Planetary Science by Space Missions
Composition of Saturn’s Rings and Mineral Dust at Saturn
The dynamical and compositional characterization of Saturn's ring system is a prime goal of our dust detector, CDA, on-board the Cassini space craft. The outermost large and diffuse E ring is very easy to access because Cassini fly's through it on most of its orbits about Saturn. Our in situ analysis provides insights into dynamics and composition not achievable by other methods (like cameras). However, Saturn's main rings can also be investigated: In the years 2016 and 2017 Cassini will frequently dive through the small gap between the inner edge of the ring system and Saturn's upper atmosphere, allowing for compositional in situ measurements of debris particles emitted from the main rings.
In collaboration with ESA we started a project to explore exogenic mineral dust that CDA detects and that does not stem from Saturn’s ring system. The goal is to perform the complete mapping of the composition of these non-icy micro-meteoroids within the Saturnian system, and to relate the compositional information to the grains dynamics, such as to constrain the properties of their parent bodies. It is likely that we will find several dynamical and compositional independent populations with more than one origin. It might be that some particles have parent bodies inside the Saturnian system while others are captured from the outside (e.g. collisional debris from the Kuiper belt or active Trans Neptunian Objects and Centaurs) or are dust grains just crossing the Saturn’s hill sphere without being captured (like the interstellar dust component). In any case the dust grains are indirect probes of these sources and any identification of a source can be combined with a compositional analysis by the TOF mass spectra.