Structure and Evolution of Jupiter's Ring System

Grant #: NNX09AD97G
Senior Scientist: Mark Showalter

Our key data sets on the Jovian ring system---from Voyager, Galileo, Cassini, HST and now New Horizons, span a time baseline of 28 years. Using this combined information, this study investigates the spatial and temporal variations within the rings to understand the dynamics, evolution and origin of the system. (a) A study of the longitudinal asymmetries in the ring, which were seen clearly by Voyager and Galileo but not by Cassini or New Horizons. We will quantify the level of the changes observed and try to understand the cause. (b) A study of the evidence for vertical "ripples" in the main ring, seen in a few of the finest Galileo images but not before or since. We will determine whether their non-detection by New Horizons is due to instrumental limitations or genuine changes in the ring, and will explore a variety of possible explanations. (c) A study of the radial structure and thickness of the main ring to understand the influence of the ring-moons Metis and Adrastea, the dynamics of the parent bodies, and the relationship between the parents and the prevalent dust. (d) Astrometry and orbit modeling of the two moons to clarify their connection to the ring; also, any sign of interactions between them would have implications for the long-term stability of the ring. (e) A study of the 3-D structure of the inner "halo" and outer "gossamer rings" to understand the effects of both gravitational and non-gravitational forces on their orbital motion. This work supports NASA's strategic goal to "advance scientific knowledge of the origin and history of the solar system..." and the JDAP program's goal to "to enhance the scientific return of the Jupiter science data obtained by the New Horizons spacecraft, as well as the Voyager, Galileo, and Cassini spacecraft."