The origin and evolution of the Saturnian satellites is still debated. While the canonical formation model creates many main moons in Saturn's subnebulae, a new model suggests a possible formation at the outer edge of a past massive ring (Charnoz et al. 2011). Furthermore, many interior structure models were suggested for Enceladus in order to explain the geysers observed in its South polar region. For instance, Nimmo and Pappalardo (2006) suggest the existence of a low density anomaly in the ice crust, and Collins and Goodman (2007) explain these geysers by an internal local "sea" with higher density than the ice crust. It is also noteworthy that in the model of Charnoz et al. (2011), the core of the satellites is not necessarily symmetric, due to the accretion of icy material onto large silicate chunks (> 10 - 100 Km). All these previous models may result in a shift between the center of mass and the center of figure of the satellites. We used the astrometry of Cassini ISS NAC images of Mimas and Enceladus to attempt to quantify such a shift considering, on one hand, the satellite's observed position as the center of figure and, on the other hand, its predicted position from the orbital ephemeris as the center of mass. In studying such a shift, we may add new constraints to the existing models and possibly discriminate between the various interior and formation models of the Saturnian system.
AAS/Division for Planetary Sciences Meeting Abstracts #44
- Pub Date:
- October 2012