Compositional Measurements of Saturn’s Upper Atmosphere and Rings from Cassini INMS: An Extended Analysis of Measurements from Cassini’s Grand Finale Orbits

J. Serigano (1) , S. M. Hörst (1) , C. He (1) , Thomas Gautier (2) , R. V. Yelle (3) , T. T. Koskinen (3) , M. G. Trainer (4) , M. J. Radke (1)

1 Morton K. Blaustein Department of Earth and Planetary Sciences [Baltimore]
2 PLANETO - LATMOS
3 LPL - Lunar and Planetary Laboratory [Tucson]
4 GSFC - NASA Goddard Space Flight Center

The Cassini spacecraft’s final orbits sampled Saturn’s atmosphere and returned surprisingly complex mass spectra from the Ion and Neutral Mass Spectrometer (INMS). Signal returned from the instrument included native Saturn species, as expected, as well as a significant amount of signal attributed to vaporized ices and higher mass organics believed to be flowing into Saturn’s atmosphere from the rings. In this paper, we present an in-depth compositional analysis of the mass spectra returned from Cassini’s last few orbits. We use a mass spectral deconvolution algorithm designed specifically to handle the complexities involved with unit resolution spaceflight mass spectrometry data to determine the relative abundance of species detected in the observations. We calculate the downward external flux and mass deposition rates of ring volatile species into Saturn’s atmosphere and conclude that during these observations ring material was being deposited into Saturn’s equatorial region at a rate on the order of 10⁴ kg/s.

Mots clés: Saturrn; Rings; Cassini; Mass Spectrometry; Planetary Atmosphere

Domaines: Planète et Univers [physics]

J. Serigano, S. M. Hörst, C. He, Thomas Gautier, R. V. Yelle, et al.. Compositional Measurements of Saturn’s Upper Atmosphere and Rings from Cassini INMS: An Extended Analysis of Measurements from Cassini’s Grand Finale Orbits. Journal of Geophysical Research. Planets, 2022, 127 (6), pp.e2022JE007238. ⟨10.1029/2022JE007238⟩. ⟨insu-03670148⟩