Is it possible to detect large ocean floor structures in the gravity field of Europa?

Kurzfassung

The data provided by the Galileo mission suggested the existence of a deep water ocean at the Jupiter's moon Europa. This fact motivates the future plans for the Outer Solar System exploration because the presence of water and inner energy of this satellite - which is likely a consequence of the tidal heating from Jupiter - gives a chance for primitive life-forms to evolve. A part of the internal energy is released through the tectonic activity observed on the ice shell which surrounds that subsurface ocean. However, another part of the inner energy could drive the tectonics also on the oceanic floor, i.e. on the water/silicate boundary. If we find a way how to look underneath the top ice/water layer we could learn about the structures present on this boundary, e.g. volcanoes, rifts, etc. One of the possible ways to do that is the inversion of the gravity field, which reflects the mass distribution within the moon. Our study focus on a possibility to detect such large ocean floor features in the gravity data from some future Europa obiter mission. We test various tectonic structures (different in size and compensation state) based on the real planetary topography analogs to obtain the minimum size of those features which could be recovered from the gravity field inversion. We also study the needed resolution of the gravity data and the accuracy of the anticipated measurements. Finally, we test the inversion procedure on the global synthetic topography with embedded tectonic features to check the results in the presence of the observation noise.