^1,2,3A. I. Sheen,¹C. D. K. Herd,^2,3K. T. Tait
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70002]
¹Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada
²Department of Natural History, Royal Ontario Museum, Toronto, Ontario, Canada
³Department of Earth Sciences, University of Toronto, Toronto, Ontario, Canada
Published by arrangement with John Wiley & Sons

Accurate dating of Martian meteorites is crucial for understanding key events in the planet’s evolution. However, not all Martian meteorites are amenable to dating techniques currently in use for these rocks. The priority of sample preservation precludes mineral separation methods for low-volume specimens, whereas the less destructive in situ SIMS U-Pb method depends on the availability of U-bearing accessory minerals. Micromilling allows for spatially guided sampling of target phases down to the sub-mm scale, therefore enabling chromatography-based analysis while preserving the overall specimen. This study presents an evaluation of micromill sampling for extracting individual mineral fractions in situ from shergottites, the most common group of Martian meteorites, for Rb-Sr and Sm-Nd geochronology. Based on trace element content in major minerals in shergottites (pyroxene, plagioclase, olivine, and merrillite) and assuming that a minimum load size of 0.25 ng Sr and 1 ng Nd is required to achieve baseline isotopic precision (2σ of ~240 ppm on 87Sr/86Sr and ~100 ppm on 143Nd/144Nd), the minimum required sample volume ranges in the orders of 105–107 μm3 for one Sr isotopic analysis and 105–109 μm3 for one Nd isotopic analysis. Considering the need for sample purity, significant limitations exist in the maximum sampling resolution of the micromill instrument (~40 μm for the conical carbide drill bit chosen for this study) with respect to shergottite petrography. Insufficient grain size, irregular morphology, and the presence of small inclusions may reduce the area that can be drilled per grain. Shock-induced fractures, which sometimes act as pathways for terrestrial alteration, are pervasive in shergottites and create additional challenges for effective high-purity sampling of the target phase. In addition, variation in trace element content in the target phases may result in the realistically required drilling volumes being orders of magnitude greater than the minimum estimates. Lastly, estimated drilling time per fraction may reach over 5 h for pyroxene (Sr, Nd), plagioclase (Nd), and olivine (Sr, Nd), increasing the susceptibility to a larger procedural blank as well as requiring constant, labor-intensive monitoring for long durations. Based on these technical and physical constraints, we do not consider micromill sampling to be currently compatible with Sr isotopic analysis of olivine and Nd isotopic analysis of pyroxene, plagioclase, and olivine in shergottites. The feasibility of geochronology applications may be improved with future advances in analytical development, such as increasing the micromill sampling resolution and reducing the load size required for isotopic analysis.

¹Libby D. Tunney,²Aaron B. Regberg,¹Christopher D. K. Herd,³Richard E. Davis,⁴Christian L. Castro
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.70008]
¹Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada
²Astromaterials Research and Exploration Science Division, NASA Johnson Space Center, Houston, Texas, USA
³Texas State University, NASA Johnson Space Center, Houston, Texas, USA
⁴JES Tech, NASA Johnson Space Center, Houston, Texas, USA
Published by arrangement with John Wiley & Sons

Meteorites are easily contaminated at the Earth’s surface by microbial activity. Here, DNA extracts from two meteorite specimens and samples from curation laboratory surfaces are analyzed with amplicon sequencing, to understand microbial communities that contaminate meteorites and that may be resident in curation facilities. In addition, two different DNA extraction kits, the PowerSoil DNA Isolation Kit and the QIAamp UCP Pathogen Mini Kit, are utilized to determine if certain kits are more favorable for low biomass studies of meteorites. We find that, regardless of the type of kit used, the majority of microbial taxa that dominate meteorite and meteorite curation environments include those that are prevalent in soils or in the human microbiome. Our results have implications for advanced curation methods to protect the intrinsic properties of meteorites, such as extraterrestrial organics and minerals, from microbes. Preserving meteorites in pristine states and understanding the complex relationship between meteorites and terrestrial microbes can inform our search for the origin of life or life elsewhere in the universe.

¹Philip R. Christensen,²Victoria E. Hamilton,¹Saadat Anwar,¹Greg Mehall,²John R. Spencer,³Jessica M. Sunshine,²Harold F. Levison
Journal of Geophysical Research (Planets) Open Access Link to Article [https://doi.org/10.1029/2024JE008493]
¹School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
²Southwest Research Institute, Boulder, CO, USA
³University of Maryland, College Park, MD, USA
Published by arrangement with John Wiley & Sons

The Lucy Thermal Emission Spectrometer (L’TES) instrument acquired hyperspectral thermal infrared (TIR) observations of the Earth’s Moon during Lucy’s 2022 Earth gravity assist. L’TES covers the spectral range of 100–1,750 cm−1 (100–5.8 μm) at a spectral sampling of 8.64 cm−1 (Christensen et al., 2023, https://doi.org/10.1007/s11214-023-01029-y). The field of view (FOV) is 7.3-mrad, giving a spatial resolution on the Moon of 1,650 km. Seventeen high-quality spectra of the warm disk were acquired of Oceanus Procellarum that provide the first well-calibrated TIR observations of the Moon with high spectral resolution. The lunar surface emissivity was determined by modeling the surface radiance using two different methods that gave nearly identical results. The L’TES spectra have Christiansen feature (CF) maxima at 1,226 cm−1 (8.15 μm), a spectral band depth of ∼0.04, and a downward slope at wavenumbers >1,200 cm−1 that is characteristic of <100 μm particles. Comparison with Diviner 3-point spectral data (Greenhagen et al., 2010, https://doi.org/10.1126/science.1192196) shows excellent agreement in the CF location and band shape. The L’TES spectra closely match several lunar soil laboratory spectra (Donaldson-Hanna et al., 2017, https://doi.org/10.1016/j.icarus.2016.05.034), providing excellent ground truth for the L’TES observations, validating the L’TES data processing, and demonstrating that high-spatial and spectral resolution TIR data would provide a powerful tool for remote compositional mapping. The L’TES nightside observations accurately derived surface temperatures at 110 K, even when the Moon only filled 10% of the FOV, confirming that L’TES will accurately determine the cold Trojan asteroid temperatures.

¹Edwin S. Kite,²Benjamin M. Tutolo,¹Madison L. Turner,³Heather B. Franz,³David G. Burtt,⁴Thomas F. Bristow,⁵Woodward W. Fischer,⁶Ralph E. Milliken,⁷Abigail A. Fraeman,¹Daniel Y. Zhou
Nature 643, 60-66. Open Access Link to Article [DOI https://doi.org/10.1038/s41586-025-09161-1]
¹University of Chicago, Chicago, IL, USA
²University of Calgary, Calgary, Alberta, Canada
³NASA Goddard Space Flight Center, Greenbelt, MD, USA
⁴NASA Ames Research Center, Moffett Field, CA, USA
⁵California Institute of Technology, Pasadena, CA, USA
⁶Brown University, Providence, RI, USA
⁷Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA

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

¹Lang Zhang, ¹Ai-Cheng Zhang, ¹Xiao-Wen Liu, ²Yan-Jun Guo, ¹Jia-Ni Chen, ³Yuan-Yun Wen, ⁴Qiu-Li Li, ⁴Yu Liu, ⁴Xiao-Xiao Ling, ⁵Jin S. Zhang
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.06.032]
¹State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
²CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, China
³Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
⁴State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
⁵Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA
Copyright Elsevier

Mineralogical records of strong shock metamorphism (around or above 20 GPa) are common in L-group chondrites, Martian meteorites, and lunar meteorites, but rarely reported in Howardite-Eucrite-Diogenite (HED) meteorites. Here, we report detailed mineralogical observations of shock-induced features and ion-microprobe merrillite U-Pb ages from the pigeonite cumulate eucrite Northwest Africa (NWA) 8326. Shock-induced mineralogical features in NWA 8326 contain: (i) planar fractures in pyroxene and partial maskelynitization of plagioclase; (ii) presence of high-pressure minerals such as tissintite, stishovite, vacancy-rich augite, super-silicic garnets within melt veins, and xieite, tuite, and reidite in the host rock outside melt veins. We also observed fine-grained clinoenstatite and pigeonite at the edges of shock melt and propose they formed through metastable crystallization. Our study indicates that NWA 8326 experienced shock metamorphism of at least 20 GPa, comparable to those observed in L-group chondrites, Martian meteorites, and lunar meteorites. We propose that the relatively low shock pressures inferred for shocked eucrites in previous investigations could be due to the absence of suitable high-pressure mineralogical indicators. The ion-microprobe 207Pb/206Pb age of merrillite in NWA 8326 is 4238 ± 32 Ma (95 % confidence) and represents the timing of the shock metamorphism. The similarity of the impact ages across NWA 8326, some eucrites, lunar samples/meteorites, and chondrites suggests that there were probably widespread impact events at ∼4.2 Ga in the Solar System.

¹Fabio Joseph,²Igor Drozdovsky,^1,3Malte Junge,¹Joanna Brau,^1,3Melanie Kaliwoda
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14381]
¹Department of Earth and Environmental Sciences, Ludwig-Maximilians-University, Munich, Germany
²Directorate of Human and Robotics Exploration, European Astronaut Centre (EAC)—European Space Agency (ESA), Troisdorf, Germany
³Mineralogical State Collection, SNSB, Bavarian State Collections of Natural History, Munich, Germany
Published by arrangement with John Wiley & Sons

Chondrules are one of the oldest objects in our solar system. Therefore, they play an important role as messengers, offering new insights into the early stage of the solar system processes and potential understanding of formation. Therefore, the investigation of all detailed structures, especially not well-known inversely zoned chondrules (IZ chondrules), is crucial. In this paper, we describe the chemical as well as the structural composition of inversely zoned chondrules with EDX, light microscopy, BSE, and Raman spectroscopy, which reveal a new process in the early solar system. Inversely zoned chondrules consist of a pyroxene core surrounded by an olivine rim. The olivines have a higher Fe content (Fa, 39%–41%) compared to those found in most other chondrules. The core displays a radial pyroxene chondrule with sometimes olivines (Fa34). These IZ chondrules have originated during the early stages of our solar system and do not show the typical known forming process of chondrules. Minor fluctuations in the SiO₂ content of chondritic melts can lead to SiO₂ depletion of the residual melt at a constant temperature due to crystallization of pyroxene, which shifts the phase equilibrium in favor of fayalite-enriched olivine, which forms a rim.

^1,2Nandita Kumari, ¹John Mustard, ³Timothy D. Glotch
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2025.116721]
¹Department of Earth, Environmental and Planetary Sciences, Brown University, USA
²Planetary Science Institute, USA
³Department of Geosciences, Stony Brook University, USA
Copyright Elsevier

Visible/near-infrared (VNIR) and thermal infrared (TIR) spectroscopy have been widely used to detect and characterize the abundances of silicates across the solar system. Recently, intermediate infrared (IMIR) reflectance spectroscopy (~4 – 6 μm) has been proposed as a tool to quantify the Mg# in olivine and pyroxene with varying iron, magnesium and calcium content. The lunar surface is composed of rocks with mixed particle sizes and thus quantifying the effects of particle size is extremely important to increase the robustness of IMIR spectroscopy as a tool for lunar surface exploration. Similarly, space weathering has been known to cause optical darkening and affect the spectra of the lunar surface materials across a broad wavelength range. In this study, we have identified the emission features of lunar analog minerals/rocks and their variations with changes in particle sizes and albedo at IMIR wavelengths in simulated lunar environment (SLE). We find that the lunar analog minerals display an increase in emissivity and striking decrease in feature contrast with an increase in particle sizes or decrease in albedo. This study shows that while this wavelength range works well in reflectance space for sample characterization, using it for emissivity measurements via orbital remote sensing or in-situ rovers requires extensive study.

^1,2Tomoko Arai, ¹Takayuki Tomiyama, ²Takafumi Niihara, ³Tatsunori Yokoyama, ⁴Miwa Yoshitake, ^2,3Hiroshi Kaiden, ^2,3Keiji Misawa, ⁴Anthony J. Irving
Icarus (in Press) Open Access Link to Article [https://doi.org/10.1016/j.icarus.2025.116715]
¹Planetary Exploration Research Center, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
²National Institute of Polar Research, 10-3 Midoricho, Tachikawa, Tokyo 190-8518, Japan
³Graduate Institute for Advanced Studies, SOKENDAI, 10-3 Midoricho, Tachikawa, Tokyo 190-8518, Japan
⁴Department of Earth & Space Sciences, University of Washington, Seattle, WA 98195, USA
Copyright Elsevier

A lunar meteorite Northwest Africa (NWA) 4485 is a KREEP (potassium, rare earth elements and phosphorus)-rich polymict breccia, likely paired with NWA 4472. NWA 4485 includes mm-sized lithic clasts with variable textures and modal abundances. The lithic clasts share features with KREEP basalts, and consist dominantly of moderately Mg-rich pyroxene and less calcic plagioclase than those in the Apollo 17 KREEPy basalt with zircon and phosphates. Uranium‑thorium‑lead isotopic studies on zircon and baddeleyite in the lithic clasts and matrix of NWA 4485 revealed that the 207Pbsingle bond206Pb age spectrum (4350–3920 Ma) is compatible with that for apatite in the paired NWA 4472, broadly covering the ages of zircons in Apollo polymict breccia samples from multiple landing sites. The presence of a 4160 Ma zircon in a millimeter-sized lithic clast, a core of 4210 Ma in a detrital zircon with multiple rims of ~3960 Ma, and an individual zircon grain of 4350 Ma in the matrix clearly indicates that they are products of pre-mare multiple KREEP-related magmatism, predating the lunar cataclysm (~3900–4000 Ma).

¹S.A. Singerling, ¹F.E. Brenker, ¹B. Tkalcec, ²S.S. Russell, ³T.J. Zega, ⁴T.J. McCoy, ^3,4,5H.C. Connolly Jr., ³¹D.S. Lauretta
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2025.06.028]
¹Schwiete Cosmochemistry Laboratory, Goethe University, Frankfurt, Germany
²Planetary Materials Group, Natural History Museum, London, UK
³Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
⁴Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
⁵Department of Geology, Rowan University, Glassboro, NJ, USA
⁶Department of Earth and Planetary Sciences, American Museum of Natural History, New York, NY, USA
Copyright Elsevier

We describe nanoscale observations obtained via transmission electron microscopy of Na,Ca carbonates in OSIRIS-REx samples of asteroid Bennu. Four Na,Ca carbonate grains were observed (including the one briefly described in McCoy and Russell et al., 2025), ranging in size from 140 nm to 2.36 µm. The stoichiometry of the grains and electron diffraction data best match gaylussite (Na2Ca(CO3)2·5H2O) or pirssonite (Na2Ca(CO3)2·2H2O). The grains rapidly amorphized under the electron beam. We also found that the grains are reactive to the terrestrial atmosphere, with their compositions and textures changing over six months of storage in a standard desiccator. NaCl salts grew on the exteriors of the grains, and the compositions of the carbonates became richer in C, F, Cl, and Ca and poorer in O and Na
Neither gaylussite nor pirssonite have been observed in planetary materials other than samples from Bennu. On Earth, these phases occur in evaporites or shales from alkali lakes and, less commonly, as veins in alkaline igneous rocks. Thermodynamic modeling has shown that both phases require a low-temperature (<55 °C), Na-rich (>140 g/kg Na2CO3) brine, and their presence in the Bennu samples supports a model of salt formation on the parent body during syndepositional back-reaction of a briny fluid (McCoy and Russell et al., 2025). We argue that these minerals have not been previously observed owing either to their rare formation conditions or their susceptibility to degradation from sample preparation and analysis (e.g., electron/ion beam imaging), terrestrial weathering, and/or storage in a terrestrial environment. This study highlights the importance of collecting and carefully preserving pristine samples from planetary bodies.

¹Marina A. Ivanova,¹Svetlana N. Teplyakova,¹Cyril A. Lorenz,²Shuying Yang,²Munir Humayun
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.70005]
¹Vernadsky Institute of Geochemistry and Analytical Chemistry, Moscow, Russia
²National High Magnetic Field Laboratory and Department of Earth, Ocean & Atmospheric Science, Florida State University, Tallahassee, Florida, USA
Published by arrangement with John Wiley & Sons

Sierra Gorda 013 (SG 013) is an unusual CBa-like chondrite containing two texturally different, isotopically identical lithologies—chondritic (L1) and achondritic (L2), which should have a common origin. The metal globules of the L1 metal preserved the magmatic pattern of the siderophile element distribution that indicates they had a fractionated precursor. In this work, the trace element metal composition of lithology 2 was studied, and the revisited LA-ICP-MS data on the L1 metal was presented. Lithologies 1 and 2 have Ni and Co in the range of CB chondrites. The Ni-Co distribution in L1 and depletion in Cr of both lithologies with a negative Cr-Ni correlation are similar to that of the magmatic irons. Highly refractory siderophile element (HRSE) (W, Re, Os, Ir, Pt, Ru, Rh, and Mo) compositions of the L1 metal are highly fractionated relative to CI, but the L2 metal has a nearly uniform HRSE distribution similar to the depleted patterns of some HRSE-poor L1 metal compositions. Metal from both lithologies is depleted in volatile siderophile elements. In the L1 metal globules, the metal composition shows definite linear correlations of the HRSE elements versus Ni similar to those observed in many magmatic iron meteorites, distinct from those of the CH/CBb-zoned metal. Meanwhile, the L2 metal compositions are systematically plotted as limited clusters in the middle of the L1 trends. Based on a fractional crystallization (FC) model of the CR-like metal composition, it was shown that the distribution of siderophile elements in the metal globules of L1 can cover the full range of the fractional crystallization products of a metallic (Fe-Ni-S) liquid from the core of a differentiated body at S content 13 wt%. In contrast, the metal from L2 corresponds to a more limited range of fractional crystallization products and indicates a mixture of the fractionated metal with the primitive metal from the chondritic colliding body. Our results suggest that during a catastrophic impact event when the metallic core of a differentiated body was disrupted, the L1 lithology was quickly cooled in the impact plume, more reduced than that of CB chondrites and avoided equilibration with plume gas and preserved its fractionated HRSE patterns. The distribution of siderophile volatile elements and Au was likely overprinted by high-temperature processes of volatilization and recondensation to different degrees in the impact plume under disequilibrium conditions. The L2 metal probably avoided equilibration with the plume gas and was affected by thermal metamorphism up to 900°C in the SG 013 parent body, which possibly resulted in the higher W abundance compared to the L1 metal with a magmatic Ir-W trend due to the redox reactions with silicates under reducing conditions.