Nitrogen- and nitrogen-oxygen-bearing organic molecules in comet 67P/Churyumov-Gerasimenko: An untargeted investigation
Year: 2025
Type: article
Abstract: Comets provide a unique window into the history of the Solar System as they carry some of the best-preserved material and make it available to in situ exploration. A milestone in comet studies was the European Space Agency’s Rosetta mission, which, for the first time, rendezvoused with a comet, namely 67P/Churyumov-Gerasimenko (67P), and studied it from a close range for two years. Amongst other unexpected insights, data from this mission show that comets contain a surprisingly large portion of organics, both in the refractory and the icy phases. For this work, we evaluated high-resolution mass spectra collected in comet 67P’s inner coma by Rosetta’s ROSINA-Double Focusing Mass Spectrometer (DFMS). In unprecedented detail, we investigated the N- and NO-bearing cometary complex organic molecules (COMs) of the general sum formula CnHmN and CnHmNO, where n and m are the stoichiometric coefficients of carbon and hydrogen. Our discussion-driven approach combines the empirical concept of Occam’s razor with knowledge from studies of relevant astrophysical environments and constraints expected from naive bottom-up assembly of molecules. We present an exemplary minimal and non-unique set of molecules needed to explain the DFMS observations. While this set might not capture the full organic diversity, but rather its lower limit, it identifies many N- and NO-bearing COMs with reasonable certainty, while excluding others, potentially informing future observational campaigns, and hence contributes to the exploration of the origin and evolution of organic complexity in space. Among the key results is strong evidence for an abundant presence of heterocycles as well as substantial alkylation of both cyclic and acyclic species. These findings align well with reports on soluble organic matter in meteorites and asteroids and underpin once more the potential importance of such extraterrestrial organic material as a feedstock for terrestrial prebiotic chemistry.
Source: Astronomy and Astrophysics
Authors: N. Hänni, K. Altwegg, D. Baklouti, M. Combi, S. A. Fuselier, J. De Keyser, D. R. Müller, M. Rubin, S. F. Wampfler
Language: English
Topic: Astro and Planetary Science
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
Awards: THE ROSETTA MISSION ACCOMPLISHED AN UNPRECEDENTED AND SUCCESSFUL 2-YEAR STUDY OF COMET 67P/CHURYUMOV-GERASIMENKO AS IT ORBITED THE SUN BEGINNING AT ~3.8 AU BEFORE PERIHELION FOLLOWING IT THROUGH ITS ACTIVE PERIOD AROUND PERIHELION AT 1.24 AU AND THEN OUT AGAIN AFTER PERIHELION AT ~3.8 AU. WHILE MANY THINGS HAVE BEEN LEARNED BY THE FIRST ROUND OF ANALYSES OF THE MEASUREMENTS OBTAINED MUCH IS LEFT TO BE INVESTIGATED IN THE VAST WEALTH OF DATA OBTAINED AND ARCHIVED. WE DEVELOPED A SPHERICAL HARMONICS INVERSION METHOD THAT WAS ORIGINALLY APPLIED TO ROSINA DFMS MASS SPECTROMETER MEASUREMENTS TO OBTAIN POTENTIAL SURFACE ACTIVITY MAPS OF H2O CO2 CO AND O2 ON THE NUCLEUS OF COMET 67P (FOUGERE ET AL. 2016A&B) AVERAGED OVER LARGE TIME SLICES OF THE MISSION. WE DEMONSTRATED SOME SUCCESS IN SYNTHESIZING VIRTIS-M SPECTRAL IMAGES AND VIRTIS-H SPECTRA OF H2O AND CO2 DENSITIES USING THE SURFACE POTENTIAL DISTRIBUTION DERIVED FROM IN SITU MASS SPECTROMETER MEASUREMENTS ALONG WITH OUR FULLY-KINETIC ADAPTIVE MESH PARTICLE SIMULATOR (AMPS) MODEL FOR THE COMA THAT USES THE TECHNIQUE CALLED DIRECT SIMULATION MONTE CARLO. WE HAVE SINCE ADAPTED THE INVERSION METHOD TO INGEST COLUMN DENSITY MAPS AND VALUES FROM IMAGING DATA RATHER THAN IN SITU DENSITY MEASUREMENTS AND ARE ABLE TO DERIVE POTENTIAL SURFACE ACTIVITY MAPS. HERE WE PROPOSE TO ANALYZE A SIGNIFICANT FRACTION OF H2O AND CO2 DISTRIBUTIONS DERIVED FROM VIRTISM SPECTRAL IMAGES AND VIRTIS-H SPECTRA USING SPHERICAL HARMONICS INVERSION SCHEME. THE ONE ADVANTAGE OF VIRTIS REMOTE SENSING MAPS OVER DFMS DENSITIES IS THAT REMOTE SENSING MEASURES THE DISTRIBUTION OF GAS IN COMA VERY CLOSE TO THE NUCLEUS AT KILOMETER AND SUB-KILOMETER SCALES WHEREAS THE MASS SPECTROMETER MEASURES THE DISTRIBUTION OF GAS FAR FROM THE NUCLEUS (10-400 KM) WHERE DETAILED INFORMATION OF THE DISTRIBUTION OF THE SOURCE REGION AT THE NUCLEUS HAS BEEN SMEARED OUT. OUR MAJOR SCIENTIFIC GOALS ARE (1) TO DETERMINE THE POTENTIAL SURFACE ACTIVITY DISTRIBUTIONS OF H2O AND CO2 FROM THE NUCLEUS AT MUCH HIGHER SPATIAL RESOLUTION THAN POSSIBLE FROM MASS SPECTROMETER MEASUREMENTS (2) TO DETERMINE THE CHANGE IN SURFACE ACTIVITY DISTRIBUTION OF H2O AND CO2 AS A FUNCTION OF TIME OVER THE MISSION (3) TO INVESTIGATE THE APPARENT INCONSISTENCY OF WATER ABUNDANCES DURING THE FEW MONTHS AROUND PERIHELION IN MID-2015 BETWEEN MASS SPECTROMETER AND REMOTE SENSING INSTRUMENTS AS CONTRASTED WITH THE CONSISTENCY DURING THE FIRST ONE-THIRD OF THE MISSION FROM RENDEZVOUS THROUGH THE FIRST EQUINOX (4) TO CORRELATE THE DISTRIBUTIONS OF THESE MAJOR VOLATILE COMPONENTS WITH THE MORE STRUCTURED DISTRIBUTIONS OF DUST PRODUCTION AS SEEN IN OSIRIS IMAGES. ALL OF THE DATA FROM VIRTIS AND OSIRIS REQUIRED FOR THIS INVESTIGATION IS ALREADY ARCHIVED IN THE SMALL BODIES NODE OF THE PLANETARY DATA SYSTEM THUS MAKING THIS STUDY APPROPRIATE FOR THE ROSETTA DATA ANALYSIS PROGRAM. THE TEAM INCLUDES INVESTIGATORS AND COLLABORATORS WITH ALL OF THE NECESSARY EXPERTISE INCLUDING ANALYSIS ANALYSIS TOOLS FOR THE DATA IN QUESTION CALIBRATION OF THE DATA AND AN INTIMATE KNOWLEDGE OF ALL THE NECESSARY DETAILS. ANALYSIS TOOLS INCLUDE THE SPHERICAL HARMONICS INVERSION METHOD AND THE AMPS COMET COMA MODEL. TEAM MEMBERS ARE THE EXPERTS IN THE DETAILS OF BOTH THE VIRTIS-M AND VIRTIS-H CHANNELS. WE HAVE EXPERIENCE IN RETRIEVING AND USING OSIRIS IMAGES FROM THE PDS., Neutral gas mass spectrometry in cometary comae – ESA’s Rosetta and Comet Interceptor missions, G8146203579
OpenAlex ID: W4411122305