¹Sylvain Laforet,¹Hugues Leroux,¹Corentin Le Guillou,²Maya Marinova,¹Adrien Néri,¹Adrien Teurtrie,¹Francisco de la Peña,¹Damien Jacob,²Alexandre Fadel,³David Troadec
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.14366]
¹Université de Lille, CNRS, INRAE, Centrale Lille, UMR 8207-UMET-Unité Matériaux et Transformations, Lille, France
²Université de Lille, CNRS, INRAE, Centrale Lille, Université Artois, FR 2638-IMEC-Institut Michel-Eugène Chevreul, Lille, France
³Université de Lille, CNRS, Centrale Lille, Junia, Univ. Polytechnique Hauts-de-France, UMR 8520 – IEMN – Institut d’Electronique de Microélectronique et de Nanotechnologie, Lille, France
Published by arrangement with John Wiley & Sons

The first few microns of the surface of airless bodies are subject to severe changes due to the harsh environment of space, known as space weathering. The Hayabusa2 sample return mission from the asteroid Ryugu provides the first opportunity to study these effects on a carbonaceous and hydrated body. Understanding the structural and chemical changes that occur in the space weathered layers of Ryugu is crucial to correctly interpreting the mechanisms involved in such processes. This study employs transmission electron microscopy to achieve the spatial resolution necessary to analyze the nanoscale heterogeneities in these modified layers. The chemical analyses indicate that features present are likely to represent the spattering of a Ryugu-like material, possibly from a different lithology of the asteroid. However, such material appears to be completely dehydroxylated and depleted in sulfur by approximately 20%. Furthermore, the nanoscale dispersion of vesicles and rounded nanosulfides found in these melt layers helps to estimate the temperatures (>1300°C) and the time scales (<10−8 s) involved in their formation. In addition, this study describes and discusses a unique spherical feature not previously observed in Ryugu samples. The 3 μm-sized object shows strong similarities to microchondrules observed in some carbonaceous (CM2) and ordinary chondrites, suggesting a divergent thermal history from that of the melt layers.