¹Jamaledin Baniamerian,¹Sebastian E. Lauro,¹Barbara Cosciotti,¹Alessandro Brin,²Carlo Lefevre,¹Elisabetta Mattei,¹Elena Pettinelli
Journal of Geophysical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2024JE008545]
¹Dipartimento di Matematica e Fisica, Università degli studi Roma Tre, Rome, Italy
²Istituto di Astrofisica e Planetologia Spaziali di Roma, (INAF/IAPS), Rome, Italy
Published by arrangement with John Wiley & Sons

Radar sounder investigations of Venus’ crust are particularly challenging, due to the expected high loss character of the rocks at temperatures of hundreds of degrees. The dielectric behavior of hot planetary analogues is poorly understood, as the procedure to measure such samples is difficult, especially in the frequency range of 1–100 MHz typical of planetary radar sounders. In this paper a new experimental setup capable of measuring the complex dielectric permittivity of rock slices at temperatures as high as
C, in a large frequency range is presented. The measurements are based on the open-ended coaxial transmission line approach, where the sample is kept inside an oven to reach thermal equilibrium, and the probe tip is placed in contact with the rock and rapidly removed to limit heat propagation along the probe. The dielectric quantities (real part of permittivity and loss tangent) are computed by inverting the scattering parameters measured with a Vector Network Analyzer. Experimental data are compared with electromagnetic simulations, to define the probe characteristics and its criticalities. To assess the reliability of the setup, the results are validated using Macor ceramic samples for which dielectric properties have been measured and certified at different temperatures and frequencies. The methodology is then applied to a basaltic rock sample to demonstrate its applicability to potential Venusian analogues. The proposed technique instills confidence in the possibility of exploring the complex permittivity parameter space of many igneous and sedimentary rocks at high temperatures.

^1,2,3Qi Sun,^4,5Yu-Yan Sara Zhao,^6,7Kesong Ni,^6,7Zonghao Wang,⁸Wen Yu,⁹Wenqi Luo,⁹Wenbin Yu,⁹Xin Nie,⁹Zonghua Qin,^9,2,5Quan Wan
Journal of Geophysical Research (Planets) Link to Article [https://doi.org/10.1029/2025JE009023]
¹State Key Laboratory of Critical Mineral Research and Exploration, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
²University of Chinese Academy of Sciences, Beijing, China
³School of Chemistry and Chemical Engineering, Guizhou University, Guiyang, China
⁴Research Center for Planetary Science, College of Earth and Planetary Sciences, Chengdu University of Technology, Chengdu, China
⁵CAS Center for Excellence in Comparative Planetology, Hefei, China
⁶Hypervelocity Aerodynamics Institute, China Aerodynamics Research and Development Center, Mianyang, China
⁷National Key Laboratory of Aerospace Physics in Fluids, Mianyang, China
⁸Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
⁹State Key Laboratory of Critical Mineral Research and Exploration, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
Published by arrangement with John Wiley & Sons

Impact events involving phyllosilicates, whether present in targets or impactors, are highly probable on various celestial bodies. While impact melting is considered the most important metamorphic feature in shocked phyllosilicates, lack of understanding of this process represents a substantial impediment to constraining shock conditions from melted phyllosilicates and to inferring surface evolution of celestial bodies. To investigate shock metamorphism of phyllosilicates, cratering experiments were conducted on clinochlore targets using a light-gas gun at impact velocities ranging from 0.8 to 7.0 km·s−1, and the shocked fragments were characterized with electron microscopy, X-ray diffraction (XRD), Raman spectroscopy and near-infrared spectroscopy. Clinochlore underwent melting at a low velocity of 0.8 km·s−1 due to localized energy concentration at the micron-scale projectile-target interface. With increasing velocity up to 7.0 km·s−1, the shock-generated glasses evolved from semi-parallel nanofilaments to complex agglutinate-like layers, within which abundant vesicles were present due to shock-induced dehydroxylation. Submicroscopic metallic particles were pervasive in the agglutinate-like layers, possibly owing to melting and solidification of micro-jetted metallic fragments. In line with the morphological characterization results, XRD patterns, near-infrared reflectance spectra and Raman spectra of the shocked fragments also collectively reflect the presence and evolution of the impact glasses. Beneath the impact glasses, shock metamorphism may be indicated by decreased basal spacings of clinochlore in the unmelted matrices. Additionally, olivine bearing exogenous iron composition from projectiles crystallized from high-temperature melts during secondary impacts. This work may provide important constraints for regolith evolution and impact history of extraterrestrial bodies.

¹Dijun Guo,^1,2Yeming Bao,¹Xing Wu,³Shuai Li,^1,2,4Yang Liu,¹Yazhou Yang,¹Yuchen Xu,¹Feng Zhang,^4,5Jianzhong Liu,¹Yongliao Zou
Journal of Geophysical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2024JE008690]
¹State Key Laboratory of Solar Activity and Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing, China
²University of Chinese Academy of Science, Beijing, China
³Hawaii Institute of Geophysics and Planetology, University of Hawaiʻi at Mānoa, Honolulu, HI, USA
⁴Center for Excellence in Comparative Planetology, Chinese Academy of Sciences, Hefei, China
⁵Center for Lunar and Planetary Science, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
Published by arrangement with John Wiley & Sons

Ferroan anorthosite, the dominant component of the primordial lunar crust, provides valuable evidence for the lunar magma ocean (LMO) theory. Despite its adjacency to the feldspathic highlands terrane, the identification of pure anorthosite in the Apollo basin has been scarce. Through a comprehensive investigation with high-resolution Kaguya Multiband Imager data over the Apollo basin, we identified numerous outcrops exhibiting definitive diagnostic absorption indicative of the presence of ferroan anorthosite. These anorthosite exposures suggest that crustal material remained after the South Pole-Aitken (SPA) basin impact and that the mafic-rich SPA ejecta was thin in the area, providing significant insights into the excavation process of the SPA impact and subsequent evolution. Our results suggest that the Chang’e-6 mission could potentially bring back the primordial crustal anorthosite from the Apollo basin and offer valuable insights into the LMO theory, alongside the mantle material excavated by the massive SPA impact.

¹Alice C. Quillen,¹Sean Doran
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.70006]
¹Department of Physics and Astronomy, University of Rochester, Rochester, New York, USA
Published by arrangement with John Wiley & Sons

We measure ejecta mass as a function of azimuthal and impact angle for 104 m/s oblique impacts into sand. We find that the ejecta mass distribution is strongly sensitive to azimuthal angle, with as high as eight times more mass in ejecta on the downrange side compared to the uprange side. Crater radii, measured from the impact point, are measured at different impact and azimuthal angles. Crater ejecta scaling laws are modified to depend on azimuthal and impact angle. We find that crater radii are sensitive to both impact and azimuthal angle, but the ejecta mass as a function of both angles can be estimated from the cube of the crater radius without an additional angular dependent function. The ejecta distributions are relevant for processes that depend upon the integrated properties of approximately 100 m/s impacts occurring in the outer solar system and possibly during planetesimal formation.

¹Qin Zhou et al. (>10)
Nature 643, 371-375 Open Access Link to Article [DOI https://doi.org/10.1038/s41586-025-09131-7]
¹Key Laboratory of Lunar and Deep Space Exploration, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, China

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

¹Huicun He et al. (>10)
Nature 643, 366-370 Open Access Link to Article [DOI https://doi.org/10.1038/s41586-025-08870-x]
¹Key Laboratory of the Earth and Planetary Physics, Chinese Academy of Sciences, Beijing, China

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

^1,2Shuhui Cai et al. (>10)
Nature 643, 361-365 Open Access Link to Article [DOI https://doi.org/10.1038/s41586-024-08526-2]
¹State Key Laboratory of Lithospheric and Environmental Coevolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
²College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China

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

¹Qian W. L. Zhang et al. (>10)
Nature 643, 356-360 Open Access Link to Article [DOI https://doi.org/10.1038/s41586-024-08382-0]
¹State Key Laboratory of Lithospheric and Environmental Coevolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China

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

^1,2Yiheng Dai,^1,2Zhiheng Xie,^1,2Zezhou Li,^2,3Tianyi Jia,^2,3Ruimin Wang,⁴Zongjun Yin,^2,3Bing Shen,^1,2Jihan Zhou
Journal of Geophysical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2025JE009028]
¹Beijing National Laboratory for Molecular Sciences, Center for Integrated Spectroscopy, College of Chemistry and Molecular Engineering, Peking University, Beijing, China
²Research Institute of Extraterrestrial Material at Peking University (RIEMPKU), Beijing, China
³Ministry of Education Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing, China
⁴State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China
Published by arrangement with John Wiley & Sons

Meteoroid impacts, a key process of space weathering, significantly alter the structures, compositions and properties of lunar regolith. However, the phase separation phenomena, common in lunar regolith and induced by impact, remain poorly understood. This uncertainty arises from the structural complexity and the scarcity of identified impact-induced phase separation features. Here we report the impact-induced formation of chemically distinct amorphous silicate nanodroplets, including iron-rich droplets within a silicon-rich glass matrix and vice versa, on the surface of a Chang’e-5 lunar regolith grain. These nanodroplets are partially ripened aggregates, and their formation is attributed to metastable liquid immiscibility driven by local chemical heterogeneities and rapid quenching. Additionally, troilite-kamacite remnants and skeletal crystallites of ilmenite and apatite provide direct evidence of impact and fast post-impact quenching, respectively. These findings suggest that quenched impact melts in airless bodies can undergo unmixing, forming immiscible conjugated nanodroplets, and exhibiting diverse behaviors under specific post-impact conditions.

¹Xue Su,¹Youxue Zhang,²Yang Liu,¹Robert M. Holder
Journal of Geophysical Research (Planets)(in Press) Open Access Link to Article [https://doi.org/10.1029/2025JE009027]
¹Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA
²Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
Published by arrangement with John Wiley & Sons

Volcanic glass beads on the Moon have traditionally been thought to only record volatile loss during pyroclastic eruptions. However, recent discoveries have shown that lunar orange glass beads, representing primitive high-Ti basalts, experienced both outgassing and in-gassing of volatile elements such as Na, K, Cu, and S. In this work, we examine lunar green glass beads from samples 15421 and 15366, representing primitive very-low-Ti basalts, for the distribution of Na, K and Cu using EMP analyses and LA-ICP-MS mapping. It is found that all studied lunar green beads show increased Na, K and Cu concentrations near the bead surfaces, indicative of in-gassing. A quantitative model was developed to simulate the concentration evolution of Na and Cu in individual green glass beads during eruption and cooling. The presence of similar in-gassing diffusion profiles of volatile elements in beads from different eruptions indicates a common behavior of lunar volcanic gas. In addition to volatile in-gassing, LA-ICP-MS mapping of Na and K in one green bead from sample 15366 shows features suggesting collision of melt droplets during the fire-fountain eruption, revealing more details in the dynamic aspects of lunar fire-fountain eruptions. Compared to orange glass beads, the varying boundary conditions of green glass beads during formation may suggest that their eruption plume evolved and dissipated more rapidly, potentially linked to changes in the global lunar atmosphere.