Detectability Of Local Water Reservoirs In Europa’s Surface Layer Under Consideration Of Coupled Induction

By Keith Cowing
Status Report
October 10, 2023
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Detectability Of Local Water Reservoirs In Europa’s Surface Layer Under Consideration Of Coupled Induction
Magnetic field components in the xy-plane in the ocean-reservoir environment after mutual induction coupling for a reservoir with radius rres = 20 km and finite conductivity σres = 30 S/m, where the induction response of the system follows equation 19. The arrows representing the magnetic field are normalized in length and do not represent the strength of the magnetic field, which is instead color coded in the background. The arrows in the center indicate the orientations of the background field (black), ocean induced field (green), and reservoir induced field (cyan), where the length indicates the strength relative to the background field. The dashed black line visualizes the surface boundary. — astro-ph.EP

The icy moon Europa is a primary target for the study of ocean worlds. Its subsurface ocean is expected to be subject to asymmetries on global scales (tidal deformation) and local scales (chaos regions, fractures).

Here, we investigate the possibility to magnetic sound local asymmetries by calculating the induced magnetic fields generated by a radially symmetric ocean and a small, spherical water reservoir between the ocean and Europa’s surface. The consideration of two conductive bodies introduces non-linear magnetic field coupling between them.

We construct an analytical model to describe the coupling between two conductive bodies and calculate the induced fields within the parameter space of possible conductivity values and icy crust thicknesses. Given the plasma magnetic field perturbations, we find that a reservoir cannot be detected during a flyby at 25 km altitude using electromagnetic induction.

Potential detection of liquid water reservoirs can be achieved by deploying magnetometers on Europa’s surface, where one magnetometer is placed directly on the target region of interest and a second one in the nearby vicinity as reference to distinguish from global asymmetries. With this method, the smallest reservoir that can be detected has a radius of 8 km and a conductivity of 30 S/m. Larger reservoirs are resolvable at lower conductivities, with a 20 km reservoir requiring a conductivity of approximately 5 S/m.

J. Winkenstern, J. Saur

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2309.07674 [astro-ph.EP] (or arXiv:2309.07674v1 [astro-ph.EP] for this version)
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Submission history
From: Jason Winkenstern [view email]
[v1] Thu, 14 Sep 2023 12:36:51 UTC (588 KB)

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