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DIX Planetary Science Seminar

Tuesday, February 4, 2025
4:00pm to 5:00pm
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Arms 155 (Robert P. Sharp Lecture Hall)
Unveiling Callisto's Atmosphere: Insights from Past Observations, Future Mission Perspectives, and Implications for Europa and Ganymede
Shane Carberry Mogan, Postdoctoral Scholar, University of California, Berkeley,

Callisto, Jupiter's outermost Galilean satellite, hosts a tenuous atmosphere whose evolution is driven by solar illumination and jovian magnetospheric bombardment of its icy surface. By integrating theoretical models with observational data, this presentation explores the origins, composition, and dynamics of Callisto's atmosphere, linking past findings to future observations and their implications for Europa and Ganymede. Recent studies reveal that the atomic hydrogen corona observed by Hubble is primarily sourced by radiolytically produced H2, prompting a reevaluation of the role of sublimated water vapor, the originally inferred dominant source of H. However, investigations into the O2 produced via radiolysis alongside H2 suggest that this source cannot account for the atmospheric abundances inferred from in-situ and remote observations, highlighting the need for a reevaluation of generation mechanisms and better constraints on loss processes. These discrepancies underscore the importance of further studying interactions between Callisto's plasma environment, surface, and atmosphere. Future observations from Hubble, JUICE, and Europa Clipper will be pivotal in refining these models and advancing our understanding of icy satellite atmospheres.

For more information, please contact YuYu Phua by email at yphua@caltech.edu.