^1,2M. D. Suttle, ¹B. Brabrián
Earth and Planetary Science Letters, 697, 120415
Open Access Link to Article [DOI: 10.1016/j.epsl.2026.120415]
¹School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK
²Dipartimento di Scienze della Terra, Università di Pisa, Pisa, 56126, Italy

Copyright Elsevier

We investigate three unresolved questions in CM chondrite research: (1) what was the initial O-isotope composition of their accreted water? (2) How much water was accreted? And (3) Did aqueous alteration proceed under open or closed-system conditions? We approach this problem through numerical modelling of the aqueous alteration process using an O-isotope perspective. Our model simulates dissolution and mixing between dry rock and the fluid reservoir, secondary mineralisation (phyllosilicate and calcite) and, in some scenarios open-system evaporative loss. Previously published O-isotope measurements (CM chondrite bulk rock, and T1 and T2 calcite) and a suitable alteration extent (65–85 vol%) are used as constraints against which viable alteration scenarios must match. We find the most likely conditions for alteration were the accretion of water-ice with an approximately Earth-like composition (plotting on or close to the intersection between the TFL and the PCM) and with a δ¹⁸O value <30‰ and likely at ∼5‰, prograde conditions (increasing temperature with time), T1 formation before significant protolith was dissolved, an initial water-to-rock (mass) ratio of ∼0.6 and moderate open system evaporative water loss. The most surprising result of this study is the isotopically light (relatively ¹⁶O-rich) initial water composition. We show that this is consistent with fluid compositions independently determined from several other studies. This implies that outer Solar System water was not ubiquitously ¹⁶O-poor, as might have been expected based on the composition of isotopically anomalous cosmic symplectite found in Acfer 094.

¹Andrei Yakovlev, ¹Dmitriy Beloborodov
Icarus (in Press) Link to Article [DOI: 10.1016/j.icarus.2026.117363]
¹St. Petersburg State University, 28, Universitetskaya prospekt, St. Petersburg, 198504, Russia

Copyright Elsevier

We investigate the dynamics of levitation and horizontal transport of lunar regolith particles in the vicinity of the terminator, taking into account the radiation pressure of solar irradiation. In contrast to earlier simplified models, the radiation pressure efficiency factor Q_pr(R) is calculated based on Mie theory using experimental data for the complex refractive index of vitreous silicate that is characteristic of lunar soil. We consider a two-dimensional model of particle motion in the near-surface photoelectron sheath that incorporates electrostatic, gravitational and radiation forces. Within this framework, the dependence of the minimum levitation angle θ_min(R) on particle radius is analyzed, and numerical calculations of the maximum horizontal transport distance L_max(R) during sunrise and sunset periods are performed. Our results show that incorporating the real optical properties of particles leads to quantitative changes in the dependence of L_max(R) compared to earlier estimates. At sunset, the transport maximum is attained for particle radii of approximately 0.075 μm, whereas at sunrise a non-monotonic dependence L_max(R) appears, along with significantly larger transport distances for small particles. Our findings show that the realistic optical properties of particles have a significant impact on the spatial scales over which lunar regolith is redistributed horizontally.

¹Ai-Cheng Zhang, ¹Tian-Ran Du, ¹Lang Zhang, ¹Xiao-Wen Liu, ²Li-Ping Qin
Meteoritics & Planetary Science (in Press)
Link to Article [DOI: 10.1111/maps.70260]
¹State Key Laboratory of Critical Earth Material Cycling and Mineral Deposits, School of Earth Sciences and Engineering, Nanjing University, Nanjing, China
²State Key Laboratory of Lithospheric and Environmental Coevolution, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, China

Published by arrangement with John Wiley & Sons

Late veneer hypothesis involves a process whereby material with a generally bulk chondritic composition is added to the silicate shell of a differentiated planetary body, subsequent to core formation. Understanding the origin and extent of the putative late veneer is critical for understanding the late stages of planetary accretion and evolution. The late veneer concept was originally proposed based on the absolute and relative abundances of highly siderophile elements in whole-rock samples of Earth’s mantle, and supported by data for several other planetary bodies. No supporting mineralogical evidence, however, has been reported. Here, we report the discovery of an Ir,W,Ru,Rh-rich metal grain in early-formed unbrecciated cumulate eucrite Northwest Africa 8326. We suggest that the W-rich nature of this grain could not be a result of eucrite parent melt evolution, or due to exsolution from a pre-existing sulfide phase during cooling or S degassing. Instead, it is best explained with the addition of a chondrite-related component. The survival of this W-rich metal grain during high-temperature melting processes could be related to its high melting point. The W-rich grain in NWA 8326 represents the first mineralogical evidence, supporting the late veneer hypothesis. Refractory metal grains in unbrecciated achondrites like that reported here potentially have important impacts on the highly siderophile element patterns and isotopic modal ages of their host rocks.

^1,4Hanwei Wu, ^2,4Qiquan Yang, ¹Yi Xu, ¹Sizhe Zhao, ¹Renrui Liu, ³Tianyi Xu, ¹Xiaoping Zhang, ¹Bohan Zhou
The Astrophysical Journal Letters, 1011, L7
Open Access Link to Article [DOI: 10.3847/2041-8213/aeb028]
¹State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau 999078, People’s Republic of China
²College of Surveying & Geo-Informatics, Tongji University, Shanghai 200092, People’s Republic of China
³Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210034, People’s Republic of China

Space weathering progressively modifies lunar surface regolith, while impact gardening and related processes redistribute weathered materials within the upper regolith, generating depth-dependent variations in maturity. Although surface maturity has been extensively investigated, its variation within the uppermost few centimeters remains insufficiently characterized. In particular, whether shallow maturity profiles differ between nearside and farside, especially at mid-to-high latitudes, has yet to be systematically examined. Here, using multisource orbital and in situ observations together with sampling-derived information, we investigate the depth-dependent distribution of shallow maturity at the Chang’e-5 (CE-5) landing site on the nearside and the Chang’e-6 (CE-6) site on the farside, both located at mid-to-high latitudes. Prelanding orbital spectra characterize the undisturbed surface, whereas in situ spectra acquired after plume-induced erosion (∼0.4/0.7 cm depth) and sampling excavation (∼3.4/3.7 cm depth) provide information on deeper layers, enabling maturity comparisons across three shallow stratigraphic horizons. Maturity indicators consistently indicate that the shallow regolith of CE-6 is more mature than that of CE-5, with the postlanding in situ spectra yielding I_s/FeO values of ∼78.13 and ∼31.40 for CE-6 and CE-5, respectively. Despite this difference in overall maturity, both sites exhibit similar depth-dependent patterns: the regolith becomes fresher with depth, showing relatively small maturity changes following plume erosion and more pronounced changes after sampling excavation. The similarity in these vertical patterns suggests broadly comparable intensities of two sites’ shallow regolith modification. These findings provide new observational constraints on the vertical distribution and evolution of shallow maturity and advance our understanding of regolith modification of CE-5 and CE-6 sites.

¹Kate Y. L. Su, ^2,3Attila Moór, ^2,3Ágnes Kóspál, ^4,5George H. Rieke, ⁴Antranik A. Sefilian, ⁵Renu Malhotra, ^5,6Ilaria Pascucci, ⁶Alan P. Jackson, ^2,3,7Péter Ábrahám, ^1,8Nicholas P. Ballering
The Astrophysical Journal, 1010, 1
Open Access Link to Article [DOI: 10.3847/1538-4357/ae88fe]
¹Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301, USA
²Konkoly Observatory, HUN-REN Research Centre for Astronomy and Earth Sciences, MTA Centre of Excellence, Konkoly-Thege Miklós út 15-17, 1121 Budapest, Hungary
³CSFK, MTA Centre of Excellence, Budapest, Konkoly Thege Miklós út 15-17., H-1121, Hungary
⁴Department of Astronomy and Steward Observatory, University of Arizona, Tucson, AZ 85721, USA
⁵Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721, USA
⁶Department of Physics, Astronomy, and Geosciences, Towson University, 8000 York Road, Towson, MD, USA
⁷Department of Astrophysics, University of Vienna, Türkenschanzstr. 17, A-1180 Vienna, Austria
⁸Department of Astronomy, University of Wisconsin-Madison, Madison, WI 53706, USA

Debris disks are dusty structures around mature stars, primarily identified by infrared excesses in the stellar spectra. A subset, known as extreme debris disks (EDDs), exhibits stochastic infrared variability, believed to result from large-scale violent collisions that contribute to the formation or destruction of rocky planetary bodies. We analyze JWST and Spitzer mid-infrared spectra for 21 EDDs to investigate the connection between impact-produced dust mineralogy and the age and dynamical state of these systems during various stages of planet formation and evolution. Our findings indicate that EDDs contain significantly more optically thin, small dust grains compared to those typically seen in protoplanetary and debris disks. Predominantly submicron in size, these grains are thermally altered, as shown by their high levels of silica and crystalline silicate composition. Along with stochastic infrared variability, these features define EDDs as a subclass of debris systems where dust is generated from large collisions between Moon- and Mars-sized bodies. Our results not only provide a diagnostic information about the physical conditions of violent events during terrestrial planet formation, aiding in differentiating the complex outcomes of these impacts, but also offer a potential marker for identifying planetary systems experiencing dynamical instability.

¹Zichen Wei, ¹Hao Zhang
The Astrophysical Journal, 1010, 63
Open Access Link to Article [DOI: 10.3847/1538-4357/aea69a]
¹Hubei Key Laboratory of Planetary Geology and Deep-Space Exploration, School of Earth and Planetary Sciences, China University of Geosciences, Wuhan, 430074, People’s Republic of China

We present a coordinated laboratory optical data set for three equilibrated ordinary chondrites (OCs; LL5/6, L6, and H6), including the recently witnessed Maoming fall of 2025 May 28, to investigate the coupled effects of grain size, surface structure, and simulated space weathering on their spectral, photometric, and polarimetric properties. Intact slabs and three grain-size fractions were measured in the fresh state and after two levels of pulsed-laser irradiation using Fourier-transform infrared reflectance spectroscopy, bidirectional reflectance distribution function (BRDF) measurements, and polarization phase curves. Irradiation generally produces spectral darkening, reddening, and weakening of the 1 and 2 μm absorption bands, although the degree of reddening depends on both composition and grain size. BRDF measurements reveal a systematic transition from nearly isotropic scattering in fine powders to enhanced backscattering in coarse powders and pronounced specular reflection from slabs. These scattering characteristics remain largely unchanged after irradiation, indicating that grain size and surface structure exert stronger control on angular scattering than irradiation-induced optical darkening. The specular component is strongly suppressed in the irradiated LL5/6 slab but remains evident in the L6 and especially H6 slabs, suggesting a contribution from metal-rich phases. Polarimetric measurements further show systematic differences between slabs and powders, with surface morphology influencing both the negative-polarization branch and the large-phase-angle polarization behavior. This dataset demonstrates that grain size and surface structure are as important as composition and space weathering in governing the optical properties of OCs, providing complementary constraints for interpreting OC-like asteroid surfaces.

¹Benjamin N. L. Sharkey, ²Vishnu Reddy, ³John W. Noonan, ⁴Theodore Kareta, ¹James M. Bauer, ⁵Bryan J. Holler, ¹Yaeji Kim, ⁶Albert R. Conrad
The Astrophysical Journal Letters, 1010, L31
Open Access Link to Article [DOI: 10.3847/2041-8213/aea6b6]
¹Department of Astronomy, University of Maryland College Park, MD 20742-2421, USA
²Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
³Department of Physics, Edmund C. Leach Science Center, Auburn University, Auburn, AL, USA
⁴Department of Astrophysics and Planetary Science, Villanova University, Villanova, PA, USA
⁵Space Telescope Science Institute, Baltimore, MD, USA
⁶Large Binocular Telescope Observatory, Tucson, AZ, USA

Near-Earth asteroid (469219) Kamoʻoalewa is a uniquely stable quasi-satellite of the Earth and a target of the Tianwen-2 spacecraft mission. Here we report observations taken with JWST’s NIRSpec instrument in integral field unit (IFU) mode in 2026 February. The JWST reflectance spectrum is notably less red (more neutral) from 1.0 to 2.5 μm than previous ground-based spectrophotometric observations. New observations made with the Large Binocular Telescope (LBT) in 2026 April, observed and processed similarly to the 2021 observations, find zJ colors in agreement with JWST. Kamoʻoalewa’s infrared colors appear more similar to typical silicate-rich asteroids and unlike the reddened, space-weathered lunar-like silicates suggested by previous observations. In agreement with the ground-based spectrum, we detect a faint silicate absorption feature at 0.93 ± 0.01 μm. We do not detect a 2.0 μm silicate absorption. Models of Kamoʻoalewa’s faint thermal emission (beginning near 4.5 μm) find a mean diameter of D = 18 ± 2 m and best-fit visible albedo p_V = 0.59^+0.25_−0.17, with models as low as p_V = 0.36 providing adequate model fits. This combination of color, albedo, and absorption bands is similar to oldhamite-bearing enstatite-rich compositions. Kamoʻoalewa’s brightness variations over the course of the JWST program provide independent confirmation of its rotation period of 27.9 minutes, with an axis ratio ∼1.4 (D ∼ 15–21 m).

^1,2,3,7Harshit Krishna, ^1,2,4,7Asmit Gupta, ^1,2,5Sneha Bhowmick, ^1,2,6Chandan K. Sahu, ^1,2Sudipta Midha, ^1,2Liton Majumdar
The Astrophysical Journal, 1010, 23
Open Access Link to Article [DOI: 10.3847/1538-4357/ae9ba8]
¹Exoplanets and Planetary Formation Group, School of Earth and Planetary Sciences, National Institute of Science Education and Research, Jatni 752050, Odisha, India
²Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai 400094, India
³Department of Physical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, Sahibzada Ajit Singh Nagar, Punjab 140306, India
⁴Indian Institute of Science Education and Research, Kolkata, Mohanpur 741246, West Bengal, India
⁵Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur 721302, India
⁶Department of Geosciences, Pennsylvania State University, University Park, State College, PA 16802, USA
⁷Harshit Krishna and Asmit Gupta contributed equally to this work.

Over the past three decades, hundreds of rocky exoplanets have been discovered. Some of these show atmospheric signatures indicative of diverse chemical compositions. Interpreting these atmospheres requires a physically grounded understanding of planetary interiors, as interior composition and mineralogy govern the formation and evolution of secondary atmospheres. Rocky terrestrial exoplanets are expected to inherit the refractory composition of their host stars, providing a direct pathway to constrain their bulk composition and mineralogy. However, a large fraction of these planets orbit M-type stars, whose compositions remain poorly constrained because of limited and uncertain stellar abundance measurements. Here, we present a physically consistent framework that connects stellar abundances to the interior structure and mineralogy of rocky exoplanets by combining stellar abundance inference, devolatilization modeling to estimate bulk and mantle elemental abundances, interior structure calculations to derive pressure–temperature (P–T) profiles, and thermodynamic equilibrium modeling of mantle mineralogy. We first benchmark the framework against Earth and then apply it to the super-Earth GJ 486b using chemically consistent abundances derived from ensembles of similar M-dwarf hosts. We find that GJ 486b likely hosts an iron-rich and silica-poor mantle relative to Earth while preserving the major mantle phase transitions. Sensitivity analyses show that the overall mineralogical structure is robust to variations in bulk composition and P–T profiles, with temperature primarily modulating phase proportions near key transitions. Our results demonstrate that stellar chemical abundances, when combined with physically motivated devolatilization models, provide robust constraints on planetary interior composition and mineralogy beyond those obtainable from mass and radius measurements alone. This framework establishes a physically motivated foundation for linking rocky exoplanet interiors to atmospheric characterization in the JWST era.

¹C. D. O’Connell-Cooper et al. (>10)
Journal of Geophysical Research (Planets)(in Press) Open Access Link to Article [https://doi.org/10.1029/2025JE009001]
¹Planetary and Space Science Centre, University of New Brunswick, Fredericton, NB, Canada
Published by arrangement with John Wiley & Sons

The Mount Sharp group in Gale crater is typically interpreted to record a progressive change (with increasing elevation) from wetter fluvio-lacustrine environments to dry, eolian environments. This shift has been linked to orbital evidence for a global change in environmental and depositional conditions leading to an overall drying out of Mars. The Mars Science Laboratory Curiosity rover has documented evidence at Gale for the periodic continuation of aqueous depositional processes within the Mount Sharp group within the Clay Sulfate Transition, suggesting that, in Gale crater, it was not a simple, unidirectional drying out pattern. We present data on a series of interdune lenses at Gale crater, providing a window into locally changing environmental conditions. They represent wet (fluvial to lacustrine) deposits in the otherwise dry eolian Contigo dune field. Alpha Particle X-Ray Spectrometer geochemical data reveal compositional similarities between the interdune lenses and both the host Contigo member and unaltered basaltic sediments. Modeling indicates that the lenses may contain up to 52% basaltic sands/soils mixed with local sediment. A high degree of homogeneity in composition and sedimentary structures are identified across the lenses. This suggests a common source of influx material and a repeated process (wet episodes in a dry environment over several cycles of seasonal variations). Furthermore, differences in composition between the interdune lenses and the host Contigo member help to elucidate the timing of alteration within the Mount Sharp group.

¹Haijun Li,¹Huapei Wang
Journal of Geophysical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2024JE008768]
¹Paleomagnetism and Planetary Magnetism Laboratory, School of Geophysics and Geomatics, China University of Geosciences, Wuhan, China
Published by arrangement with John Wiley & Sons

Meteorites preserve valuable remanent magnetization from the early solar system. However, the residence on the Earth’s surface often leads to the formation of iron oxides, which can alter or obliterate the primary remanence and complicate the paleomagnetic data interpretation. The weathering degree varies significantly depending on residence time, location, climate, and the chemical composition of the meteorite. Additionally, individual meteorites can exhibit varying oxidation degrees within a single stone due to partial burial in soil. This study examines the LL7 chondrite Northwest Africa 12780, revealing heterogeneous weathering across different parts of the meteorite. While one part shows extensive metal oxidation, another remains unoxidized. Although most oxidized subsamples contain paramagnetic iron oxides, maghemite is observed in some oxidized subsamples. Our findings highlight the presence of heterogeneous weathering in meteorites, which leads to the formation of various iron oxides, including maghemite, potentially acquiring chemical remanent magnetization and overprinting primary remanence. This also indicates that certain subsamples may retain their primary remanence even in weathered meteorites. However, systematic investigations are necessary to eliminate the influence of ferromagnetic iron oxides.