February 24, 2023

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Speaker: Ben Teolis, Planetary Scientist, Southwest Research Institute

Host: David Goldstein

Title: Gas Jets and Exospheric Dynamics at Active Icy Worlds

Abstract: The origin of Enceladus’s water vapor / ice plumes found by the Cassini spacecraft, beginning with transport, boiling, and acceleration of mixed phase fluid through the icy crust leading to ‘nozzle’-like gas jets, is a fundamental yet still relatively under-explored aspect of the physics of this active potentially habitable world. Problems including erosion and cavitation of uneven subsurface channels, dissolved CO2 and H2 bubbling out of solution and trapping in gas pockets within the fissures, and adsorption/sublimation of gas species to/from the fissure walls, are just a few considerations impacting future spacecraft exploration of the composition, structure and dynamics of the ejected jets. Beyond Enceladus, the Cassini spacecraft’s findings of exospheres with extreme seasonal dynamics and uneven structure, and of un-expectedly intense charging and field aligned electric currents at Saturn’s other large moons, have contributed to a transformative period in fundamental understanding of planetary systems. These discoveries have helped set the stage for the next stage of solar system exploration targeted at the highly seasonal Uranian system with its large moons, as well as the Galilean satellites including the potentially habitable moon Europa with its possible water vapor plumes. In this talk, I will discuss current understanding of the origins and inner workings of the plumes, exospheres and plasma interactions of Enceladus and other active worlds, and outstanding questions and possible next steps.

Biography: Dr. Teolis is a physicist, experimentalist, and planetary scientist, and an expert in planetary atmospheres and magnetospheres, as well as chemical and radiation processes on the surfaces of icy bodies in the outer solar system. He is a Co-Investigator for the MASPEX instrument on NASA’s Clipper mission to Jupiter’s moon Europa to investigate surface and atmospheric composition, and to search for possible plume-eruptions and habitable conditions. As a Cassini spacecraft scientist for over a decade, Dr. Teolis is a specialist on the Saturn system, its moons, and magnetosphere, including detailed observations and modeling of the strength and time variability of the gas jets comprising the plumes of the geologically active moon Enceladus. Dr. Teolis has authored/co-authored 50 scientific papers covering an expansive set of subjects, including planetary atmospheres and space plasmas, spacecraft instrumentation, optics and thin films, and chemical and radiation surface processing of icy planetary bodies.