Kronos: exploring the depths of Saturn with probes and remote sensing through an international mission

Abstract

Kronos is a mission aimed to measure in situ the chemical and isotopic compositions of the Saturnian atmosphere with two probes and also by remote sensing, in order to understand the origin, formation, and evolution of giant planets in general, including extrasolar planets. The abundances of noble gases, hydrogen, carbon, nitrogen, oxygen, sulfur and their compounds, as well as of the D/H, 4He/3He, 22Ne/21Ne/20Ne, 36Ar/38Ar, 13C/12C, 15N/14N, 18O/(17O)/16O, 136Xe/134Xe/132Xe/130Xe/129Xe isotopic ratios will be measured by mass spectrometry on two probes entering the atmosphere of Saturn at two different locations near mid-latitudes, down to a pressure of 10 Bar. The global composition of Saturn will be investigated through these measurements, together with microwave radiometry determination of H2O and NH3 and their 3D variations. The dynamics of Saturn’s atmosphere will be investigated from: (1) measurements of pressure, temperature, vertical distribution of clouds and wind speed along the probes’ descent trajectories, and (2) determination of deep winds, differential rotation and convection with combined probe, gravity and radiometric measurements. Besides these primary goals, Kronos will also measure the intensities and characteristics of Saturn’s magnetic field inside the D ring as well as Saturn’s gravitational field, in order to constrain the abundance of heavy elements in Saturn’s interior and in its central core. Depending on the preferred architecture (flyby versus orbiter), Kronos will be in a position to measure the properties of Saturn’s innermost magnetosphere and to investigate the ring structure in order to understand how these tiny structures could have formed and survived up to the present times.