Saturn’s atmospheric response to the large influx of ring material inferred from Cassini INMS measurements
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Published version
Author(s)
Type
Journal Article
Abstract
During the Grand Finale stage of the Cassini mission, organic-rich ring material was discovered to be flowing into Saturn’s equatorial upper atmosphere at a surprisingly large rate. Through a series of photochemical models, we have examined the consequences of this ring material on the chemistry of Saturn’s neutral and ionized atmosphere. We find that if a substantial fraction of this material enters the atmosphere as vapor or becomes vaporized as the solid ring particles ablate upon atmospheric entry, then the ring-derived vapor would strongly affect the composition of Saturn’s ionosphere and neutral stratosphere. Our surveys of Cassini infrared and ultraviolet remote-sensing data from the final few years of the mission, however, reveal none of these predicted chemical consequences. We therefore conclude that either (1) the inferred ring influx represents an anomalous, transient situation that was triggered by some recent dynamical event in the ring system that occurred a few months to a few tens of years before the 2017 end of the Cassini mission, or (2) a large fraction of the incoming material must have been entering the atmosphere as small dust particles less than 100 nm in radius, rather than as vapor or as large particles that are likely to ablate. Future observations or upper limits for stratospheric neutral species such as HCN, HCN, and CO at infrared wavelengths could shed light on the origin, timing, magnitude, and nature of a possible vapor-rich ring-inflow event.
Date Issued
2023-02
Date Acceptance
2022-10-20
Citation
Icarus, 2023, 391, pp.1-40
ISSN
0019-1035
Publisher
Elsevier BV
Start Page
1
End Page
40
Journal / Book Title
Icarus
Volume
391
Copyright Statement
© 2022 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Identifier
https://www.sciencedirect.com/science/article/pii/S0019103522004201?via%3Dihub
Subjects
astro-ph.EP
astro-ph.EP
Astronomy & Astrophysics
0201 Astronomical and Space Sciences
0402 Geochemistry
0404 Geophysics
Publication Status
Published
Article Number
115328
Date Publish Online
2022-10-27