![]() < p> Cassini& #8217 s Grand Finale orbits brought us historical first in-situ measurements of Saturn& #8217 s ionosphere, showing that it contains dusty plasma in the equatorial region. Morooka M, Dougherty M, Wahlund J-E, Hunt G, Waite H, Müller-Wodarg I et al., 2021, The conductive dusty ionosphere of Saturn We will discuss future directions of development towards the construction of the new model capable of resolving the complex ring-atmosphere coupling and electrodynamics, and the possibility of adapting this model to other planets.< /div> < /div> < /div> < /div> We will present initial results having adapted SAMI to Saturn, showing the full extent of the atmospheric chemistry and model capabilities at present. Thus, we adapt SAMI, a well-known terrestrial ionosphere model that is flux-tube based and already includes electrodynamics, to Saturn, with the aim of using it in conjunction with existing Saturn models such as the STIM-GCM (Saturn Thermosphere Ionosphere Model) to decipher the long-standing unexplained morphologies in Saturn& #8217 s ionosphere and investigate the ring-atmosphere coupling and electrodynamics revealed by the Cassini end-of-mission data. Current Saturn models are ill-suited to treating electrodynamics and ring-planet interactions at Saturn. In-situ observations reveal highly complex coupling between the planetary atmosphere and rings and inter-hemispheric electrodynamic coupling at latitudes that are magnetically connected to the intra D-ring region in the magnetosphere. < div> < div> < div> < div> The Cassini Grand Finale revealed that there is still much that we do not understand about Saturn& #8217 s upper atmosphere. ![]() Mueller-Wodarg I, Huba J et al., 2022, First Steps Towards a New Saturn Ionosphere Model Including Ring-Planet Coupling and Electrodynamics 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. 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. 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 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. ![]() 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. ![]() Fletcher LN, Serigano J, Guerlet S, Moore L, Waite JH, Ben-Jaffel L, Galand M, Chadney JM, Hörst SM, Sinclair JA, Vuitton V, Müller-Wodarg I et al., 2023, Saturn’s atmospheric response to the large influx of ring material inferred from Cassini INMS measurements, Icarus, Vol: 391, Pages: 1-40, ISSN: 0019-1035ĭuring 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.
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