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W.B. Moore, G. Schubert (UCLA)
Calculations of the tidal responses of Ganymede and Callisto reveal that tidal amplitudes on these bodies may be as large as a few meters if a liquid ocean exists to decouple the surface ice from the interior. The total tidal variation (twice the amplitude) for a Ganymede model with a thick (120 km) ice shell overlying a thin (20 km) ocean is 5 to 7 meters for ice rigidity of 1010 and 109~Pa, respectively, while a similar model on Callisto (150 km thick shell overlying a 20 km thick ocean) has 3.5 to 5.5 meters of variation for the same rigidity values. Since it is the product of the shell's thickness and rigidity which largely determines the tidal amplitude, thin shells will show less variation in tidal amplitude with rigidity. The implications of these tidal amplitudes for the thermal state of the icy shells and the longevity of the underlying oceans on Ganymede and Callisto are studied using a self-consistent model of coupled tidal heating and convective (or conductive) heat transport. These models show that even Callisto's ocean may be a long-lived feature.
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.