Detecting a deep ocean within Europa by means of geodetic measurements.

The influence of the internal structure on the diurnal response of Europa to Jovian tides is established for several series of models. The presence of an ocean can be detected if altimetric measurements are performed with an accuracy better than 10 m and if degree 2 gravity coefficients are calculated with an uncertainty lower than 10(-6). An order of magnitude of better accuracy should allow for the determination of the thermally conductive shell thickness and density of the ocean, and two orders of magnitude of better accuracy are required to estimate the core radius of an oceanless model with a precision of 50 km. (C) 2000 Academie des sciences / Editions scientifiques et medicales Elsevier SAS.