Compositional heterogeneity of insoluble organic matter extracted from asteroid Ryugu samples

Publication

Reference: Quirico E., Bonal L., Kebukawa Y., Amano K., Yabuta H., and many co-authors (2024). Compositional heterogeneity of insoluble organic matter extracted from asteroid Ryugu samples. Meteorit. Planet. Sci., submitted for publication.

Names

Title: Compositional heterogeneity of insoluble organic matter extracted from asteroid Ryugu samples
Abstract: We report a Fourier-Transform InfraRed analysis of functional groups in insoluble organic matter (IOM) extracted from a series of 100-500 µm Ryugu grains collected during the two touchdowns of February 22 and July 11 2019. IOM extracted from most of the samples is very similar to IOM in primitive CI, CM and CR chondrites, and show that the extent of thermal metamorphism in Ryugu regolith was, at best, very limited. One sample displays chemical signatures consistent with a very mild heating, likely due to impacts. We also report a lower carbonyl abundance in Ryugu IOM samples compared to primitive chondrites, which could reflect the accretion of a less oxygenated precursor by Ryugu. Possible effects of hydrothermal alteration and terrestrial weathering are also discussed. Last, no firm conclusions could be drawn about the origin of the soluble outlier phases, observed along with IOM in this study and in the preliminary analysis of Ryugu samples (Yabuta et al., 2023). However, it is crystal-clear that the HF/HCl residues presented in this publication are a mix between IOM and the nitrogen-rich outlier phase.
Keywords: spectroscopy, transmission, absorbance spectra, band position, mid-IR, organic matter, IOM, asteroid surface, Ryugu, Hayabusa2
Content: spectral data, planetary sciences