Characterising the interior of five inner Saturnian moons using <i>Cassini</i> ISS data

Context. The Cassini-Huygens space mission provided a huge amount of data for the Saturnian system. While ended in September 2017, there is still much information to be retrieved from data. Aims. Here, their orbital motion, we infer interior five inner moons, Atlas, Prometheus, Pandora, Janus, and Epimetheus. Our results benefit recent study shape these which provides better estimation 3D volume. Methods. Using Cassini Imaging Science Subsystem (ISS) astrometric data, again reduced ISS images with an improved modelling. We then integrated motion moons solved large set physical parameters this system, including masses libration amplitudes moons. Results. obtain density value (in g cm −3 1 σ error bar based on digital terrain models spherical harmonics available today) 0.3935 ± 0.0033, 0.4873 0.0026, 0.5045 0.0017, 0.6233 0.0015, 0.6413 0.0002 Epimetheus, respectively. were able determine Janus 0.98 0.08, −5.2 0.7, −6.0 0.6, −0.39 0.16 (degrees bar), solutions Epimetheus are full agreement former performed directly measurement rotation two Conclusions. confirm porosity increase as function size. estimations librations consistent homogeneous interior, but Pandora heterogeneous also plausible.