True Polar Wander of Enceladus From Topographic Data

Abstract

Many obsects in the solar system are suspected to have experience reorientation of their spin axes. As their rotation rates are slow and their shapes are nearly spherical, the formation of mass anomalies, by either endogenic of exogenic processes, can change objects' moments of inertia. Therefore, the objects reorient to align their largest moment of inertia with their spin axis. Such phenomenon is called True Polar Wander (TPW). Here we report the discovery of a global series of topographic lows on Saturn's satellite Enceladus that we interpret to show that this synchronously locked moon has undergone TPW by ~55° about the tidal axis. We use improved topographic data from the spherical harmonic expansion of Cassini limb and stereogrammetric measurements to characterize regional topography over the surface of Enceladus. We identify a group of nearly antipodal basins orthogonal to a topographic basin chain tracing a non-equatorial circumglobal belt across Enceladus' surface. We argue that the belt and the antipodal regions are fossil remnants of an earlier equator and poles, respectively. We argue that these lows arise from isostasic compensation and that their pattern reflects spatial variations in internal dynamics of the ice shell. Our hypothesis is consistent with a variety of geological features visible in Cassini images.

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Cited by in corpus (10)

• Enceladus's crust as a non-uniform thin shell: I Tidal deformations
• Spontaneous formation of geysers at only one pole on Enceladus' ice shell
• Different ice shell geometries on Europa and Enceladus due to their different sizes: impacts of ocean heat transport
• Probing the icy shell structure of ocean worlds with gravity-topography admittance
• The role of ocean circulation in driving hemispheric symmetry breaking of the ice shell of Enceladus
• The effect of salinity on ocean circulation and ice-ocean interaction on Enceladus
• Differing Enceladean ocean circulation and ice shell geometries driven by tidal heating in the ice versus the core
• True Polar Wander on Dynamic Planets: Approximative Methods vs. Full Solution
• Repeated Impact-Driven Plume Formation On Enceladus Over Megayear Timescales
• Dynamic reorientation of tidally locked bodies: application to Pluto