First Steps Toward an Accurate Quantification of the Saturnian Tidal Dissipation

Tidal dissipation inside gaseous planets is crucial for the study of their long term evolution. For the exo-planets tidal dissipation has often been estimated from the Solar system giant planets. The tidal dissipation inside Saturn and Jupiter can be determined from theoretical assumptions on the orbital evolution of their satellites. This provides a lower bound for their dissipation parameter Q. On the other hand, past studies to seek tidal accelerations in the astrometrical residuals of the Galilean and Saturnian satellites resulted in large differences. We have started to investigate the possibility of quantifying more accurately the Saturnian dissipation from its influence on the satellite dynamics. The key point of our method stands in the introduction of the tidal dissipation directly during the fitting procedure to the astrometrical observations, (jointly with the initial orbital elements of each satellite). An extensive set of observations covering the years [1886-2007] was considered. Preliminary results are discussed.