The rotation of Mimas

TL;DR

This study models Mimas's rotation considering various internal structures, using Cassini data and numerical simulations, to identify observable signatures of its internal composition and estimate its rotational deviations.

Contribution

It introduces a detailed rotational model of Mimas with layered interior structures and simulates their effects on observable rotational signatures.

Findings

Longitudinal librations up to 0.53° could reveal internal structure

Estimated obliquity between 2 and 3 arcmin depends on interior composition

Detectability of librations presents observational challenges

Abstract

The Cassini mission in the Saturnian system is an outstanding opportunity to improve our knowledge of the satellites of Saturn. The data obtained thanks to this mission must be confronted to theoretical models. This paper aims at modeling the rotation of Mimas, with respect to its possible internal structure. For that, we first build different interior models, in considering Mimas as composed of 2 rigid layers with different porosity. Then we simulate the rotational behavior of these models in a 3-degree of freedom numerical code, in considering complete ephemerides of a Mimas whose rotation is disturbed by Saturn. We also estimate the deviation of its longitudinal orientation due to tides. We expect a signature of the internal structure up to 0.53{\deg} in the longitudinal librations and an obliquity between 2 and 3 arcmin, the exact values depending on the interior. The longitudinal librations should be detectable, inverting them to get clues on the internal structure of Mimas is challenging.