Image of Saturn and its rings taken by the Cassini spacecraft. Courtesy NASA/JPL-Caltech.
Saturn′s prominent rings − already visible with small amateur telescopes − consist of almost pure water-ice particles in the size range between 1 cm and 10 m. Owing to the Keplerian rotation of the rings, i.e. the inner regions of the ring rotate faster than the outer regions, the ring particles undergo many collisions per rotation about Saturn. These collisions happen at extremely low velocities, which are in a laboratory experiment only achievable under microgravity conditions.
In a first approach, we intend to study single-particle collisions to derive the energy loss per collision and the importance of ice-grain rotation. These properties are crucial ingredients for dynamical models of Saturn′s rings, with which the ring thickness and the occurrence of observed collective-dynamics phenomena, like spiral waves, can be predicted. With the empirical data on the collision behaviour of ice particles, gathered in the parabolic-flight experiments, the Potsdam theory group will model many-particle effects in Saturn′s rings, with which we intend to get a deeper insight into the fascinating physics happening in a unique cosmic laboratory.