Titan Gravity and Tides from Cassini Tracking Data

Activity: Talk or presentationTalk or presentation at a conference


Knowledge of the internal structure of ocean worlds is important, in order to characterize the sub-surface ocean and its state. The gravity field of a body depends on its internal density distribution, and measurements of this quantity, together with measurements of its response to tidal forcing in the form of solid body tides, as expressed in the degree 2 potential Love number k2, can thus help constrain models of its interior. Previous analysis of Cassini tracking data has resulted in a gravity field model up to spherical harmonic degree 5, and a measurement for k2. Analysis of the gravity data collected at Titan indicated several possibilities for its interior structure: a partially differentiated interior, i.e., a mix of rock and ice, or a fully differentiated interior consisting of an icy shell over a low-density core. This previous measurement of k2 strongly suggests the presence of a sub-surface ocean.

Here, we present an analysis of Cassini tracking data, independent from previous efforts. We use NASA Goddard Space Flight Center’s GEODYN orbit determination and geodetic parameter estimation software to process the Cassini tracking data for twelve Titan flybys. Starting with only knowledge of the moon’s gravitational parameter in our analysis (i.e., setting all gravity coefficients’ start values to zero), we have determined a gravity field of degree and order 5 in spherical harmonics. In addition, we estimated Titan’s Love number k2. Our gravity and k2 results are close to previous results, independently confirming them, thus increasing confidence in the current knowledge of Titan’s interior structure
Period15 Dec 2020
Event titleAGU Fall Meeting 2020
Event typeConference
Degree of RecognitionInternational