Presentation #403.11 in the session Into the Unknown: Astrobiology and Habitability.
Geophysical measurements can reveal the interior properties of icy ocean worlds. Such measurements can point to the presence and temporal variability of fluids, thus identifying potential habitable niches for life . The thickness and geodynamics of different ice phases and the depth of the ocean determine the conditions under which life might exist. The global fluxes of chemical energy must be understood in terms of a world’s interior structure and evolution. Such a global picture is necessary for quantifying the types of life and amounts of biomass that might be supported. Understanding habitability using geophysical measurements is expected to involve the joint inversion of gravitational, geodetic, and magnetic measurements, enabled by improvements in material properties and computational approaches to planetary modeling [e.g., 2].
The electrical properties of the ocean may be used to obtain clues to the ocean’s salinity, mainly through measurements of magnetic induction. Recent work demonstrates the potential for characterizing oceans in moons of the gaseous outer planets using magnetic induction [3,4,5], building on the detection of oceans in Europa and possibly Callisto by the Galileo mission [6,7]. Electrical conductivity varies strongly with temperature, pressure, and composition, and have not been adequately measured for conditions in ocean worlds—T from -40 to 100 °C; P up to 2 GPa (20 kbar). Experiments are underway to improve the available data pertaining to electrical conductivity of ocean worlds, addressing gaps that currently limit the ability to characterize ocean composition. Recent measurements in aqueous MgSO4 and NaCl extend to the highest pressures occurring in the hydrosphere of the largest ocean moon, Ganymede [8,9], and improve the coverage at low temperature and high concentration.
We will review recent progress on geophysical investigations of ocean world interiors, with a focus on electrical data, including the development of new experiments to measure electrical conductivity under relevant conditions.
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