We are pleased to announce the speaker for the 2023 Peale Lecture is Katherine deKleer.

Katherine is an Assistant Professor of Planetary Science and Astronomy at Caltech. She is interested in dynamic planetary processes and how they relate to the surface environments, atmospheres, and thermochemical histories of planets and satellites. Her research focuses on characterizing these processes through the application of statistical methods to telescope observations at optical through radio wavelengths. Her work to date has focused on topics including the atmospheric composition and global circulation of Uranus, Neptune, and Jupiter; the volcanism, atmosphere, and tidal heating of Io; and the sub-surface material properties of Europa, Callisto, and Ganymede. 

The 2023 Peale Lecture will take place Tuesday November 28^th at 3:30pm in the KITP Main Auditorium.

The history of tidal heating at the galilean moons

The galilean moons Io, Europa, and Ganymede are internally heated by tides arising from their 4:2:1 LaPlace orbital resonance. The resultant volcanic activity at Io – first predicted by Peale, Cassen & Reynolds (1979) – provides directly-observable signatures by which we can study the influence of tides on the interior of planetary-scale bodies. This talk will present telescopic observations of Io’s volcanic gasses and lava flows, which we use to derive statistical properties that constrain tidal heating models for Io’s interior. Such observations provide important clues into Io’s current state. However, Io’s activity rapidly erases any indicators of its history prior to the most recent million years. As a consequence, the history of Io’s volcanism, and of the LaPlace resonance between the galilean moons, remains unknown. In 2002, Peale & Lee proposed that the LaPlace resonance is primordial, a finding that is also supported by current numerical modeling. I will present a new study in which we used millimeter spectroscopy from the Atacama Large (sub-)Millimeter Array to derive the isotopic ratios of sulfur and chlorine in Io’s atmosphere. The isotopic ratios hold a record of Io’s volcanic activity over the age of the Solar System, shedding light on past tidal heating at Io and hence the age of the LaPlace resonance between the moons.