12/mar/21 – Astrometry Unleashed: The Saturnian System (Dr. Valéry Lainey, Observatório de Paris/IMCCE)

During the thirteen years in orbit around Saturn before its final plunge, the Cassini spacecraft provided more than ten thousand astrometric observations of moons. Such a large number of accurate data enable the search for extremely small signals in the orbital motion of saturnian satellites. These signals can be related to key physical mechanisms at play in the system, opening the doors to a new vision of the Saturn system. Using more than a century of ground-based astrometric observations, and benefitting from Cassini’s imaging data, we have studied the orbital motion of all the inner and main moons of Saturn, including the recently discovered ones by the Cassini spacecraft. We show how astrometry has succeeded in characterizing the strong tidal effects inside the Saturn system, while assessing interior characteristics of the inner moons and their primary.