The Gravity of Titan: Analysis of Cassini's Doppler Tracking Data and Solar Radiation Pressure

Saturn's largest natural satellite, Titan, is an icy moon expected to harbour a liquid sub-surface water ocean capable of habiting extra-terrestrial life. The spherical harmonic expansion of the gravity field and the tidal Love number k2 can be used to estimate densities, depths, and phases of different layers from Titan’s interior structure, granting insight on the sub-surface ocean and its habitability. Recent research has determined the spherical harmonic expansion of the gravity field up to degree five including the estimation of Titan’s tidal Love number k2. This work estimates the spherical harmonic gravity field of Titan up to degree three through a multi-arc batch weighted least squares approach, with fundamental differences from previous research. We include observation biases and empirical accelerations for estimation in our dynamic force model and apply no constraints on the gravity and tidal parameters for estimation. Previous research claims the applied global constraints do not constrain the solution, yet an independent estimation of the gravity and tides of Titan yields significantly different results: high correlation between global parameters results in the inability to determine a realistic k2 Love number. We refrain from applying any global constraints to the gravity and tidal parameters, as there exists no a priori information on these parameters to apply a physical and unbiased constraint.Aerospace Engineerin