^1,2Mélissa Martinot,¹Kerri L. Donaldson Hanna,³Benjamin T. Greenhagen,¹Luis Santori,³Patrick N. Peplowski,³Joshua T. S. Cahill
The Planetary Science Journal 6, 20 Open Access Link to Article [DOI 10.3847/PSJ/ad94f0]
¹Department of Physics, University of Central Florida, 4111 Libra Drive, Orlando, FL 32816, USA
²CRPG, CNRS/Université de Lorraine, Vandœuvre-lès-Nancy, France
³The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA

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¹Peter Wurz,¹Noah Jäggi,¹André Galli,¹Audrey Vorburger,²Deborah Domingue,³Paul S. Szabo,⁴Johannes Benkhoff,⁵Océane Barraud,⁶Daniel Wolf Savin
The Planetary Science Journal 6, 24 Open Access Link to Article [DOI 10.3847/PSJ/ad95fa]
¹Space Science and Planetology, Physics Institute, University of Bern, Bern, Switzerland
²Planetary Science Institute, Tucson, AZ, USA
³Space Sciences Laboratory, University of California, Berkeley, CA, USA
⁴ESA/ESTEC, Noordwijk, The Netherlands
⁵German Aerospace Center (DLR)—Institute of Planetary Research, 12489 Berlin, Germany
⁶Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA

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^1,2Jean Charlier,¹Alice Aléon-Toppani,¹Rosario Brunetto,²Jérôme Aléon,³Ferenc Borondics
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14314]
¹Institut d’Astrophysique Spatiale, CNRS, Université Paris-Saclay, Orsay, France
²Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, Museum National d’Histoire Naturelle, CNRS UMR 7590, IRD, Paris, France
³SOLEIL Synchrotron, L’Orme des Merisiers, RD 128, Saint Aubin, France
Published by arrangement with John Wiley & Sons

Refractory inclusions (RIs) in chondrites are widely used as tracers of early solar system formation conditions. In the context of sample-return missions, a non-destructive and non-invasive analytical tool that can rapidly detect and characterize RIs in space samples during their early phase of study is highly needed. Here, we performed mid-infrared (MIR) fine-scale hyperspectral imaging over large fields of view to detect RIs in CM and CO chondrites. A database of MIR spectra of typical RIs minerals was built (1) to support future remote sensing observations in astronomical environments and (2) to develop a detection method based on machine-learning algorithms and spectral distance between sample and reference minerals. With this method, up to 96.5% of the RI content is detected in a meteorite section. Further comparison between scanning electron microscopy and spot analysis acquired in reflectance in the full MIR range shows that RIs can be classified following their mineralogy based on infrared (IR) properties. Finally, we show that the relative OH content of several RIs in CM chondrites determined from IR spectroscopy can be used to infer the extent of modification caused by aqueous alteration on the asteroidal parent body.

^1,2,3Juliane Gross et al. (>10)
Journal of Geophysical Research (Planets)(in Print) Link to Article [https://doi.org/10.1029/2024JE008585]
¹Astromaterials Acquisition and Curation Office, NASA Johnson Space Center, Houston, TX, USA
²Lunar and Planetary Institute, Houston, TX, USA
³Department Earth and Planetary Sciences, The American Museum of Natural History, New York, NY, USA
Published by arrangement with John Wiley & Sons

During the six Apollo missions, astronauts collected 2196 lunar samples, nearly all of which have been studied over the past five decades. Six Apollo samples remained unexamined until 2019 and were saved to be analyzed by the next generation of lunar scientists using advanced modern laboratory facilities. Now more than 50 years after Apollo, NASA is returning to the Moon with Artemis and will return geologic samples from a different region of the lunar surface than Apollo. Curation will play an instrumental role in helping to prepare for the safe return of these valuable samples, ensuring their integrity during all stages of the missions, and thus maximizing their scientific return. To prepare for the return of these samples, NASA initiated the Apollo Next Generation Sample Analysis (ANGSA) Program to open previously unstudied samples including unopened double drive tube 73002 and 73001 (also vacuum-sealed) from the Apollo 17 mission to the Taurus-Littrow Valley. The ANGSA program was designed to function as a low-cost analog sample return mission and served as a testing ground to understand processes, update techniques, and prepare for the preliminary examination (PE) of the to-be-returned lunar samples with Artemis. New and advanced curation techniques were developed and applied to support the analyses of 73002/73001 during the PE. Furthermore, cutting-edge analytical instruments such as X-ray Computed Tomography were utilized to aid in PE that were unavailable during Apollo. These efforts are equipping the Artemis generation for future lunar missions and lessons learned from the PE of ANGSA samples will be directly applied to Artemis.

^1,2Kun Wang et al. (>10)
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2025.01.043]
¹McDonnell Center for the Space Sciences, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, USA
²Department of Earth, Environmental, and Planetary Sciences, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, USA
Copyright Elsevier

Space weathering has long been known to alter the chemical and physical properties of the surfaces of airless bodies such as the Moon. The isotopic compositions of moderately volatile elements in lunar regolith samples could serve as sensitive tracers for assessing the intensity and duration of space weathering. In this study, we develop a new quantitative tool to study space weathering and constrain surface exposure ages based on potassium isotopic compositions of lunar soils. We first report the K isotopic compositions of 13 bulk lunar soils and 20 interval soil samples from the Apollo 15 deep drill core (15004 – 15006). We observe significant K isotope fractionation in these lunar soil samples, ranging from 0.00 ‰ to + 11.77 ‰, compared to the bulk silicate Moon (–0.07 ± 0.09 ‰). Additionally, a strong correlation between soil maturity (Is/FeO) and K isotope fractionation is identified for the first time, consistent with other isotope systems of moderately volatile elements such as S, Cu, Zn, Se, and Cd. Subsequently, we conduct numerical modeling to better constrain the processes of volatile element depletion and isotope fractionation on the Moon and calculate a new K Isotope Model Exposure Age (KIMEA) through this model. We demonstrate that this KIMEA is most sensitive to samples with an exposure age lower than 1,000 Ma and becomes less effective for older samples. This novel K isotope tool can be utilized to evaluate the surface exposure ages of regolith samples on the Moon and potentially on other airless bodies if calibrated using other methods (e.g., cosmogenic noble gases) or experimental data.

¹B. Bultel,²M. Wieczorek,³Anna Mittelholz,^4,5Catherine L. Johnson,⁶Jérôme Gattacceca,^7,8,9Valentin Fortier,¹⁰Benoit Langlais
Journal of Geophyisical Research (Planets) Open Access Link to Article [https://doi.org/10.1029/2023JE008111]
¹GEOPS, Université Paris-Saclay, CNRS, Orsay, France
²Institut de Physique du Globe de Paris, Université Paris Cité, CNRS, Paris, France
³Department of Earth and Planetary Sciences, ETH Zurich, Zurich, Switzerland
⁴University of British Columbia, Vancouver, BC, Canada
⁵Planetary Science Institute, Tucson, AZ, USA
⁶Aix-Marseille Univ, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France
⁷Université Catholique de Louvain-la-Neuve, Earth and Life Institute, Louvain-la-Neuve, Belgium
⁸Laboratoire G-Time, Université Libre de Bruxelles, Bruxelles, Belgium
⁹Géosciences Montpellier, CNRS, Univ. Montpellier, Montpellier, France
¹⁰ de Planétologie et Géosciences UMR 6112, Nantes Université, Univ Angers, Le Mans Université, CNRS, Nantes, France
Published by arrangement with John Wiley & Sons

Strong magnetic fields have been measured from orbit around Mars over parts of the ancient southern highlands crust and on the surface at the InSight landing site. The geological processes that are responsible for generating strong magnetization within the crust remain poorly understood. One possibility is that intense aqueous alteration of crustal materials, through the process of serpentinization, could have produced magnetite that was magnetized in the presence of a global core-generated magnetic field. Here, we test this idea with geophysical and geochemical models. We first determine the magnetizations required to account for the observed magnetic field strengths and then estimate the amount of magnetite necessary to account for these magnetizations. For the strongest orbital magnetic field strengths, about 7 wt% magnetite is required if the magnetic layer is 10 km thick. For the surface field strength observed at the InSight landing site, 0.4–1.1 wt% magnetite is required if the magnetic layer corresponds to one or more of the three crustal layers observed in the InSight seismic data (with thicknesses from 8 to 39 km). We then investigate the minerals that are produced by aqueous alteration for various possible crustal compositions and water-to-rock ratios using a thermodynamic model. Magnetite abundances up to 6 wt% can be generated for dunitic compositions that could account for the strongest magnetic anomalies. For more representative basaltic starting compositions, however, more than 0.4 wt% can only be generated when using high water-to-rock ratios, which could account for the weaker magnetizations beneath the InSight landing site.

¹J. N. Levin,¹A. J. Evans,²J. C. Andrews-Hanna,¹I. J. Daubar
Journal of Geophysical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2024JE008418]
¹Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI, USA
²Lunar and Planetary Laboratory, The University of Arizona, 1629 E University Blvd Tucson AZ, Tucson, AZ, USA
Published by arrangement with John Wiley & Sons

The distribution of KREEP—potassium (K), rare earth elements (REE), and phosphorus (P)—in the lunar crust is an important clue to deciphering the geochemical and thermal evolution of the Moon. Surface measurements of thorium abundance taken by the Lunar Prospector Gamma Ray Spectrometer (LP GRS) instrument have shown that KREEP is concentrated on the lunar nearside surface, mirroring the hemispheric asymmetry observed in the distribution of maria, crustal thickness, and topography. However, the overall lateral and vertical distribution of KREEP within the crust is poorly constrained, leaving uncertainty in estimates of bulk crustal thorium abundance and in the history and evolution of KREEP. In this study, we compared the overall lateral and vertical distribution of lunar KREEP in the upper crust by determining the thorium abundance of material excavated by complex impact craters. We find that the distribution of KREEP on the nearside is consistent with a layer of high-Thorium ejecta from the Imbrium impact mixing with underlying low-Th (<1 ppm) crustal material, suggesting the excavation of a sub-crustal KREEP reservoir with thorium abundances as high as 45–120 ppm by the Imbrium-forming impact. Imbrium ejecta alone does not explain the distribution of thorium on the lunar farside, particularly around the South Pole Aitken basin, suggesting other sources for farside thorium enrichments. Furthermore, our results refute the existence of a large-scale Thorium-enriched layer in the upper 16 km of the farside crust.

¹T.J.McCoy et al. (>10)
Nature 637, 1072-1077 Open Access Link to Article [DOI https://doi.org/10.1038/s41586-024-08495-6]
¹Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA

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¹D. S. Burnett et al. (>10)
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14313]
¹Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA
Published by arrangement with John Wiley & Sons

Solar wind Fe and Mg fluences (atoms/cm2) were measured from Genesis collectors. Fe and Mg have similar first ionization potentials and solar wind Fe/Mg should equal the solar ratio. Solar wind Fe/Mg is a more valid measure of solar composition than CI chondrites and can be measured more accurately than spectroscopic photospheric abundances. Mg and Fe fluences analyzed in four laboratories give satisfactory agreement. Si and diamond-like carbon collector fluences agree for both elements. The Mg and Fe fluences are 1.731 ± 0.073 × 1012 and 1.366 ± 0.058 × 1012 atoms/cm2. All plausible sources of errors down to the 1% level are documented. Our value for the solar system Fe/Mg, 0.789 ± 0.048 agrees within 1 sigma errors with CI chondrites, spectroscopic photospheric abundances, and with the solar wind data from the ACE spacecraft. CI samples from asteroid Ryugu give Fe/Mg in agreement with Genesis and meteoritic CI samples despite very small sample sizes. The higher accuracy of the Genesis solar Fe/Mg permits a comparison with chondritic Fe/Mg at the 10% level. Intermeteorite Fe/Mg averages differ among the main C chondrite groups but are within, or very close to, the ±1 sigma Genesis solar Fe/Mg.

¹B. H. Oliveira,¹J. F. Snape,¹R. Tartèse,¹J. F. Pernet-Fisher,²D. van Acken,³M. J. Whitehouse,¹K. H. Joy
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14305]
¹Department of Earth and Environmental Sciences, University of Manchester, Manchester, UK
²UCD School of Earth Sciences, University College Dublin, Dublin, Ireland
³Department of Geosciences, Swedish Museum of Natural History, Stockholm, Sweden
Published by arrangement with John Wiley & Sons

The Calcalong Creek lunar meteorite is a regolith breccia with a lithologically diverse array of clasts set in a glassy, highly vesicular matrix. Here, we present a comprehensive new analysis of the meteorite. Comparisons to remote sensing data, lunar sample lithologies, and lunar sample ages indicate that it was likely sourced from regolith surrounding the Moon’s nearside Procellarum KREEP Terrane, as opposed to the farside South Pole-Aitken basin as has been previously suggested. Partial and complete reset dates of ~3.9 Ga suggest a disturbance at this time, which aligns with that of the Imbrium basin-forming event, and to a lesser degree we see evidence of a ~4.2 Ga impact, which may be related to the formation of the Serenitatis basin. Analysis of Calcalong Creek clasts, thus, provide insights not only on the timing of major impact basin formation but also on the volcanic history of the Moon. The meteorite also samples some ancient ~4.3 Ga evolved magmatism, manifested in the presence of granophyre clasts, which may have originated from a high-μ, KREEP-like source, as well as younger, ~3.7 Ga low-Ti basaltic magmatism.