The detection of Jupiter normal modes with gravity measurements of the mission Juno

Arriving at Jupiter on July 4, 2016, NASA’s Juno mission will complete 37 orbits (14-days period) around the planet, revealing details of the interior structure and composition, a crucial aspect to understand the origin and evolution of Jupiter. A radio science experiment will help to select and validate the existing models of Jupiter internal composition, in particular the mass of the silicate core. Recently it has been proposed to exploit the Doppler data for the determination of Jupiter’s acoustic normal modes. Jupiter is a gaseous giant and its masses are subject to oscillations (normal modes) due to internal pressure waves, which cause potentially detectable disturbances in the gravity field. By displacing large masses, Jupiter’s normal modes can therefore perturb the spacecraft motion to levels that can be measured by Juno’s extremely accurate Doppler system. Theoretical models that explain these phenomena have been proposed in the past and experimental works looking for these oscillations have been carried out recently with ground-based optical telescopes. But the frequencies and the amplitudes of normal modes can in principle be modeled and estimated by means of orbit determination codes.