water loss characteristics and little retention. We also use these models to study the mechanism of water production within the substrate.

Optimizing thermal mining of lunar water ice: Numerical simulation of heating rod configuration and temperature control

Abstract We present the first full‐wavelength numerical simulations of the electric field generated by cosmic ray impacts into the Moon. Billions of cosmic rays fall onto the Moon every year. Ultra‐high energy cosmic ray impacts produce secondary particle cascades within the regolith and subsequent coherent, wide‐bandwidth, linearly‐polarized radio pulses by the Askaryan Effect. Observations of the cosmic ray particle shower radio emissions can reveal subsurface structure on the Moon and enable the broad and deep prospecting necessary to confirm or refute the existence of polar ice deposits. Our simulations show that the radio emissions and reflections could reveal ice layers as thin as 10 cm and buried under regolith as deep as 9 m. The Askaryan Effect presents a novel and untapped opportunity for characterizing buried lunar ice at unprecedented depths and spatial scales.

This study investigates the detectability of a putative layer of regolith containing water ice in the lunar polar regions using ground penetrating radar (GPR). Numerical simulations include realistic variations in the relative permittivity of the lunar regolith, considering both density and, for the first time, the effects of temperature on permittivity profiles. We follow the case of previous theoretical studies of water migration, which suggest that water ice accumulates at depths ranging from a few centimeters to tens of centimeters, appropriate depths to explore using GPR. In particular, frequency-modulated continuous wave (FMCW) radar is well-suited for this purpose due to its high range resolution and robust signal-to-noise ratio. This study evaluates two scenarios for the presence of lunar water ice: (1) a layer of regolith containing water ice at a depth of 5 cm, with a thickness of 5 cm, and (2) a layer of regolith containing water ice at a depth of 20 cm, with a thickness of 10 cm. Our computational results show that FMCW GPR, equipped with a dynamic range of 90 dB, is capable of detecting reflections from the interfaces of these layers, even under conditions of low water ice content and using antennas with low directivity. In addition, optimized antenna offsets improve the resolution of the upper and lower interfaces, particularly when applied to the surface of ancient crater ejecta. This study highlights the critical importance of understanding subsurface density and temperature structures for the accurate detection of water-ice-bearing regolith layers.

Abstract Various active and passive orbital measurements have provided evidence for surficial water ice within some lunar permanently shadowed regions (PSRs), especially from near-infrared observations by the M3 instrument. However, radar identification of lunar ice has so far remained ambiguous. Here, we examine the radar-inferred dielectric properties of lunar PSRs and illuminated craters to investigate the potential for ice. We show that the dielectric permittivity of proposed surficial ice-bearing PSRs is lower and has a different distribution than illuminated crater floors of the same diameter range. This difference is confirmed via polarimetric analysis. However, we find that regions with fewer or greater numbers of M3 detections do not have meaningfully different dielectric properties. The lack of correlation with M3 detections suggests the differences in radar properties are likely due to a smoother surface at the wavelength scale, perhaps as a consequence of the presence of deeper ice, as suggested by prior studies.

Abstract Surface water ice within lunar permanently shadowed regions (PSRs) could have an enhanced visible wavelength reflectance relative to lunar regolith. Moon Mineralogy Mapper (M3) infrared spectroscopic detections compose one data set previously interpreted as surface ice occurrences within the PSRs. Here we investigate the M3 water ice identifications at higher resolution with broadband visible-wavelength mosaicked images (60 m pixel scale) obtained by the ShadowCam instrument aboard the Korea Aerospace Research Institute Korea Lunar Pathfinder Orbiter. Individual M3 positive water ice detections show no radiance contrast with their surroundings. However, north polar PSRs with at least one M3 water ice detection have a ∼4.4× higher modal radiance than those lacking M3 water ice detections, although this cannot be definitively attributed to water ice. Our findings are consistent with previous estimates of ice abundance as being less than ∼30 wt%, resulting in contrast too small to be detected by the ShadowCam instrument.

ABSTRACT Observations by the Lunar Prospector and the Lunar Atmosphere and Dust Environment Explorer spacecraft suggest the existence of a near-global deposit of weakly bound water ice on the Moon, extending from a depth of a decimetre to at least three metres. The existence of such a layer is puzzling, because water ice would normally desorb at the prevailing temperatures. We here determine the conditions for long-term thermal stability of such a reservoir against solar and meteoroid-impact heating. This is done by using the highly versatile thermophysics code nimbus to model the subsurface desorption, diffusion, recondensation, and outgassing of water vapour in the porous and thermally conductive lunar interior. We find that long-term stability against solar heating requires an activation energy of $\sim 1.2\, \mathrm{eV}$ in the top metres of lunar regolith, and a global monthly night time exospheric freeze out amounting to $\sim 1$ tonne. Furthermore, we find that a lower $\sim 0.7\, \mathrm{eV}$ activation energy at depth would allow for water diffusion from large (0.1–$1\, \mathrm{km}$) depths to the surface, driven by the radiogenically imposed selenotherm. In combination with solar wind-produced water, such long-range diffusion could fully compensate for meteoroid-driven water losses. These results are significant because they offer quantitative solutions to several currently discussed problems in understanding the lunar water cycle, that could be further tested observationally.

As the NASA-led return to the Moon swings into action over the next decade via Project Artemis, this overview paper considers the prospects for a new “lunar economy” emerging from the 2030’s. If Moonbases can be established and viable resource utilisation begun, with public and privately funded research stations and lunar tourism occurring, the Moon could act as a “testbed” and an enabler for interplanetary travel beyond to Mars and then across the wider Solar System. The exploration of the Moon and its resource utilisation would focus on the availability and viability of polar water ice resources, solar power usage, hydrogen and oxygen extraction for air and fuel via In Situ Resource Utilisation (ISRU), plus research into rare minerals present in the lunar regolith and their possible extraction. The viability of helium 3 mining, possible high temperature annealing of metals and 3D printing using lunar dust is noted. With plans in place to move forward with NASA/ ESA/JAXA’s “Project Artemis” and the orbiting Gateway station, plus private initiatives making use of SpaceX’s Starship and Blue Origin’s lunar landers, cheaper access to the lunar surface will evolve. Considering the actual ownership of the Moon and lunar resources, international clarification is required – many consider that the 1967 Outer Space Treaty background needs restructuring and the gap in resource ownership and exploitation law needs new international agreement. It is considered that the lunar economy could prosper via lunar ice ISRU, possibly making use of fuel and oxygen availability for onward travel from the lunar surface, perhaps via “mass drivers” to lunar orbit. Spacecraft might then refuel initially for lunar-Earth travel. Technology development for lunar landing systems and surface habitation will enable future deep space lunar-Mars trips and eventually Mars-base settlements, with travel across the Solar System gradually evolving. Keywords: Lunar Economy, Project Artemis, Moonbases, ISRU, Lunar Ice, Space Tourism, Lunar Regolith, Lunar Observatories, Newspace, 3D Printing, Helium 3, Space Law, Lunar Gateway Station, Starship HLS, Blue Moon HLS, Lunar Mass Drivers, Mars Colonies

The lunar poles potentially contain vast quantities of water ice. The water ice is of interest due to its capability to answer scientific questions regarding the Solar System’s water reservoir and its potential as a usable space resource for the creation of a sustainable cislunar economy. The lunar polar water ice exists in extremely harsh conditions under vacuum at temperatures as low as 40 K. Therefore, finding the most effective technique for extracting this water ice is an important aspect of ascertaining the suitability of lunar water as an economically viable space resource. Based on previous work, this study investigates the impact of the different possible arrangements of icy regolith in the lunar polar environment on the suitability of microwave heating as a water extraction technique. Three arrangements of icy regolith analogues were created: permafrost, fine granular, and coarse granular. The samples were created to a mass of 40 g, using the lunar highlands simulant LHS-1, and a target water content of 5 wt. %. The samples were processed in a microwave heating unit using 250 W, 2.45 GHz microwave energy for 60 min. The quantity of water extracted was determined by measuring the sample mass change in real-time during microwave heating and the sample mass before and after heating. The permafrost, fine granular, and coarse granular samples had extraction ratios of 92 %, 83 %, and 97 %, respectively. Possible explanations for the observed variations seen in the mass loss profiles of the respective samples are provided, including explanations for the differences between samples of varying ice morphology (permafrost and granular) and the differences between samples with varying ice surface areas (fine and coarse granular). While differences were observed, microwave heating effectively extracted water in all the samples and remains an effective ISRU technique for extracting water from icy lunar regolith. Differences in the water extraction of different icy regolith could be useful in determining the arrangement of ice in buried samples.