Physics of Cosmic Dust
Saturn's diffuse E ring composed of ice grains (radius ~1µm) is the biggest planetary ring in the solar system. This ring is an analogue for debris discs around young stars as ß-pictoris. Based on optical measurements the ring was surprisingly found to mainly consist of ice particles of uniform size (radii between 0.3 and 2 µm), though the source of the ring, the icy moon Enceladus, feeds the ring with grains having a much broader mass distribution. Because of this contra-diction, the mass distribution of the ring must be closely connected to the dynamics of the ring particles which is governed by the com-petition of various disturbing forces acting on the grains. Recent CDA measurements are even more difficult to square with theoretical ring models. In particular, the narrow size distribution of the ring particles is still a mystery. Currently I‘m working on methods to extract the distribution of the ring particle‘s orbital elements from CDA measurements, on models for the ring‘s source, and on the ring particle charging.
One of the most enigmatic discoveries of the Galileo, Ulysses, and Cassini missions are the existence of collimated quasi-periodic streams of nano-sized dust grains emerging from both the inner Jovian and Saturnian system.