The rotation of Mimas

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

Titan's rotation: A 3-degree of freedom theory

International audienc

The rotation of Io predicted by the Poincar\'e-Hough model

This note tackles the problem of the rotation of Io with the 4-degrees of freedom Poincar\'e-Hough model. Io is modeled as a 2-layer body, i.e. a triaxial fluid core and a rigid outer layer. We show that the longitudinal librations should have an amplitude of about 30 arcseconds, independent of the composition of the core. We also estimate the tidal instability of the core, and show that should be slowly unstable.Comment: arXiv admin note: text overlap with arXiv:1111.301

A secondary resonance in Mercury's rotation

International audienceThe resonant rotation of Mercury can be modelised by a kernel model on which we can add perturbations. Our kernel model is a two-degree of freedom one written in Hamiltonian formalism. For this kernel, we consider that Mercury is solid and rotates on a Keplerian orbit. By introducing the perturbations due to the other planets of the Solar System, it appears that, in a particular case, our slow degree of freedom may enter into a 1:1 resonance with the Great Inequality of Jupiter and Saturn. Actually, as the moments of inertia of Mercury are still poorly known, this phenomenon cannot be excluded