¹E. Caminiti,²S. Besse,³A. Doressoundiram,^4,5J. Wright
Journal of Geophysical Research (Planets)(in Press) Open Access Link to Article [https://doi.org/10.1029/2025JE009359]
¹Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara, Japan
²European Space Agency (ESA), European Space Astronomy Center (ESAC), Madrid, Spain
³LIRA, Observatoire deParis, Université PSL, CNRS, Sorbone Université, Université de Paris, Meudon, France
⁴School of Physics and Astronomy, University of Leicester, Leicester, UK,
⁵School of Physical Sciences, The Open University, Milton Keynes, UK
Published by arrangement with John Wiley & Sons

NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging mission hasrevealed that about 27% of the surface of Mercury is covered by smooth plains, which are mostly volcanic inorigin. These plains are mainly located in the northern hemisphere, as well as within and around majorimpact basins. We used Mercury Atmospheric and Surface Composition Spectrometer data to perform anexhaustive spectral analysis of five major impact basins: Caloris, Rembrandt, Beethoven, Tolstoj, andRachmaninoff. We highlighted the existence of a new high‐reflectance spectral unit, that had previously onlybeen identified within the Rembrandt basin, as a major unit being more widespread. We named this new unitYoung High‐reflectance Red Plains. We found a common sequence of volcanic episodes that infilled thebasins and shaped their current surface spectral properties. We have shown that the size of the basin and theage of the volcanic infills are likely important parameters for the layering of different volcanic plains,defining the surface spectral units. Our study gives access to mantle properties, and we suggest thatheterogeneity in the mantle is certainly not necessary to explain the spectral properties of effusive volcanismassociated with impact basins. Future observations by the ESA‐JAXA‐BepiColombo mission are eagerlyawaited to better constrain the planet’s spectral, compositional, morphological, and geophysical surfaceproperties.

¹S.A.Connell et al. (>10)
Journal of Geophysical Research (Planets)(in Press) Open Access Link to Article [https://doi.org/10.1029/2025JE009243]
¹Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN, USA
Published by arrangement with John Wiley & Sons

Investigating the stability of hydrated minerals is integral for examining the preservation ofrocks for potential Mars Sample Return and has major implications for models that use rover‐basedobservations to quantify Mars’ global water budget. The Mars 2020 Perseverance rover produces abrasionpatches to investigate fresh rock surfaces at Jezero crater, Mars. However, due to operational constraints, thefull analysis process typically takes several martian days (sols), and freshly exposed hydrated minerals maydehydrate upon atmospheric exposure between abrasion patch creation and their analyses. To assess thepotential for short‐term dehydration, the SuperCam instrument conducted the first in situ rover‐based dehydration experiment on rock exposures of the “Bright Angel formation.” The SuperCam andSHERLOC rover instruments indicated that the primary mineral hydration phases were Fe‐hydroxides, Ca‐sulfates such as bassanite (mixed with anhydrite), with possible minor contributions from non‐interlayer‐waterphyllosilicates (e.g., hydroxyl‐bearing only). The experiment involved a four‐sol sequence of observations onthe Steamboat Mountain abrasion patch, beginning just 22 min after abrasion. Dehydration was assessed bytracking changes in the 1.93 μm H2O absorption feature, which is sensitive to structural, absorbed, andadsorbed water. No significant changes in hydration were observed over the 93 hr, suggesting that the exposedminerals were already in a low hydration state and/or exhibit high stability under current martian surfaceconditions. These findings imply bulk rocks with low hydration and high stability minerals may not dehydrateupon exposure to the modern martian atmosphere on short time scales, consistent with predictions fromlaboratory simulations of Mars‐like environments.

^1,2Angel Mojarro,²José C. Aponte,²Jason P. Dworkin,²Jamie E. Elsila,²Daniel P. Glavin^3,4,5, Harold C. Connolly Jr.,³Dante S. Lauretta
Proceedings of the Nstional Academy of Sciences of the USA (in Press) Open Access Link to Article [https://doi.org/10.1073/pnas.25124611]
¹National Aeronautics and Space Administration Postdoctoral Program, Oak Ridge Associated Universities, Oak Ridge, TN 37830
²Solar System Exploration Division, National Aeronautics and Space Administration, Goddard Space Flight Center, Greenbelt, MD 20771
³Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721
⁴Department of Geology, School of Earth and Environment, Rowan University, Glassboro, NJ 08028
⁵Department of Earth and Planetary Sciences, American Museum of Natural History, New York, NY 10024

NASA’s OSIRIS-REx mission characterized the asteroid Bennu and delivered pristine samples of its regolith to Earth. Coordinated analyses of this primitive, carbonaceous material are elucidating the abiotic formation and inventory of prebiotic organic compounds in the early Solar System. Using pyrolysis and wet-chemistry techniques, we analyzed aggregate (unsorted particulate) material and three distinct stones that appear to correspond to different boulder types observed by the spacecraft. Results from the aggregate were consistent with previous work that detected the five canonical nucleobases and 14 of the 20 α-amino acids utilized by life to synthesize proteins. However, our analytical approach tentatively uncovered trace signals of a fifteenth α-amino acid, tryptophan, which has not been detected previously in extraterrestrial materials. Further, we found that the distributions of insoluble and soluble-derived organics differ between distinct stones, suggesting heterogeneous geologic processing within Bennu’s parent body. The distributions of alkylated polycyclic aromatic hydrocarbons resemble those in aqueously altered carbonaceous chondrites and are consistent with an abiotic origin through aqueous reactions. Our findings expand the evidence that prebiotic organic molecules can form within primitive accreting planetary bodies and could have been delivered via impacts to the early Earth and other Solar System bodies, potentially contributing to the origins of life.

¹S.A. Crowther et al. (>10)
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2025.12.008]
Department of Earth and Environmental Sciences, The University of Manchester, UK
Copyright Elsevier

We report an I-Xe age of 7.94 ± 0.92 Myr after formation of calcium aluminium inclusions (CAI), and an iodine concentration of 67 ± 1 ppb for material returned from asteroid (162173) Ryugu by JAXA’s Hayabusa 2 mission. These were determined from multi-step laser heating xenon isotopic analysis of samples A0105-03 and A0105-12 (100 µg and 70 µg, respectively), the smaller of which had been neutron irradiated to convert 127I to 128Xe. The I-Xe age likely corresponds to the end of significant loss of volatiles from the parent body. A simple statistical model of all 24 xenon isotopic analyses of Hayabusa 2 material reported to date, including one sample that has an elevated concentration attributed to Xe-P7, suggests a bulk xenon content of 2.0–2.7 × 10−7 cm3 STP g−1 for such material. This is a factor of 12–60 times higher than suggested by analyses of CI chondrite meteorites that have been exposed to the terrestrial atmosphere.
The bulk xenon isotopic composition is enriched in the heavy isotopes (134, 136Xe) relative to Average Carbonaceous Chondrite (AVCC) xenon, consistent with loss of some planetary xenon (“Q-Xe”) during aqueous alteration allowing a greater relative contribution from presolar nanodiamonds than found in AVCC. The I-Xe age is within the range of I-Xe ages for aqueous alteration of CI material; it likely records either the closure of iodine-rich sites to xenon loss towards the end of a period of heating that was associated with aqueous alteration, or precipitation of iodine-bearing minerals driven by loss of water. We use a simple statistical model of xenon analyses of Ryugu material to investigate the concentration of xenon in CI material. The presence of the rare Xe-P7 component in one reported analysis increases the estimated gas concentration and so increases the discrepancy between xenon concentrations measured in Hayabusa2 samples and CI meteorites. This is consistent with a comparatively rare Xe-P7 carrier being susceptible to loss when exposed to the terrestrial atmosphere. We measured an iodine concentration of 67 ± 1 ppb, which is comparable to other analyses of CI chondrites by neutron-irradiation noble gas mass spectrometry (NI-NGMS). Our sample was sealed within a capillary tube during irradiation allowing us to monitor any gas lost from the sample; loss of iodine-derived 128Xe during the irradiation process cannot account for any discrepancy between our derived iodine concentration and those determined in carbonaceous chondrites by other methods.

¹Oliveira, B. H.,¹Snape, J. F.,¹Tartèse, R.,²Jeon, H.,²Whitehouse, M. J.,¹Joy, K. H.
Advances in Geochemistry and Cosmochemistry 1, 772 Open Access Link to Article [https://doi.org/10.33063/agc.v1i2.772]
¹Department of Earth and Environmental Sciences, The University of Manchester, Manchester, UK
²Department of Geosciences, The Swedish Museum of Natural History, Stockholm, Sweden

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

¹Romain Tartèse et al. (>10)
Advances in Geochemistry and Cosmochemistry 1, 776 Open Access Link to Article [https://doi.org/10.33063/agc.v1i2.776]
¹Department of Earth and Environmental Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom

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

¹Jared M. Long-Fox, ¹Humberto Campins, ¹Daniel T. Britt
Planetary and Space Science 270, 106229 Open Access Link to Article [https://doi.org/10.1016/j.pss.2025.106229]
¹University of Central Florida Department of Physics, 4111 Libra Drive Room 430, Orlando, FL, 32816, USA

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

¹J.M. Comellas et al. (>10)
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2025.116902]
¹University of Hawai‘i at Mānoa, 2500 Campus Rd, Honolulu, 96822, HI, USA
²Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, 87545, NM, USA
Copyright Elsevier

Manganese plays a crucial role as a paleo-environmental and geological indicator due to its sensitivity to redox potential and pH variations in the environment. On Earth, the association between the rise of atmospheric oxygen during the Great Oxidation Event and the presence of Mn in the sedimentary rock record underscores its significance. In this study, we reexamined ChemCam targets from the first 600 sols of the Mars Science Laboratory mission, focusing on identifying instances of above-average Mn within these targets. These elevated-Mn targets were categorized into distinct geologic classes, revealing a pattern linking heightened Mn levels with diagenetically altered materials, such as calcium sulfate veins and concretions, as well as clay minerals within the same targets, indicating a compelling relationship between Mn enrichment and diagenetic processes. High concentrations of Mn were observed in chemically altered targets, suggesting the occurrence of multiple fluid events: the first to alter the material and the second to deposit Mn. The observed patterns suggest multiple diagenetic events and redox cycling that facilitated the deposition and transport of Mn subsequent to the initial dissolution of basaltic materials. This research sheds light on the complexity of martian diagenetic processes and their implications for the planet’s environmental evolution.

^1,2,3C. J. Gimar et al. (>10)
Journal of Geophysical Research (Planets)(in Press) Open Access Link to Article [https://doi.org/10.1029/2025JE009304]
¹Department of Physics and Astronomy, Univeristy of Texas at San Antonio, San Antonio, TX, USA
²Center for Laboratory Astrophysics and Space Science Experiments (CLASSE), Space Science Division, Southwest Research Institute, San Antonio, TX, USA
³Space Science Division, Southwest Research Institute, San Antonio, TX, USA
Published by arrangement with John Wiley & Sons

Building on our previous studies of the far-ultraviolet (FUV) reflectance of Apollo soil 10084 and lunar soil simulants JSC-1A and LMS-1 (Gimar et al., 2022, https://doi.org/10.1029/2022je007508; Raut et al., 2018, https://doi.org/10.1029/2018je005567), we present new FUV results for Apollo soils 68501 and 71061. Heavily weathered soils (68501, 10084)–enriched in submicroscopic Fe, agglutinates, and sub-micron scale roughness as revealed by our electron microscopy investigations–are darker in the FUV and predominantly backscatter incident light. In contrast, the relatively less weathered subsurface 71061 soil is approximately twice as bright, exhibits forward scattering, and presents a steeper blue spectral slope between 130 and 160 nm compared to the weathered soils. Differences in either primary composition or mineralogy appear to have little to no effect on the FUV albedo or scattering behavior of these soils since the reflectance of high-Ti mare 10084 and low-Ti highland 68501 are nearly indistinguishable within error. Further investigation of additional Apollo-era soils across various maturity indices is needed to fully characterize the influence of space weathering on lunar soil FUV spectrophotometric response.

¹O. Beyssac et al. (>10)
Earth and Planetary Science Letters 675, 119746 Open Access Link to Article [https://doi.org/10.1016/j.epsl.2025.119746]
¹Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, CNRS UMR 7590, Muséum National d’Histoire Naturelle, Sorbonne Université, 75005 Paris, France
Copyright: Elsevier

Based on observation and data from meteorites and in situ scientific missions, experiments as well as models, the Martian mantle is assumed to share some compositional and mineralogical affinity with the terrestrial mantle. However, there might be subtle differences like the Martian mantle being more ferroan. Yet, we do not have any direct analysis of a Martian mantle rock to confirm this assumption. NASA’s Perseverance rover found olivine-rich boulder-sized float rocks on the upper Jezero fan (Mars). These boulders have an ultramafic composition and their mineralogy is dominantly composed of Fo73±3 olivine with high-Mg orthopyroxene, Cr-rich Ti-Fe oxides and minor plagioclase and high-Ca pyroxene. Microtextural and petrological analysis reveals that these minerals crystallized at equilibrium. In addition, these boulders are different from all the bedrocks analyzed by Perseverance along its traverse which are crustal igneous rocks and sediments. Comparing our data to Martian meteorites and available Mars bulk silicate models (BSM), we discuss that these boulders could represent primitive melts and/or lower crustal material, and we specifically hypothesize that they could be mantle peridotites. We propose that these putative mantle rocks could have been excavated by the succession of impacts from the shallow mantle or lower crust in the Isidis region where Jezero crater is located. These olivine-rich boulders could thereby constitute the first direct analysis of a Martian mantle rock.