The ice shell on Enceladus, an icy moon of Saturn, exhibits strong asymmetry between the northern and southern hemispheres, with all geysers compacted over the south pole, even though the external configuration is almost perfectly symmetric.

Using an idealized thin ice model, we demostrate that this asymmetry may form spontaneously, without any noticeable a priori asymmetry (such as a giant impact or a monopole structure of geological activity), as opposed to previous studies. Infinitesimal amounts of hemispheric asymmetry in the ice shell thickness due to random perturbations are found to be able to grow indefinitely, ending up significantly thinning the ice shell at one of the poles relative to the other and thereby allowing the fracture formation there.

This proposed symmetry breaking is suggested to occur only on small planetary bodies with specific combinations of global mean thickness of the ice shell and surface temperature, consistent with current observations. This parameter regime, once it gets better constrained using more complex models, may be used to predict the ice shell structure on other planetary bodies.

Wanying Kang, Glenn Flierl

(Submitted on 29 Dec 2019)

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

Cite as: arXiv:1912.12554 [astro-ph.EP] (or arXiv:1912.12554v1 [astro-ph.EP] for this version)

Submission history

From: Wanying Kang

[v1] Sun, 29 Dec 2019 00:24:57 UTC (305 KB)

https://arxiv.org/abs/1912.12554

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