N-bearing complex organic molecules in comet 67P

In terrestrial, carbon-based biochemistry, heteroelements such as oxygen, nitrogen, sulfur, and phosphorus play crucial roles as they introduce specific chemical functionalities in organic (hydrocarbon-based) molecules. The debate about the origin and evolution of life on Earth and possibly elsewhere requires a detailed understanding of (1) where and how organic chemical complexity emerges in space and (2) what exogenous materials may have been delivered to the early Earth through impacts, see, e.g., Rubin et al. (2019). Comet studies enable investigation of both aspects as these small bodies possess an organic-rich material record dating back to the earliest history of our Solar System and were an exogeneous contributor of volatile species to Earth (Marty et al. 2017).ESAs Rosetta mission visited and accompanied comet 67P/Churyumov-Gerasimenko (hereafter 67P) for two years and during a large part of the comets orbit around the Sun. Rosetta analyzed the comets chemical composition in unprecedented detail. A key instrument was the high-resolution Double Focusing Mass Spectrometer (DFMS) part of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA; Balsiger et al. 2007). It unveiled a surprising organic chemical complexity: Relying on reference spectra, either calibrated or from the database of the National Institute of Standards and Technology, Hnni et al. (2022) showed how the extremely complex cometary mass spectrum is fully deconvolved. After detailed investigation of the pure hydrocarbon species (Hnni et al. 2022) and the O-bearing organic molecules (Hnni et al. 2023), our current work focuses on the N-bearing compounds. The heteroelement N is common in biomolecules such as amino acids and nucleobases and responsible for their characteristic biochemical functionality. To date, only a few N-bearing complex organic molecules have been identified in comets, one of them being the simplest amino acid glycine (C2H5NO2), which was reported by Altwegg et al. (2016) after a targeted search. Here, we present a non-targeted, full analysis of the N- and NO-bearing complex organics and compare them to N-bearing molecules in meteorites, other comets, and the interstellar medium.Rubin et al. ACS Earth Space Chem. (2019) 3, 17921811.Marti et al. Science (2017) 356, 6342, 1069-1072.Balsiger et al. Space Sci. Rev. (2007) 128, 745-801.Hnni et al. Nat. Commun. (2022) 13, 3639.Hnni et al. Astron. Astroph. (2023) 678, A22.Altwegg et al. Science adv. (2016) 2, e1600285.