^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.

¹V. V. Kachmar, ^1,2,3,4B. L. Ehlmann
Journal of Geophysical Research: Planets, 131, e2025JE009415
Open Access Link to Article [DOI: 10.1029/2025JE009415]
¹Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
²Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, CO, USA
³Department of Geological Sciences, University of Colorado Boulder, Boulder, CO, USA
⁴Department of Astrophysical and Planetary Sciences, University of Colorado Boulder, Boulder, CO, USA

Published by arrangement with John Wiley & Sons

Water ice deposits occur on inner solar system bodies in sunlit and shadowed terrains. We develop approaches to remotely determine the mixing mode with regolith (areal vs. intimate), ice grain size, and abundance that reveal processes of ice formation, emplacement, and evolution. Given the sensitivity of existing inversion techniques to the accuracy of absolute wavelength-dependent reflectance, we evaluated and parameterized robust observables between 1.2 and 2.5 μm—band depth and band area at 1.5 and 2.0 μm, and near-infrared spectral slope—based on Hapke equations, using a data-derived regolith endmember mixed with modeled ice of varying properties. As a case study, we applied the approach to three lunar polar craters with permanent shadows—de Gerlache, Faustini, and Rozhdestvenskiy—and, in a separate companion publication, to ice on Ceres (Kachmar & Ehlmann, 2026, https://doi.org/10.1029/2025JE009421). Our inferred abundances for lunar ice (10–30 wt%, 10–100 μm) are in agreement with the ShadowCam results. The derivation of the mixing mode, grain size, and abundance is robust (<20 wt% difference) to choices or uncertainties about ice crystallinity, temperature, and regolith endmember, and is only moderately sensitive to porosity. In contrast, the model choices for surface illumination (Sun vs. shadow), ice optical constants, and phase behavior (isotropic vs. anisotropic) substantially influence the results. The approach can be applied to any planetary infrared spectroscopic data set, and its promise will be fully realized with refined ice optical constants and laboratory tests with ice-regolith mixtures at various porosities and observational geometries.

^1,2K. A. Cone et al. (>10)
Journal of Geophysical Research: Planets, 131, e2026JE009701
Open Access Link to Article [DOI: 10.1029/2026JE009701]
¹Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY, USA
²Earth, Environmental and Planetary Sciences, Rice University, Houston, TX, USA

Published by arrangement with John Wiley & Sons

Hypervelocity impacts modify planetary crusts and can alter the microstructures of key minerals used to reconstruct planetary histories. We investigated the potential effects of impacts on three common accessory minerals found in terrestrial crusts by experimentally shocking zircon, apatite, and whitlockite at 5, 10, 20, and 40 GPa. The internally consistent suite of shock-metamorphosed microstructures was characterized using scanning electron microscopy, Raman spectroscopy, electron backscatter diffraction, and in situ U-Pb isotope analysis. Crystal orientation mapping reveals patchy reidite formation near zircon grain exteriors at 20 GPa and pervasive reidite domains at 40 GPa. Annealing sharpens the characteristic ∼1,006 cm⁻¹ zircon Raman peak at ≤20 GPa but does not restore this peak in the reidite formed at 40 GPa. Apatite retains crystalline domains through 40 GPa despite broadening of some Raman bands at ∼1,051 and ∼1,145 cm⁻¹, with annealing restoring spectra to pre-shock patterns. Whitlockite develops merrillite-like Raman spectra with pressure, but the data cannot resolve dehydrogenation or transformation to merrillite. Shocked zircon exhibits U-Pb discordance, whereas annealing at 950°C improves concordance, suggesting that shock-induced microstructural modification may produce matrix effects and apparent age offsets, complicating reconstruction of events such as a lunar bombardment. Collectively, these experiments also demonstrate heterogeneity in mineral responses—both among and within grains—to a single shock pressure. Thus, the absence of a diagnostic microstructure within analyzed domains does not necessarily preclude exposure to an associated shock pressure, emphasizing the importance of whole-grain micro- to nanoscale characterization and consideration of grain size in shocked planetary materials.

^1,2,3S. Andrejkovičová et al. (>10)
Journal of Geophysical Research: Planets, 131, e2025JE009610
Open Access Link to Article [DOI: 10.1029/2025JE009610]
¹NASA GSFC, Greenbelt, MD, USA
²CRESST, University of Maryland, College Park, MD, USA
³Geosciences Department, GeoBioTec, Aveiro University, Aveiro, Portugal

Published by arrangement with John Wiley & Sons

Ammonium (NH₄⁺) in the interlayer space of phyllosilicates has been proposed as a potential but underexplored nitrogen reservoir on Mars. We synthesized ammonium-exchanged smectites (montmorillonite SWy-2 and nontronite NAu-2) and analyzed them, both as pure phases and in mixtures containing five or 20 wt.% magnesium (Mg) perchlorate, under Sample Analysis at Mars (SAM)–like conditions using evolved gas analysis–mass spectrometry (EGA) and pyrolysis (GC-MS), complemented by FTIR, XRD and EA-IRMS. Ammoniated smectites released N₂ during heating even without perchlorate, whereas mixtures with Mg perchlorate yielded oxidized nitrogen species (NO and N₂O) along with N₂. The temperature ranges and release profiles of NO bear similarities to several Gale crater samples analyzed by SAM, suggesting that part of the martian NO could derive from ammonium-bearing smectites rather than exclusively from nitrate thermal decomposition. Quantitative analysis of EGA data indicates that 4.20%–29.8% of the total nitrogen in the ammoniated smectites was released as NO under SAM-like pyrolysis, depending on smectite type and oxidant abundance. XRD under dry conditions shows partial collapse of basal spacing to d(001) ≈10.8 Å (NH₄SWy-2) and 10.4 Å (NH₄NAu-2), comparable to the broad ∼10 Å peaks observed by the Chemistry and Mineralogy (CheMin) instrument in clay-bearing Gale crater materials. These results indicate that ammonium-bearing smectites are a plausible precursor phase capable of generating NO under SAM-like pyrolysis conditions and could contribute to martian nitrogen cycling in environments where smectite formation and ammonium exchange occurred, although the present martian data do not uniquely distinguish among possible nitrogen precursor phases.