[S19-1] Giant planet and remote sensing seismology, Europa and ocean-world seismology

[S19-1-05] Seismic Exploration of Europa and Other Ocean Worlds

^○Steven Vance¹, Sharon Kedar¹, Sridhar Anandakrishnan², Bruce Banderdt¹, Bruce Bills¹, Fabio Cammarano³, Julie Castillo¹, Hsin-Hua Huang^4,5, Jennifer Jackson⁴, Philippe Lognonne⁶, Ralph Lorenz⁷, Mark Panning⁸, William Pike⁹, Simon Staehler¹⁰, Victor Tsai⁴ (1.Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, United States, 2.Pennsylvania State University Main Campus, University Park, PA, United States, 3.U. Roma Tre, Rome, Italy, 4.California Institute of Technology, Pasadena, CA, United States, 5.Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan, 6.Institut de Physique du Globe de Paris, Paris, France, 7.Johns Hopkins University Applied Physics Laboratory, Laurel, MD, United States, 8.Univ of FL-Geological Sciences, Gainesville, FL, United States, 9.Imperial College London, London, SW7, United Kingdom, 10.Ludwig Maximilians University of Munich, Germany)

invited

Seismic investigations offer a view into the deep interiors of planetary bodies and thus into the processes governing their habitability. The InSight mission and concepts for a Europa Lander and a Lunar Geophysical Network present unique opportunities for seismology to play a critical role in constraining interior structure and thermal state. In oceanic icy worlds, measuring the radial depths of compositional interfaces using seismology in a broad frequency range can sharpen inferences of interior structures deduced from gravity and magnetometry studies, such as those planned for NASA's proposed Europa Mission and ESA's JUICE mission. Seismology may also provide information about fluid motions within or beneath ice, which complements magnetic studies; and can record the dynamics of ice layers, which would reveal mechanisms and spatiotemporal occurrence of crack formation and propagation. Investigating these structures and processes in the future calls for detailed modeling of seismic sources and signatures, in order to develop the most suitable instrumentation.

We will present results of simulations of plausible seismic sources and wave-field propagation in Europa, with extension to other oceanic icy worlds, building on prior studies. We will also consider additional sources: gravitationally forced librations, which create volume-filling turbulent flow, a possible seismic source similar to that seen from turbulent flow in terrestrial rivers; downflow of dense brines from chaos regions on Europa into its underlying ocean, which possibly resemble riverine flows and flows through glacial channels and ocean acoustic signals that couple with the overlying ice to produce seismic waves, by analogy with Earth's ocean-generated seismic hum.