Comets and Asteroids

Complex Organosulfur Molecules On Comet 67P: Evidence From The ROSINA Measurements And Insights From Laboratory Simulations

By Keith Cowing

Status Report

Caltech

July 1, 2023

Filed under astrochemistry, Caltech, Comet, Comet 67P/Churyumov-Gerasimenko, JWST, organic chemistry, Rosetta, ROSINA, spectrometer

Complex Organosulfur Molecules On Comet 67P: Evidence From The ROSINA Measurements And Insights From Laboratory Simulations — Sulfur-bearing species detected by ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis)–DFMS (Double Focusing Mass Spectrometer) before and during the dust event on 5 September 2016, ~2 km above the nucleus surface. 17:xx denotes measurements made before the dust impact between 17:15 and 17:55 UTC (depending on mass), and 18:xx denotes measurements during the dust impact (18:09 to 18:50). (A) CnHmSl bearing species, n = 0 to 4; m = 0 to 6, l = 1 to 2. (B) CnHmOlS- and CHnNS-bearing species, n = 0 to 3; m = 0 to 6, l = 1 to 2. Species are ordered by mass/charge ratio (m/z) but not spaced accordingly (x axis not linear). The value, pre-event, for SO could not be derived as the spectrum is corrupted. Abundances are given in arbitrary units (a.u.) but corrected for instrumental effects (mass-dependent sensitivity). Caution: During the impact, coma background densities decreased over the 40 min needed to cover the mass range. Higher masses are therefore underestimated compared to low masses. – Caltech/Science Advances

The ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) instrument aboard the Rosetta mission revolutionized our understanding of cometary material composition. One of Rosetta’s key findings is the complexity of the composition of comet 67P/Churyumov-Gerasimenko.

Here, we used ROSINA data to analyze dust particles that were volatilized during a dust event in September 2016 and report the detection of large organosulfur species and an increase in the abundances of sulfurous species previously detected in the coma. Our data support the presence of complex sulfur-bearing organics on the surface of the comet.

In addition, we conducted laboratory simulations that show that this material may have formed from chemical reactions that were initiated by the irradiation of mixed ices containing H2S.

Our findings highlight the importance of sulfur chemistry in cometary and precometary materials and the possibility of characterizing organosulfur materials in other comets and small icy bodies using the James Webb Space Telescope.

Mahjoub, Ahmed and Altwegg, Kathrin and Poston, Michael J. and Rubin, Martin and Hodyss, Robert and Choukroun, Mathieu and Ehlmann, Bethany L. and Hänni, Nora and Brown, Michael E. and Blacksberg, Jordana and Eiler, John M. and Hand, Kevin P.

Complex organosulfur molecules on comet 67P: Evidence from the ROSINA measurements and insights from laboratory simulations, Caltech AUTHORS

Complex organosulfur molecules on comet 67P: Evidence from the ROSINA measurements and insights from laboratory simulations, Science advances (open access)

Astrobiology, Astrochemistry

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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