A chance of rain: investigating the effects of stochastic charging on the orbital dynamics and precipitation of nanodust in Saturn’s rings

Abstract

ABSTRACT The precipitation of dusty material via unstable orbits on to Saturn from the ring plane is a phenomenon known as ring rain. A key open question for Saturn’s rings is whether silicates and organics rain out of the rings on to Saturn faster than water ice. Such preferential precipitation of dusty material would ‘clean’ the rings and make them appear youthful. In this paper, we investigate the stability of orbiting dust that is stochastically charged and may precipitate on to the planet, be ejected from the system, or remain stable over the duration of our numerical integrations. We find no clear relationship between dust particles’ launch locations in the main rings and their final deposition latitudes on the planet because the orbital motion is sensitive to initial conditions and the charging environment, but averaging over distributions of dust particle properties should lead to high-resolution stability maps for dust in the rings and deposition distributions on the planet, and hence predictions for the observable $\rm H_3^+$ emission strength.