^1,2Martin Cordiner et al. (>10)
Nature 655, 870–874 Open Access Link to Article [10.1038/s41586-026-10771-6]

¹Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, MD, USA
²Department of Physics, Catholic University of America, Washington DC, USA

We currently do not have a copyright agreement with this publisher and cannot display the abstract here

¹Haoyu Li,¹Ren T. C. Marquez,^1,2Gerrit Budde,³Haolan Tang,⁴Alexander N. Krot,⁵Marina A. Ivanova,⁶Johan Villeneuve,¹ François L. H. Tissot
Proceedings of the National Academy of Sciences 123, 29 Open Access Link to Article [10.1073/pnas.2529765123]

¹The Isotoparium, Division of Geological and Planetary Sciences, Caltech, Pasadena, CA 91125
²Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912
³National Key Laboratory of Deep Space Exploration/State Key Laboratory of Lithospheric and Environmental Coevolution, University of Science and Technology of China, Hefei 230026, China
⁴Hawaii Institute of Geophysics and Planetology, University of Hawai’i at Mānoa, Honolulu, HI 96822
⁵Vernadsky Institute of Geochemistry and Analytical Chemistry, Moscow 119991, Russia
⁶Centre de Recherches Pétrographiques et Géochimiques, CNRS, Université de Lorraine, UMR7358, Nancy F-54000, France

The 26Al-26Mg systematics in calcium–aluminum-rich inclusions (CAIs)—the oldest known Solar System solids—has traditionally been used to provide high-resolution temporal constraints on the early Solar System evolution. More recently, the study of variations in the initial Mg isotope composition has emerged as a means to probe for potential compositional heterogeneity in the nascent solar nebula. Here, we report high-precision magnesium isotope data for a collection of 19 CAIs that captures the diversity of refractory inclusions. The data reveal widespread Mg isotope heterogeneity prior to 26Al decay, covering a large range from −0.285 to +0.088‰. Combined with literature data, the distribution of Mg isotope heterogeneity in CAIs forms a continuum and no longer defines distinct populations. Our findings therefore suggest a continuous CAI formation process that captured a rapid temporal change in the composition of infalling material from the parental molecular cloud of the Solar System.

¹M. C. Benner,¹B. S. Prince,¹D. L. Schrader,¹T. J. Zega
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70212]

¹Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA
²Astromaterials Research and Exploration Science (ARES) Division, XI
³Research Office, NASA Johnson Space Center,Houston, Texas, USA3Department of Materials Science & Engineering, University of Arizona, Tucson, Arizona, USA
Published by arrangement with John Wiley & Sons

Here we report on the microstructure and chemistry of sulfide minerals returned from asteroid (162173) Ryugu. We identify a unique sulfide population in particle A0016 composed of violarite (FeNi₂S₄), pyrite (FeS₂), chalcopyrite (CuFeS₂), pyrrhotite (Fe_1-xS), and pentlandite ([Fe,Ni]₉S₈). Violarite, pyrrhotite, and pyrite reveal evidence of formation from a fluid including porosity, phyllosilicate inclusions, and gaps along grain boundaries due to volume change. Violarite grains are polycrystalline with spatially correlated Ni and Co enrichments and contain pyrrhotite lamellae measuring 100s nanometers across. Pyrite assemblages are polycrystalline with spatially anticorrelated Ni and Co enrichments. In comparison, the chalcopyrite grain is a compositionally homogeneous single crystal spatially associated with rutile (TiO₂). The data suggest that particle A0016 experienced multiple generations of fluid flow. The first generation of fluid flow occurred at low temperatures (25 to 100 °C) under alkaline (pH > 8) conditions, leading to the precipitation of pyrrhotite and pentlandite. In comparison, the second generation of fluid flow was acidic (pH < 6.5) and reducing (−0.14 ≤ Eh ≤ −0.36) at elevated temperatures (230 to 300 °C), leading to formation of pyrite, violarite, and chalcopyrite. The elevated temperatures required to produce this sulfide population are consistent with heating from an impact on Ryugu’s parent body.

¹H. T. Manelski et al. (>10)
Journal of Geophysical Research: Planets (in Press) Open Access Link to Article [https://doi.org/10.1029/2026JE009769]
¹Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN, USA
Published by arrangement with John Wiley & Sons

To meet the objectives of the many robotic and human missions planned for the Moon in the coming decade, new scientific instruments are currently under development. Laser-induced breakdown spectroscopy (LIBS) is a robust technique for quantifying elemental abundances by focusing a pulsed laser to generate a plasma and collecting its emission spectrum. LIBS is particularly well suited for lunar applications because of its ability to detect key light elements, including hydrogen, an important resource for future human exploration. LIBS mapping is an emerging approach in which dense, regularly spaced grids comprising hundreds of analysis points are acquired, rather than sparse raster measurements. This technique enables the delineation of clasts in brecciated rocks, identification of chemical zoning, and quantification of bulk chemistry over the scanned area. In this work, a comprehensive quantitative LIBS calibration was developed under vacuum using lunar-relevant geologic standards. This calibration was then applied to produce the first LIBS elemental map (6 × 6 mm using 150 micron raster spacing) of a lunar meteorite in lunar atmospheric conditions, with Laâyoune 002 as the target of the study. The derived major-element chemistry is consistent with a feldspathic breccia dominated by Ca-rich plagioclase (anorthite) with minor mafic clasts. The scanned area yields an estimated normative plagioclase abundance of 86%–89%, comparable to other feldspathic lunar meteorites thought to sample nearly pure lunar highlands material. These results demonstrate the utility of LIBS mapping for investigating sub-millimeter-scale chemical heterogeneity in lunar rocks and highlight its potential for future lunar surface missions.

¹Chunjie Cao,¹Duojun Wang,¹Kenan Han,¹Kewei Shen,¹Kexuan Zhang
Journal of Geophysical Research: Planets (in Press) Link to Article [https://doi.org/10.1029/2026JE009722]

¹High Pressure Sciences Experiment Center, College of Earth and Planetary Sciences, University of Chinese Academy ofSciences, Beijing, China
Published by arrangement with John Wiley & Sons

The vesicles of meteorite fusion crusts offer a key window into transient processes during atmospheric entry, yet their formation mechanisms remain poorly constrained. In this study, we investigated the morphology, mineralogical composition, and evolutionary mechanisms of vesicles in the fusion crust and primary lithology of the meteorite NWA 10645 using micro-CT as the primary technique, complemented by SEM–EDS petrography. Vesicle nucleation in the fusion crust was likely driven by volatile supersaturation generated from multiple reservoirs, including apatite, pyroxene, melt inclusions, and mesostasis. After nucleation triggered by apatite devolatilization, isolated vesicles continued to grow and underwent three evolutionary stages: early growth, aggregation, coalescence, and critical rupture. Micro-CT 3D imaging shows that adjacent nucleated vesicles rapidly aggregated within a short time, forming bead-like alignments, then gradually coalesced into larger pores, and evolved into ellipsoidal shapes due to inertial tensile forces generated in the melt during high-velocity atmospheric entry, while near-surface vesicles approached critical rupture. Furthermore, Classical Nucleation Theory (CNT) is applied for the first time to predict a minimum nucleation radius of 23–70 nm, significantly smaller than the vesicle sizes resolved by micro-CT and SEM. This result indicates that vesicle nucleation occurs at a transient nanoscale stage. Diffusion-length estimates further suggest that volatile transport in the melt could support subsequent vesicle growth to experimentally observable micron-scale sizes.

¹J. R. Hill,¹P. R. Christensen
Journal of Geophysical Research: Planets (in Press) Open Access Link to Article [https://doi.org/10.1029/2026JE009775]
¹School of Earth and Space Exploration, Arizona State University, Tempe, Arizona, USA
Published by arrangement with John Wiley & Sons

Martian chloride salt deposits were first identified by Osterloo et al. (2008, https://doi.org/10.1126/science.1150690) and surveyed by Osterloo et al. (2010, https://doi.org/10.1029/2010je003613) primarily using thermal infrared data acquired by the Thermal Emission Imaging System (THEMIS) onboard the 2001 Mars Odyssey spacecraft. Over the subsequent 15 years, the THEMIS instrument has greatly expanded its areal and repeat coverage of the Martian surface. A principal component-based index was also developed to identify chloride salts and quantify the confidence level of their detection. Pairing the expanded data set with this improved analytical technique enabled a more accurate global survey of chloride salts, which identified 1,605 distinct deposits covering 11,974 km2. This includes 777 newly identified deposits, which represents a ∼20% increase in the surface area (∼1,997 km2) of identified chloride salts. The chloride salt deposits are primarily associated with Noachian-aged terrains, with a significant percentage occurring in Early Noachian terrains. A steep drop-off in chloride deposit occurrence was observed at the Noachian-Hesperian boundary. This pushes the period of chloride salt formation and deposition back to the earliest periods of Martian history, when the planet more closely resembled the Earth at the same time.

^1,2Pei Ma,³Hao Zhang
Journal of Geopyhsical Research: Planets (in Press) Link to Article [https://doi.org/10.1029/2026JE009863]
¹Planetary Environmental and Astrobiological Research Laboratory, School of Atmospheric Sciences, Sun Yat‐senUniversity, Zhuhai, China
²Now at Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy ofSciences, Guiyang, China
³School of Earth Sciences and Hubei Key Laboratory of Planetary Geology and Deep SpaceExplorations, China University of Geosciences, Wuhan, China
Published by arrangement with John Wiley & Sons

Lunar-like space weathering causes spectral darkening, reddening, and the attenuation of absorption bands due to metallic iron particles. The commonly cited iron size boundary, particles smaller than 40–50 nm redden spectra, while larger ones only darken, comes mainly from measurements of silica gel powders, and does not reflect the true particle-size effects. Using rigorous Mie theory to calculate absorption efficiencies of metallic iron spheres, we find that particles smaller than 80 nm primarily induce reddening with moderate darkening across the 0.4–2.6 μ⁢m$$ wavelengths, and the Hapke and Lucey‒Riner space weathering models are equivalent in this size range. Particles larger than ∼2 μ⁢m$$ cause darkening with only minor reddening. The upper size limit for reddening is wavelength-dependent; for 0.5–2.6 μ⁢m$$ wavelengths, particles <120 nm always redden the spectrum. Accounting for the polydisperse nature of metallic iron in lunar and laboratory samples, we incorporate the size distribution into the Lucey‒Riner space weathering model and validate it with laboratory data. We also discuss UV bluing, NIR reddening, and spectral brightness induced by metallic iron particles.

^1,2S. Ottaviani,^1,3L. Folco,^1,4M. D. Suttle,⁵R. Repič,⁵L. Mancini,⁵T. Battiston,^1,6S. Iannini Lelarge,^1,3M. Masotta
Journal of Geophysical Research: Planets (in Press) Open Access Link to Article [https://doi.org/10.1029/2026JE009650]
¹Dipartimento di Scienze della Terra, Università di Pisa, Pisa, Italy
²Dipartimento di Fisica e Geologia, Università degliStudi di Perugia, Perugia, Italy
³CISUP, Centro per l’Integrazione della Strumentazione dell’Università di Pisa, Pisa, Italy
⁴School of Physical Sciences, The Open University, Milton Keynes, UK
⁵Slovenian National Building and CivilEngineering Institute ‐ ZAG, Ljubljana, Slovenia
⁶Consiglio Nazionale delle Ricerche, Istituto di Geoscienze e Georisorse,Pisa, Italy
Published by arrangement with John Wiley & Sons

We estimate the cosmic dust flux to Earth through the study of rare micrometeorites that preserve part of their precursor features during atmospheric entry heating, namely unmelted and scoriaceous subtypes. Combining high-precision mass balance measurements, X-ray computed microtomography and scanning electron microscopy, we studied mass, size and petrography of 207 micrometeorites recovered from sediment traps in the Transantarctic Mountains (TAM), ranging from ∼170 to ∼1650 µm. Chondrules were identified in ∼14% of the micrometeorites, particularly among coarse-grained and composite particles. The analysed population shows a bimodal size-frequency distribution, with peaks at ∼305 µm and ∼470 µm. A similar bimodal distribution was previously reported from the TAM cosmic spherule population, yet shifted towards lower sizes. This size-shift is consistent with an average mass loss of ∼87% during atmospheric entry heating. The mass-size relationship follows a power-law, where the spherical equivalent diameter (d_µm) and mass (m_µg) of the micrometeorite are related by: 𝑚 =1.07 ×10−6 𝑑2.96$$. The size-frequency distribution of the fine- and coarse-grained micrometeorites reveals two well-separated clusters, with peaks at ∼315 µm and ∼550 µm, respectively. These observations suggest that the bimodal distribution in the micrometeorite flux reflects contrasting lithological end-member components with different physical properties and fragmentation behaviours during dust production in space. Based on earlier mass flux estimates from TAM melted micrometeorites and accounting for the mass loss due to atmospheric entry derived here, we calculate a time-averaged pre-atmospheric mass flux of ∼12,000 (±6,000) t/yr over the Quaternary, suggesting that the influx has remained stable over the last few million years.

¹Jasmijsn Van der Graaf, ²John F. Mustard, ¹Annemiek C. Waajen, ³Frank J.A. Van Ruitenbeek, ^4,5Christopher S. Romanek, ^1,4Mónica Sánchez-Román
Icarus (in Press) Open Access Link to Article [https://doi.org/10.1016/j.icarus.2026.117262]
¹Geobiology Lab, Earth Sciences Department, Vrije Universiteit Amsterdam, De Boelelaan 1100, 1081HV Amsterdam, the Netherlands
²Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI, USA
³Department of Applied Earth Sciences, Faculty of Geo-Information Science and Earth Observation, University of Twente, Drienerlolaan 5, 7500 AE Enschede, the Netherlands
⁴NASA Astrobiology Institute, USA
⁵Department of Earth and Environmental Sciences, Furman University, Greenville, SC, USA
Copyright Elsevier

Microbial activity plays a crucial role in the precipitation of carbonate minerals, mediated by bacterial cells and their secreted extracellular polymeric substances (EPS). Traditional detection of such biosignatures often requires invasive chemical treatments. This study explores the potential of Fourier Transform Infrared (FTIR) spectroscopy as a non-destructive tool to identify compositional features and microbial imprints in mixed-cation carbonates, providing a new pathway for remote sensing applications and in situ mineralogical studies. Carbonate samples from natural settings and laboratory experiments, under both biotic and abiotic conditions were analyzed to reveal their distinct spectral characteristics. The minerals studied include dolomite, siderite, ankerite, (hydro)magnesite, and various carbonate hydroxides, with varying amounts of the cations Ca2+, Mg2+ and Fe2+.
Distinct FTIR spectral characteristics were observed: dolomites, in particular, exhibited consistent clustering in overtone band positions around 2300 nm and 2500 nm. While this clustering was less apparent in other carbonate types, Fe2+ content could be reliably traced through a unique near-infrared absorption feature, whose intensity correlated with Fe2+ abundance following a square root function.
Despite the overlap of biosignature and mineral spectral features, specific markers emerged in biogenic samples. These included weak absorptions near 3310 nm (indicative of alkene bonds) and enhanced OH− bands around 1400 nm and 2760 nm, possibly related to phenols, alcohols, or structural water-components often associated with microbial EPS. FTIR spectroscopy is sensitive to trace amounts of water and organic compounds, making it a promising tool for evaluating precipitation conditions and the diagenetic history of mixed-cation carbonates.

¹Sophie Benaroya, ¹Christopher D.K. Herd
Earth and Planetary Science Letters 691, 120176 Open Access Link to Article [https://doi.org/10.1016/j.epsl.2026.120176]
¹Department of Earth and Atmospheric Sciences, 1-26 Earth Sciences Building, University of Alberta, Edmonton, AB T6G 2E3, Canada
Copyright Elsevier

Constraining the oxygen fugacity (fO2) of the mantle of Mars is critical for understanding planetary differentiation processes and magmatic evolution. The degree to which the shergottite martian meteorites faithfully record the redox states of their mantle sources remains obscured by several factors. One of these factors is the various methods used to estimate fO2: Fe-based oxybarometers require multiple minerals to be found in chemical equilibrium, which can be challenging to obtain, while previous V-based values rely on estimated parental melt compositions. Here, we present new, mineral-specific V/Sc oxybarometers calibrated for olivine and pyroxene in shergottites using experimentally determined partition coefficients. This method obviates the need for parental melt V concentrations and allows for fO2 determination from single mineral phases, bypassing the equilibrium constraints that limit Fe-oxybarometry. We applied these calibrations to a petrologically diverse suite of geochemically depleted, intermediate, and enriched shergottites. Our results reveal that: (1) basaltic shergottites, previously estimated at fO2 ∼FMQ-1, record a significantly lower initial/magmatic fO2 of ∼FMQ-1.7; (2) the magmatic fO2 of shergottites is correlated with their geochemical enrichment; and (3) all shergottites show oxidation of a magnitude of >0.5 log units with progressive crystallization. The V/Sc oxybarometers provide a robust tool for estimating the magmatic fO2 of shergottites and tracking their redox changes throughout their petrogenetic histories.