Planetary Science Seminar spring-2016

Saturn's rings seen by Cassini spacecraft

NASA/ESA's Cassini spacecraft entered Saturn orbit in 2004 after a travel of seven years. Now in its 12th year orbiting Saturn, Cassini has completed more than 200 orbits around the planet with the enigmatic rings. Indeed, Saturn’s rings are one of the most prominent and dramatic features of the solar system, however, their origin and age are still matter of debate. Clues to the evolution of the rings exist in the complex structure the ring particles. While called "particles", the individual ring constituents can be pretty big: ranging from micron-sized dust to tens of meters. The Composite Infrared Spectrometer (CIRS) and the Imaging Science Subsystem (ISS) on Cassini have observed the rings in various geometries and an almost full season. These measurements provide informations on the micro-structure of the rings, such as albedo, composition and thermal inertia of the ring regolith. Comparisons of CIRS and ISS data at a specific geometry called the "opposition" are also very valuable for the macro-structure of the rings. This opposition effect has revealed details about the spatial distribution of the ring particles. In addition, optical and thermal infrared data have revealed interesting behaviors in the C ring plateaus. These structures are enigmatic and remain so far unexplained by current models. I will provide an overview of the ring system and the observations of Saturn’s rings made with CIRS and ISS and discuss their implications for understanding the evolution of the ring system.