In-mission synergy of science and navigation ephemeris products—Potential benefits for JUICE statistical Delta-V expenditure and beyond

Abstract

In 2031 the JUICE spacecraft will perform a multi-flyby tour of the Jovian system. Next to the radiometric tracking that is performed for navigation operations, the dedicated radio science instrument (3GM) collects high-accuracy radiometric measurements during the flybys.

We investigate the capability of the radio science data to provide improved moon state knowledge during navigational operations. We introduce ephemeris updates from radio science data into our simulated navigation operations and examine the potential savings of statistical $\Delta V$ for corrective manoeuvres. A navigation orbit determination (OD) solution was simulated for the multi-flyby tour of JUICE, including the resulting state knowledge evolution of the Galilean moons. The OD was extended by an interface for external moon ephemeris updates, which was used to evaluate the impact of radio science generated external ephemerides on the statistical $\Delta V$ budgets for post-flyby cleanup manoeuvres.

The moon state knowledge evolution during navigation operation showed a rapid reduction of the a-priori moon state uncertainty, for which the navigational tracking data coverage of the long, early tour arcs was identified as the driving factor. As a result of the longer tracking arcs, the moon state knowledge from navigation data results improves more quickly during the initial phase of the tour. Since the impact of moon state knowledge on the corrective manoeuvres is largest in this initial phase, the comparative analysis of the statistical $\Delta V$ cost shows that the adoption of radio science ephemeris products does not effectuate significant $\Delta V$ savings. Instead we showed that in order to achieve substantial $\Delta V$ savings improvements of Europa’s and Ganymede’s ephemerides are required ahead of JUICE’s arrival.

While the analysis concludes that data synergies are unlikely to benefit the navigational operations, it highlights other potential synergies between the navigation and radio science data. A comparatively strong signature of Io’s dynamics was found in the simulated navigation data along the long early tour arcs, which could be leveraged for the benefit of the new global moon ephemeris solutions after JUICE.