¹R. Christoffersen,²M. J. Loeffler,^1,3S. Kanee,⁴C. J. Cline II,⁴L. P. Keller,¹T. M. Erickson,^5,6J. Fontanese,⁷T. Munsat,^5,6M. Horányi
Journal of Geophysical Research: Planets Open Access Link to Article [https://doi.org/10.1029/2025JE009257]
¹Amentum, NASA Johnson Space Center, Houston, TX, USA,
²Department of Astronomy and Planetary Science, NorthernArizona University, Flagstaff, AZ, USA,
³Now at Department of Earth & Environment, Boston University, Boston, MA,USA,
⁴NASA Johnson Space Center, Houston, TX, USA,
⁵Laboratory for Atmospheric and Space Physics, University ofColorado, Boulder, CO, USA,
⁶NASA SSERVI’s Institute for Modeling Plasma, Atmospheres and Cosmic Dust(IMPACT), University of Colorado, Boulder, CO, USA,
⁷Department of Physics, University of Colorado, Boulder,CO, USA
Published by arrangement with John Wiley & Sons

The flux of solar system meteoroids is dominated by objects less than 1 mm in diameter whose impact effects play a major role in the space weathering of airless body surfaces. These effects remain poorly characterized with respect to their dependence on the range of impact speeds for meteoroids across the inner solar system. We investigated this dependence specifically for the mineral olivine using an electrostatic dust accelerator to bombard olivine single crystals with a stream of Fe metal dust particles traveling at measured speeds between 0.3 and 20 km s⁻¹. The impacting particles produced microcraters 0.2–5.2 μm in diameter whose content of impact melt, and brittle/ductile shock-induced deformation features, were characterized by scanning and transmission electron microscopy. While particles traveling <1 km s⁻¹ were not able to form microcraters, analysis of the size versus speed relations for the faster particles allowed their impact speeds and maximum shock pressures to be statistically constrained. Microcraters 0.2–0.5 μm in diameter contain olivine-composition shock melt estimated to have formed at impact speeds as high as 15–20 km s⁻¹, and shock pressures more than 250 GPa. Transmission electron microscope studies of shock melt in larger, ∼1.5 μm diameter, microcraters found it was free of impact-generated nanophase metallic Fe (npFe⁰). The impact speeds for these craters of 3.0–5.0 km s⁻¹ suggest that in asteroid regoliths dominated by olivine, still higher impact speeds may be necessary to allow npFe⁰ to be produced.

¹F. Alberquilla et al. (>10)
Journal of Geophysical Research: Planets 131, e2025JE009515 Open Access Link to Article [https://doi.org/10.1029/2025JE009515]
¹IBeA Research Group (Ikerkuntza eta Berrikuntza Analitikoa ‐ Analytical Research and Innovation), Department ofAnalytical Chemistry, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain
Published by arrangement with John Wiley & Sons

The study of terrestrial lava tubes is essential for understanding geological processes occurring during volcanic activity on other planetary bodies, such as Mars. These processes lead to the formation of minerals analogous to those found on other planets. Volcanic eruptions are often associated with hydrothermal activity and gas emissions (e.g., CO2, SO2, H2S, HCl, H2O, H2) through fumaroles, which can simulate Martian atmospheric conditions. These gases and fluids interact with the host rock, leading to mineral alteration and the formation of secondary minerals. This study analyzes the Cueva del Vidrio lava tube on La Palma (Canary Islands, Spain), formed during the 1949 San Juan eruption. Although its materials exhibit low alteration due to their relatively recent origin, the 2021 Tajogaite eruption introduced new gas emissions, groundwater interactions, and surface runoff, thereby promoting the formation of alteration crusts and coatings. The methodology combined minimally invasive techniques, such as X-ray diffraction, and non-destructive techniques, including X-ray fluorescence (μEDXRF) and Raman spectroscopy. In order to facilitate the interpretation of the results, runoff waters were analyzed by ion chromatography. The results highlight the presence of carbonates, sulfates, and iron oxides, notably hematite, which likely formed from silicate weathering, particularly olivine alteration, leading to iron depletion and magnesium enrichment. Additionally, amorphous silica was identified, likely formed through reactions involving sulfate and carbonate precipitation, which leached silicon from silicate-rich host rocks. Similar processes have been described on Mars, where opal is considered a key mineral for astrobiological investigations due to its potential for preserving biosignatures.

¹Mehmet Yesiltas,²Andrew Dopilka,²Robert Kostecki,¹Timothy D. Glotch,¹Paul Northrup
Proceedings of the National Academy of Sciences of the USA (PNAS) 123, e2601891123 Link to Article [https://doi.org/10.1073/pnas.2601891123]
¹Department of Geosciences, Stony Brook University, Stony Brook, NY 11794
²Energy Technologies and Systems Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720

Asteroid Bennu preserves primitive material from the early solar system, and returned samples allow direct examination of how organics and minerals were assembled and altered. We applied nanoscale infrared spectroscopy together with Raman spectroscopy to the Bennu sample OREX-800066-3 to characterize chemical variability at ~20 nm scales. Analysis of nano-Fourier-transform infrared spectroscopy spectra identifies three recurring compositional domains; aliphatic-rich, carbonate-rich, and nitrogen-bearing organic-rich regions. Statistical evaluation shows that these domains are compositionally and spatially distinct at the nanoscale, with strong negative correlations between aliphatic signatures and both carbonates and N-bearing organics, and negligible correlation between carbonates and N-bearing organics. Organosulfur compounds are spatially restricted to carbonate-rich regions, indicating organic-sulfate interactions during late-stage brine evolution. Raman spectra indicate highly disordered, thermally minimally metamorphosed carbonaceous matter, consistent with preservation of labile functional groups. These results demonstrate that Bennu’s angular lithology (characterized by planar facets and sharp edges) is not chemically uniform and records heterogeneous aqueous alteration rather than pervasive uniform processing. N-bearing organic functional groups are widely preserved despite extensive alteration, and carbonate-rich areas show intimate nanoscale mixing of different carbonate species. The coexistence of distinct organic- and carbonate-rich domains suggests contributions from both primordial compositional diversity and subsequent rock–fluid interaction. Comparison with Ryugu samples highlights shared features but key differences in organic-carbonate associations and carbonate distributions. Overall, Bennu’s nanoscale heterogeneity provides constraints on organic preservation, carbonate formation, organic-sulfate chemistry, and parent-body evolution in volatile-rich early solar system materials.