Influence of Low Europa Orbit design on gravity field recovery

Abstract

The characterization of Europa's surface and interior ocean and ice shell is key to explore the habitability of the fourth largest moon of Jupiter. Europa Clipper will largely contribute to our knowledge of Europa with multiple dedicated flybys. However, global mapping can only be significantly improved by means of an orbiter with high inclination and low altitude, as it will be done in the case of Ganymede by JUICE. This was the strategy of several mission proposals (Joint Europa Mission, Jupiter Europa Orbiter, HADES). A specific difficulty in designing suitable orbits in the Jovian system is related to the orbit stability, which is highly impacted by the influence of Jupiter as a third body exerting strong perturbations on a Europa orbiter. This results in constraints for potential science orbits which would allow, e.g., for the determination of Europa's gravity field using radio tracking to the probe. In this presentation, we will analyze a set of different low Europa orbits and compare their scientific value for gravity field recovery. We will explore different orbital characteristics, with the possibility to use repetitive ground track orbits. The analysis will be performed based on closed-loop simulations using the planetary extension of the Bernese GNSS Software. We simulate realistic Doppler tracking data (2-way X-band Doppler range rate) from the Deep Space Network. These observations are then used to reconstruct the orbit as well as geodetic parameters, such as Europa gravity field parameters and the tidal Love number k2. We will discuss the quality of the retrieved solutions.