- Thu Apr 9 (room reservation 14:00 JST [=UTC+09:00]), ELSI-1 105 Mishima Hall [Seminar] Special Seminar - Catherine Psarakis (UCLA) - From Molecules to Magnetic Fields Seminar Open to ALL of ELSI Seminar Title: From Molecules to Magnetic Fields: Constraining the Interior Structure and Composition of Europa and Ganymede through Molecular Dynamics and Electromagnetic Induction Time 2 pm - 3 pm. Abstract: The subsurface oceans of Europa and Ganymede are prime targets in the search for habitable environments beyond Earth, yet their composition and interior structure remain poorly constrained. Electromagnetic induction can directly probe the interiors of these moons without landing, but its interpretation is fundamentally limited by degeneracy: multiple interior configurations can produce nearly identical magnetic signatures. Here, I present a framework that links molecular scale fluid properties to spacecraft observable magnetic fields, enabling a physically grounded assessment of which interior properties are magnetically distinguishable. At the smallest scale, molecular dynamics simulations are used to derive pressure, temperature, and composition-dependent electrical conductivity relationships for analog fluids, providing realistic conductivity profiles for icy moon interiors. These are incorporated into an interior modeling pipeline constrained by mass and moment of inertia, generating layered conductivity structures for Europa and Ganymede. Forward electromagnetic induction models are then used to quantify how variations in ocean conductivity and thickness, as well as deeper interior structure, affect the induced magnetic field. Results show that for Ganymede, ocean conductivities above ~0.6 S/m saturate the induction response at the synodic period, rendering deeper structure magnetically invisible, while lower conductivity oceans permit partial sensitivity to mantle and core properties. Similarly, for Europa, realistic ocean conductivities strongly shield the mantle, limiting the detectability of deep interior structure by Europa Clipper. These results highlight both the power and limitations of magnetic induction, emphasizing the importance of multi-frequency measurements. Looking ahead, upcoming observations from the JUICE mission will provide broadband magnetic spectra that will penetrate beyond the ocean and potentially resolve deeper interior structure. This work establishes a framework for interpreting these measurements and for connecting ocean chemistry, interior structure, and habitability in icy ocean worlds. Bio Catherine Psarakis is a PhD candidate in Geochemistry at the University of California, Los Angeles working with Dr. Abby Kavner and Dr. Krishan Khurana. As a NASA FINESST Fellow, Catherine’s research focuses on the electrical conductivity and interior structure of icy ocean worlds, with an emphasis on magnetic induction modeling to constrain subsurface oceans on Ganymede and Europa. Her dissertation develops a framework that links ocean composition and interior structure to spacecraft-observable magnetic signals, integrating constraints from geophysics, geochemistry, and computational modeling. Catherine has conducted prior experimental and computational work at NASA Jet Propulsion Laboratory on the electrical conductivity of aqueous systems relevant to planetary interiors. She has presented her research at major conferences including the Lunar and Planetary Science Conference, the American Geophysical Union Fall Meeting, and the Division for Planetary Sciences Meeting, and her work has been published in ACS Earth and Space Chemistry. She is also an AAUS certified scientific diver, reflecting her broader interest in ocean exploration and analog environments. Host: Mohit Melwani Daswani - Thu Apr 9 (room reservation 15:00 JST [=UTC+09:00]), ELSI-1 105 Mishima Hall [Seminar] Seminar - Kevin Rosso Kevin Rosso Pacific Northwest National Laboratory Washington, USA Title: Redox Reactions of Iron in Clay Minerals with Environmental Contaminants - Fri Apr 10 (room reservation 14:00 JST [=UTC+09:00]), ELSI-1 207 Seminar Room B [Study Group] Metabolism Hour