Ref: POSTER-2021-0008

Cassini state of Galilean Moons: Influence of a subsurface ocean

Coyette, Alexis ; Baland, Rose-Marie ; Lemaitre, Anne ; Van Hoolst, Tim

Poster presented at 22nd EGU General Assembly, held online on 2020-05-04

Abstract: Large moons such as the Galilean satellites are thought to be in an equilibrium rotation state, called a Cassini state (Peale, 1969). This state is characterized by a synchronous rotation and a precession rate of the rotation axis that is equal to the precession rate of the normal to its orbit. It also implies that the spin axis, the normal to the orbit and the normal to the Laplace plane are coplanar with a (nearly) constant obliquity. For rigid bodies, up to 4 possible Cassini states exist, but not all of them are stable. It is generally assumed that the Galilean satellites are in Cassini State I for which the obliquity is close to zero (see e.g. Baland et al. 2012). However, it is also theoretically possible that these satellites occupy or occupied another Cassini state. We here investigate how the interior structure, and in particular the presence of a subsurface ocean, influences the existence and stability of the different possible Cassini states.

Keyword(s): Cassini state ; Galilean satellites
Links: link
Funding: Prodex/Prodex/Prodex

The record appears in these collections:
Royal Observatory of Belgium > Reference Systems & Planetology
Conference Contributions & Seminars > Posters

 Record created 2021-01-25, last modified 2021-01-25

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