Probing Europa's hidden ocean from tidal effects on orbital dynamics

Recent observations of Europa suggest that the Jovian satellite may have a liquid ocean underneath its icy surface. Geophysical models indicate that t he tidal Love number k(2) has a strong dependence on the presence or absenc e of an ocean. The k(2) dependence on the ice shell thickness is also signi ficant. Measurements of the static and tidal gravity fields through their d ynamic effects on the trajectory of a low Europan orbiter can be essential in the detection of an ocean and inference of other internal structures. Co variance analyses have been carried out to assess accuracies using simulate d Doppler tracking data. With 15 days of tracking from 2 Earth stations, th e uncertainties for k(2), mantle libration amplitude and the epoch radial p osition of the spacecraft are expected to be 0.0004, 2.8 arcsec and 5.7 m, respectively. These tight constraints will strongly contribute to ocean det ection and ice thickness determination when combined with altimeter measure ments.