The transition from soluble to insoluble organic matter in interstellar ice analogs and meteorites

¹ Aix-Marseille University, CNRS, Institut Origines, PIIM, Marseille, France
e-mail: gregoire.danger@univ-amu.fr
² Aix Marseille Université, Laboratoire d’Astrophysique de Marseille, UMR 7326, CNRS, CNES, Marseille, France
³ Institut Universitaire de France (IUF) Paris, France
⁴ Ludwig-Maximilians-University, Department of Chemistry and Pharmacy, Butenandtstr. 5-13, 81377 Munich, Germany and Excellence Cluster ORIGINS, Boltzmannstraße 2, 85748 Garching, Germany
e-mail: alexander.ruf@cup.uni-muenchen.de
⁵ Normandie Univ., COBRA UMR 6014 et FR 3038 Univ. Rouen; INSA Rouen; CNRS IRCOF, 1 Rue Tesnière, 76821 Mont-Saint-Aignan Cedex, France
⁶ Muséum National d’Histoire Naturelle, Sorbonne Université, UMR CNRS 7590, Institut de minéralogie, de physique des matériaux et de cosmochimie, Paris, France
⁷ Université de Haute-Alsace, ENSCMu, Lab. GSEC, 3 Rue Alfred Werner, 68093 Mulhouse Cedex, France
⁸ Helmholtz Zentrum München, Analytical BioGeoChemistry, Neuherberg, Germany
⁹ Technische Universität München, Chair of Analytical Food Chemistry, Freising-Weihenstephan, Germany

Received: 5 June 2022
Accepted: 1 August 2022

Abstract

Context. Carbonaceous chondrites are sources of information on the origin of the Solar System. Their organic content is conventionally classified as soluble (SOM) and insoluble organic matter (IOM), where the latter represents the majority.

Aims. In this work, our objectives are to identify possible relations between soluble and insoluble organic matter generated in laboratory experiments and to extrapolate the laboratory analog findings to soluble and insoluble organic matter of meteorites to test their connection.

Methods. Using laboratory experiments, processes possibly linking IOM analog (IOMA) to SOM analog (SOMA) precursors are investigated by assuming that dense molecular ices are one of the sources of organic matter in the Solar System. Each organic fraction is analyzed by laser desorption coupled to a Fourier transform ion cyclotron resonance mass spectrometer on a comprehensive basis.

Results. SOMA and IOMA significantly differ in their chemical fingerprints, and particularly in their aromaticity, O/C, and N/C elemental ratios. Using an innovative molecular network, the SOMA–IOMA transition was tested, revealing connection between both classes. This new network suggests that IOMA is formed in two steps: a first generation IOMA based on precursors from SOMA, while a second IOMA generation is formed by altering the first IOMA generation. Finally, using the same analytical technique, the molecular content of IOMA and that of the Paris IOM are compared, showing their molecular similarities for the first time. The molecular network application to the Paris SOM and IOM demonstrates that a possible connection related to photochemical ice processing is present, but that the overall history of IOM formation in meteorites is much more complex and might have been affected by additional factors (e.g., aqueous alteration).

Conclusions. Our approach provides a new way to analyze the organic fraction of extraterrestrial material, giving new insights into the evolution of organic matter in the Solar System.