Can Cassini detect a subsurface ocean in Titan from gravity measurements?
Iess, Luciano; Tortora, Paolo; Lunine, Jonathan I.; Rappaport, Nicole J.; Wahr, John; Armstrong, J. W.; Asmar, Sami W.; Di Benedetto, Mauro; Racioppa, Paolo
United States, Italy
Abstract
Recent models of Titan's interior predict that the satellite contains an ocean of water and ammonia under an icy layer. Direct evidence for the presence of an ocean can be provided on the Cassini mission only by radio science determination of Titan Love number k. Simulations that use the five flybys T11, T22 T33, T45, and T68 (the latter two belonging to the extended mission) lead to the result that in the elastic case, where the Love number is real, k will be determined with a one-sigma accuracy of 0.1. In the viscoelastic case, where k is complex, the real and imaginary parts of k will be determined with one sigma accuracies of 0.138 and 0.115, respectively. Ocean and oceanless models that include a viscoelastic rheology are built. In the viscoelastic case, there is a 93% probability to correctly predict the presence or absence of an ocean; this probability improves to 97% in the elastic case.