Analysis of the atmospheric and cryovolcanic properties of Enceladus by radio occultation experiments of Cassini

The proposed work, developed at Boston University, analyzes radio occultation data transmitted by Cassini during two observation of Enceladus, performed in 2006 and in 2010. The aim is to determine electron densities around the satellite and within its water plumes occurring near the South Pole. The implemented methodology involves the combination of frequency data in two bands to reconstruct profiles of total electron content crossed by electromagnetic rays during their propagation. These profiles were then used to calculate local electron density profiles around Enceladus as a function of altitude, using spherical and cylindrical version of the Abel transform. Data for the two occultation revealed to be significantly affected by noise. Correction strategies were tested to improve results, with no meaningful improvements. Investigation of the ionosphere of Saturn revealed that the crossing of this region during experiments did not constitute a relevant source of disturbance. Existing in-situ electron density measurements were used to simulate the theoretically observed effects of these features in radio occultation experiments, which resulted to be smaller than uncertainties. Finally, models for water jet densities were employed to assess an upper value on plume densities observable in the experiment.