Impact-induced high temperatures are a key driver of titanium (Ti) redistribution in Ti-bearing phases, which is crucial for understanding element cycling on the Moon. However, direct mineralogical evidence for the redistribution pathways of Ti during extreme impact processes is still lacking. In this study, we report the first discovery of metallic Ti grains preserved in Chang’e-6 lunar regolith. These grains are characterized by their microscale size, droplet morphology, native Ti composition, and polycrystalline structure. The presence of Np–Fe ^0 -bearing silicate glass inclusions within the metallic Ti indicates a lunar surface origin rather than terrestrial contamination. Our results reveal that the coexistence of metallic Ti and Np–Fe ^0 grains formed via the impact-induced vaporization of ilmenite (FeTiO _3 ), followed by Ti and Fe vapor deposition on the Moon. The discovery of lunar metallic Ti documents a novel impact-driven vapor-deposition process on the Moon. This finding also suggests that impact heating on the Moon and other airless planetary bodies is a viable mechanism for generating high-purity metallic Ti resources.

Abstract Impact-cratering is a ubiquitous geologic process on the Moon. The impact-induced mineralogical micro-structures in lunar sample can provide information about their formation conditions on the Moon. However, the interpretation of these micro-structures remains challenging due to the complex and variable nature of impact processes. In this study, a piece of impact ejecta was recognized in Chang’e-5 regolith and characterized using petrographic and geochemical techniques. Using the mineralogical texture (i.e., corona texture around olivine) in such impact ejecta, the formation conditions were constrained to T > 1300 °C, stress-free, and a cooling rate 12 °C/min. These conditions are different from those previously reported for impact-induced rocks on the Moon, which are typically buried under impact melt sheets and ejecta blankets. These results indicate that lunar impact ejecta exposed at the surface record high-temperature, rapid quenching conditions distinct from buried impact rocks. Graphical Abstract

The accretion of terrestrial planets involved violent collisions among planetesimals, but the mechanisms of volatile element loss during these impacts remain debated. Chondrites, the building blocks of planets, preserve a direct record of these processes. To investigate the behavior of volatiles during impacts, we conducted a paired study of sulfur (S) and copper (Cu) elemental abundances and isotope compositions in shock-melted and unmelted portions of three ordinary chondrites (Chelyabinsk LL5, Viñales L4, Tassédet 004 H5). Our results reveal that sulfur is highly mobile during shock metamorphism. Its migration mechanism transitions from sulfide melt injection at lower shock levels to sulfide decomposition and S2 vapor transport at higher intensities. The latter process leads to substantial S loss and pronounced heavy isotope enrichment in shock melt pockets (SMPs). In contrast, copper exhibits limited volatility, resulting in negligible Cu isotope fractionation under most shock conditions. Measurable Cu loss and heavy isotope enrichment were observed only in the most intensely shocked sample. Mass balance modeling indicates that these processes occurred under extreme shock conditions, and the observed isotope fractionation is best explained by vaporization in a diffusion-limited regime. Our findings demonstrate that impact-induced vapor loss is an effective mechanism for planetary sulfur depletion, whereas the Cu inventory of planetary bodies was likely governed by sulfide segregation during magmatic differentiation rather than evaporation during accretionary collisions.

Space weathering constantly alters airless planetary bodies (e.g., the Moon), changing the composition and texture of their surface materials. However, how space weathering alters accessory minerals on the planetary surfaces is still unclear. This study uses transmission electron microscopy to investigate the space weathering features of diverse minerals from Chang'e-5 and Chang'e-6 lunar soils. Our results show that lunar baddeleyite (ZrO2) exhibits less modification in response to space weathering, which is different from silicate minerals and ilmenite. Specifically, space weathering does not change the crystal structure and chemical composition of baddeleyite. We further reveal that bond energy and nuclear resistance are the two main factors affecting space weathering effects (particularly the formation of the amorphous layer). These results suggest that baddeleyite is a stable phase under space weathering conditions when compared with other lunar minerals. This work also provides mineralogical evidence for the existence of natural space weathering-resistant materials on the Moon.

Sedimentary rocks, such as mudstone, may have hosted habitable environments on Mars in the past and have a higher potential to preserve biomarkers. Preparing a martian mudstone simulant is critical for Mars habitability research and the search for life. In this study, a new martian mudstone simulant (MUD-1) was prepared and characterized. This simulant was produced by combining various Earth mineral phases, based on the mineralogy of mudstone found at Gale crater. Multiple properties of the MUD-1 simulant were thoroughly characterized, including its mineralogy, bulk chemistry, particle characteristics, reflectance spectra, density, hygroscopicity, and mechanical properties. These results show that the MUD-1 simulant closely resembles the mineralogy, bulk chemistry, and particle characteristics of mudstone on Mars. This work demonstrates that the MUD-1 simulant is an ideal analogue of martian mudstone and is suitable fora wide range of applications (e.g., scientific experiments, engineering tests, and ISRU) in the Tianwen-3 Mars sample return mission. (c) 2026 COSPAR. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Meteorite finds are commonly used to assess the chemical and isotopic compositions of their parent bodies. Among these, lithium (Li) isotopes in ordinary chondrites (OCs) have been applied to infer the Li abundance and isotopic characteristics of their parent bodies. However, Li is highly mobile in aqueous conditions and readily undergoes isotopic fractionation during fluid-mineral interactions. It remains uncertain whether Li isotopic compositions in meteorite finds reliably preserve their original parent-body signatures, particularly after prolonged terrestrial exposure. In this study, we investigated Li isotope behavior in Kumtag 015 (W3, L5) by conducting a series of leaching experiments. The untreated whole-rock sample yields a delta 7Li value of +6.1 parts per thousand, whereas all leachates exhibit heavier delta 7Li values, ranging from +8.4 parts per thousand to +14.8 parts per thousand, indicating the presence of weathering-related secondary components enriched in heavy Li isotopes. Combined with the petrographic observations and mass-balance results, these data suggest that the relatively heavy whole-rock delta 7Li of Kumtag 015 is mainly related to the addition of heavy-delta 7Li surficial fluids during terrestrial weathering, followed by the sequestration of Li into secondary minerals such as carbonates and Fe-(oxyhydr)oxides. This finding is consistent with prior work showing heavy delta 7Li in carbonates. We conclude that terrestrial alteration can substantially modify Li isotope compositions in meteorite finds, highlighting the need for caution when using such samples to trace pristine planetary Li inventories.

Secondary minerals on Mars, particularly iron oxides, record the oxidative evolution of the planet. However, the origin and timing of large-scale oxidation of the Martian surface remain poorly constrained. Here we investigate the aqueous alteration of fayalite-forsterite (Fa100-Fa0) olivine solid solutions under a 1-bar CO2 atmosphere at 45 °C. We show that Fe-rich olivine exhibits enhanced yet non-linear dissolution behavior relative to Mg-rich forsterite, and that weathering proceeds through two stages: an initial stage (0–3 days) characterized by rapid dissolution and cation release, followed by a prolonged stage (4–180 days) dominated by Fe(III) precipitation. Alteration products are primarily Fe-enriched, Mg-depleted amorphous silicate gels, consistent with precursors to phyllosilicate formation on Mars. Crystalline Fe(III) oxides (hematite and goethite) form exclusively in the most Fe-rich systems (Fa71 and Fa100), indicating that Fe(II) oxidation can occur through water-mediated redox pathways effectively even under anoxic CO2 atmosphere. However, the abundance of Fe oxides produced in our experiments is substantially lower than the 6–20 wt.% ferric phases observed on the Martian surface, suggesting that Fe-rich olivine weathering under CO2 alone cannot account for the global ferric inventory. Despite their limited abundance, these early-formed Fe(III) oxides may have acted as catalytic nuclei, facilitating subsequent oxidation processes involving other redox-active species. Our results suggest that the earliest ferric oxides on Mars could have formed locally within Fe-rich crustal terrains under CO2-dominated conditions, initiating spatially heterogeneous but progressively amplified oxidative evolution on early Mars.

Abstract The delivery and evolution of carbonaceous materials to airless planetary bodies remain poorly constrained. This study characterized a porous, aggregated, carbon-rich dust particle (CE6-CDP) from Chang’e-6 lunar samples. CE6-CDP yielded a mean δ13CVPDB value of − 25.92 ± 3.62‰ and exhibited significant nitrogen enrichment. Nano-infrared spectroscopy further detected N–H, C = N, and C–H bonds, indicating that the carbonaceous material within CE6-CDP shows organic-like signatures. Graphitic carbon with tangled and concentric textures within CE6-CDP exhibited a comparable δ13CVPDB value (−27.31‰) but contained low nitrogen, suggesting possible graphitization of some organic precursors. The coexistence of organic-like carbonaceous material and graphitic carbon is consistent with dust ejection during an impact involving a larger carbon-rich projectile. This study indicates that extraterrestrial carbon may constitute an important lunar carbon reservoir and contribute to the dark surfaces of Mercury and Vesta. These findings provide new insights into carbon transport and evolution across airless planetary bodies.

The degassing of solar wind-related volatiles is thought to contribute to volatile cycling on the Moon. However, it remains uncertain which lunar minerals preferentially release them. Here, we report an unusual foamy texture found only on the surface of ilmenite crystals within a Chang'e-6 (CE-6) basalt clast. The distribution and chemical composition of this texture indicates that it results from in-situ melting of the ilmenite surface rather than from an impact-induced splash melt. Considering the evidence-including the long exposure time, presence of deep-seated planar defects, open vesicles, large spherical np-Fe0 particles, and a rutile-like mineral-the foamy texture is interpreted to result from the intense release of abundant solar wind-related volatiles (e.g., H/H2, He, and OH/H2O) by an impact-induced conductive heating event. Restriction of the foamy texture to the surface of ilmenite within the CE-6 basalt clast indicates that solar wind composition, especially for H-related volatiles, are released more intensely from ilmenite than from silicate minerals such as pyroxene and plagioclase. Our findings suggest that solar wind-related volatiles released from high-Ti mature regolith likely made a greater contribution to the lunar exosphere and the lunar surface volatiles, including polar deposits, relative to those from low-Ti immature regions. This has important implications for understanding volatile cycles and future in-situ resource utilization on the Moon.

The mechanisms governing the lunar water cycle and hydrogen isotope (D/H) fractionation driven by solar wind implantation and micrometeorite impacts remain poorly understood. Here, using synergistic simulation experiments, we show that micrometeorite impacts not only enhance the formation of solar wind-derived water through impact-induced mineral damage, but also enable the formed solar wind-derived water to be partially retained within the impact melt. Micrometeorite impacts also induce significant hydrogen isotope fractionation, resulting in the preferential retention of isotopically lighter water within the melt, while leaving the residual water isotopically heavier in the region surrounding the impact area due to thermally driven escape. We estimate that H2O released from minerals can migrate across the surface and ultimately contribute 4.34 & times; 109 - 2.39 & times; 1010 kg of water ice to the polar regions within 105 years. This study elucidates the solar wind and micrometeorites impact-driven water cycle and D/H fractionation on the Moon - processes that might also occur on other airless bodies such as Mercury and asteroids, and provides crucial insights into the origin of water in the terrestrial planets.

The behavior of volatile elements during silicate evaporation and condensation is crucial for understanding planetary formation. The Hertz-Knudsen-Langmuir equation suggests that the species evaporating from silicates are theoretically the same as those condensing simultaneously. However, recent findings from Chang’E-5 (CE-5) impact glass beads have challenged this view, with the sodium (Na) and potassium (K) oxides from the glass beads evaporating and subsequently Na and K condensing as atomic species. Here, we report two Chang’E-6 (CE-6) impact glass beads of highland origin that exhibit similar geochemical features to the previously reported CE-5 mare basaltic beads. The convergence of evidence from the distinct compositional terranes of CE-5 and CE-6 demonstrates that the condensation of atomic Na and K vapor is a common process during lunar impact events, independent of the target rock composition. Thermodynamic calculations show that at temperatures exceeding 2000 K during evaporation, O2 dissociates into atomic O, which preferentially escapes from the rock-vapor produced by impact due to its lower atomic mass than Na or K under lunar low-gravity conditions. This produces an oxygen-depleted transient atmosphere that leads to the condensation of atomic Na and K, triggering a redox reaction that incorporates the alkali metals into the melt as their oxides. In contrast, Apollo volcanic glass beads formed at relatively lower temperatures (<1800 K) without O2 dissociation, so there was no atomic Na or K condensation. These results fundamentally redefine our understanding of volatile behavior during lunar impact events and provide a new framework for interpreting surface geochemical processes on airless bodies.

China's Tianwen-2 mission plans to return samples from a small, rapidly spinning Earth quasi-satellite (469219) Kamo'oalewa. Previous studies linked Kamo'oalewa to lunar composition and origin. Here, we propose another scenario. We reanalyzed the reflectance spectrum of Kamo'oalewa and obtained an absorption band center at 1.001+-0.028 um (error is 1sigma), consistent with LL chondrites. We then conducted space weathering (SW) experiments on meteorites and found that highly space-weathered LL chondrite powder (but not slab) successfully reproduced the reflectance spectrum of Kamo'oalewa. We further traced the dynamical origin of Kamo'oalewa and found that it probably originated from the v6 secular resonance, and more specifically, the Flora family. Kamo'oalewa exhibits a similar composition to Itokawa and 7 objects in the Flora family, but with a higher degree of space weathering. We, therefore, proposed that Kamo'oalewa probably originated from the Flora family and developed an Itokawa-compositional, highly space-weathered, fine-regolith-dominated surface.

Solar wind implantation is widely recognized as a primary source of hydroxyl (OH) and water on the lunar surface, yet the kinetics and controlling mechanisms of this process remain poorly constrained. Here we present proton implantation experiments on San Carlos olivine conducted at 20, 90, and 130°C to quantify the kinetics and saturation behavior of OH formation. The OH abundance increases with H+ fluence following an exponential function and approaches a temperature-dependent saturation level. The fitted saturation concentration decreases with increasing temperature, whereas the apparent rate constant increases, indicating a decoupling between reaction kinetics and OH yield. Post-implantation heating experiments demonstrate negligible OH loss, ruling out thermal instability as the cause of reduced OH abundance at elevated temperatures. Instead, we propose a temperature-dependent branching mechanism in which implanted hydrogen partitions between OH formation and H2 recombination. Higher temperatures enhance hydrogen mobility, promoting H-H recombination and suppressing OH formation efficiency. The conversion ratio of H+ to OH decreases progressively with fluence, providing a unified explanation for the large discrepancies reported in previous studies. These results provide a quantitative framework for solar wind-induced water formation and a mechanistic explanation for the latitude-dependent distribution of OH/H2O on the Moon.

Lunar regolith has undergone prolonged space weathering, primarily driven by solar wind irradiation and micrometeorite impacts, which has substantially altered the mineral’s surface properties. The extent of solar wind radiation damage on mineral surfaces varies, depending on differences in the mineral structure, composition, and exposure duration. Here, we investigated space weathering features of two FIB foils from two Chang’e-6 lunar grains, minerals including chromite, titanomagnetite, ilmenite, pyroxene, and merrillite. These minerals exhibited diverse responses to solar wind irradiation with an increasing resistance sequence: pyroxene < titanomagnetite < ilmenite < (chromite, merrillite). Through a comparative analysis of their damage characteristics, ilmenite generated a higher abundance of space weathering products (e.g., vesicles), suggesting it possesses superior resource utilization on the Moon. Furthermore, nanophase metallic iron (npFe0) formed in all iron-bearing minerals, with its particle size positively correlating with bulk iron content. In chromite, both the npFe0 particle size and vesicle increased with prolonged solar wind radiation exposure. This study enhances our understanding of space weathering in lunar minerals, providing insights relevant to the evolution of lunar regolith, while also establishing its significance for guiding the in situ utilization of lunar surface resources.

Studies of Chang'e-5 samples have indicated a high content of solar wind-derived water at middle latitudes on the lunar surface. However, the implantation-diffusion and retainment of solar wind-derived water at lunar daytime temperatures remains unclear, leaving the formation and preservation of solar wind-derived water in minerals poorly understood. Here, we conducted experiments on 1.5 keV deuterium (D) ions implanted into silicate minerals at 356 K to simulate the solar wind proton implantation at noon in the middle latitudes of the Moon. The results showed that OD formed and partial D reached several micrometers depth in the minerals after implantation, which was a result of radiation-enhanced diffusion. The diffusion coefficient was estimated to be 10(-11)-10(-12) cm(2) s(-1) and was affected by the implantation fluence, temperature, and mineral crystal structure. This study provides insights into the distribution of water on the lunar surface by investigating the formation and diffusion of solar wind-derived water preserved in different minerals at elevated temperatures.

Phosphate minerals enriched in rare-earth elements (REEs) represent one of the typical mineral phases on the Moon. Nevertheless, their space weathering behavior remains insufficiently understood. In this study, two types of REE-enriched phosphate minerals—changesite-(Y) and monazite—were identified in the Chang’e-6 lunar soil sample, which was collected from the Apollo Basin on the lunar far side, a region characterized by low REE abundance. Their potential formation mechanisms are postulated as follows: (1) they originated as exogenous materials delivered as impact ejecta from thorium-enriched source regions within the South Pole-Aitken (SPA) basin; (2) they are products of crystallization during the late-stage solidification of the lunar magma ocean. Furthermore, the two phosphate phases exhibit contrasting records of solar wind radiation damage. Abundant radiation damage tracks are observed in changesite-(Y), whereas no such tracks are present in coexisting monazite or apatite, reflecting differential thermal histories at the microscale. These findings contribute to a better understanding of material transport and mixing processes within the SPA basin, reveal microscale heterogeneity in space weathering, and have implications for future in situ resource utilization on the Moon.

China's ongoing Tianwen-2 mission will return samples from a small, rapidly spinning Earth quasi-satellite (469219) Kamo'oalewa. Previous studies linked Kamo'oalewa to lunar composition and origin. Here, we propose another scenario. We reanalyze the reflectance spectrum of Kamo'oalewa and obtain an absorption band center at 1.001 ± 0.028 μm (error is 1σ), consistent with LL chondrites. We then conduct space weathering experiments on meteorites and find that highly space-weathered LL chondrite powder (but not slab) successfully reproduces the reflectance spectrum of Kamo'oalewa. We further trace the dynamical origin of Kamo'oalewa and find that it probably originated from the ν6 secular resonance, and more specifically, the Flora family. Kamo'oalewa exhibits a similar composition to Itokawa and 7 objects in the Flora family, but with a higher degree of space weathering. We, therefore, propose that Kamo'oalewa probably originated from the Flora family and developed an Itokawa-compositional, more space-weathered, fine-regolith-dominated surface.

Abstract Hypervelocity impacts from micrometeorites or asteroids are a dominant long‐term geological process that modifies the mineralogical and elemental components of surface regolith on the Moon and other airless planetary bodies. However, the pathways by which impacts drive elemental redistribution on the Moon remain poorly understood. Here, we report the discovery of thousands of chromite (FeCr 2 O 4 ) nanoparticles deposited on a space‐weathered olivine fragment from Chang'e−5 lunar regolith. These chromite nanoparticles display morphological and textural characteristics consistent with vapor‐phase condensation rather than magmatic crystallization. We therefore propose that the deposited chromite nanoparticles formed via localized vaporization of Cr, Fe, and O from lunar regolith during hypervelocity impacts, followed by rapid condensation and deposition. This study provides direct mineralogical evidence for impact‐driven Cr‐Fe‐O vaporization and deposition, offering new insights into the elemental cycling and regolith evolution on the Moon and other airless bodies.

Thorium-rich (Th-rich) geological units have been detected by remote sensing in the Martian crust. However, there is still a lack of mineralogical evidence to constrain the magmatic processes responsible for these anomalies. In this study, we report the first discovery of thorite (ThSiO4) grains within a zircon fragment from Martian regolith breccia meteorite NWA 11220. These zircon-hosted thorite grains are micron-sized (<5 mu m) individual particles and are associated with magnetite and ilmenite inclusions. Transmission Electron Microscopy analysis shows that the thorite and zircon have become metamict due to radioactive decay, whereas magnetite and ilmenite remain crystalline. This metamict thorite provides mineralogical evidence for a highly evolved, Th-saturated, and oxidized magmatism on Mars. Furthermore, our findings offer a critical ground-truth for orbital Th anomalies and provide new insights into thorium reservoirs in the Martian crust.