On the contribution of PRIDE-JUICE to Jovian system ephemerides

Abstract

The Jupiter Icy Moons Explorer (JUICE) mission will perform detailed measurements of the properties of the Galilean moons, with a nominal in-system science-mission duration of about 3.5 years. Using both the radio tracking data, and (Earth- and JUICE-based) optical astrometry, the dynamics of the Galilean moons will be measured to unprecedented accuracy. This will provide crucial input to the determination of the ephemerides and physical properties of the system, most notably the dissipation in Io and Jupiter.The data from Planetary Radio Interferometry and Doppler Experiment (PRIDE) will provide the lateral position of the spacecraft in the International Celestial Reference Frame (ICRF). In this article, we analyze the relative quantitative influence of the JUICE-PRIDE observables to the determination of the ephemerides of the Jovian system and the associated physical parameters. We perform a covariance analysis for a broad range of mission and system characteristics. We analyze the influence of VLBI data quality, observation planning, as well as the influence of JUICE orbit determination quality. This provides key input for the further development of the PRIDE observational planning and ground segment development.Our analysis indicates that the VLBI data are especially important for constraining the dynamics of Ganymede and Callisto perpendicular to their orbital planes. Also, the use of the VLBI data makes the uncertainty in the ephemerides less dependent on the error in the orbit determination of the JUICE spacecraft itself. Furthermore, we find that optical astrometry data of especially Io using the JANUS instrument will be crucial for stabilizing the solution of the normal equations. Knowledge of the dissipation in the Jupiter system cannot be improved using satellite dynamics obtained from JUICE data alone, the uncertainty in Io's dissipation obtained from our simulations is similar to the present level of uncertainty

Analytical ray-tracing in planetary atmospheres

“…V, could be developed in order to process real AO data in the context of past, current, and future space missions. Our next opportunity, which actually motivated this work, is ESA's L-class mission JUICE (JUpiter Icy moons Explorer) [44,45]; here a radioscience experiment named 3GM (Gravity and Geophysics of Jupiter and the Galilean Moons) will take advantage of a careful Jupiter system tour design [46], offering both frequent Jupiter moon's flybys [47,48] and radio occultation opportunities by Jupiter's oblate atmosphere.…”

Measuring Ganymede’s Librations with Laser Altimetry

“…Pointing errors reflecting the uncertainties in the transmitter alignment and in the orientation of the spacecraft with respect to nadir are randomized assuming a Gaussian distribution with random azimuth. The assumed amplitudes are 5 m along-track, 2 m cross-track, and 0.5 m radial [37], and the pointing knowledge error is assumed to be 20 arcseconds (all values 1-sigma). The synthetic measurements are in the ICRF with respect to Ganymede's center of mass and are therefore independent of the assumed rotational state or global topography.…”

Venus Express radio occultation observed by PRIDE

“…This is achieved by performing precise Doppler tracking of the spacecraft carrier signal and near-field VLBI observations in phase-referencing mode (Duev et al 2012(Duev et al , 2016Bocanegra-Bahamón et al 2018). PRIDE is suitable for various applications in planetary and space science, such as determination of planetary ephemerides (Dirkx et al 2017), characterization of the interplanetary plasma (Molera et al 2014) and detection of interplanetary coronal mass ejection (ICME) (Molera et al 2017). In this work we present another application: the characterization of planetary atmospheres and/or ionospheres by means of radio occultation observations.…”