Dynamics of dust ejected from Enceladus: Application to the Cassini dust detector

The satellite Enceladus is obviously the main source of Saturn's E ring. Up to now, different mechanisms of how particles are delivered from this sate llite have been suggested. In this paper, we try to answer the question of whether these different launch processes can be. distinguished by the cosmi c dust analyzer;(CDA) aboard the Cassini spacecraft. To this aim, the dynam ics of dust particles just launched from the surface of Enceladus is studie d numerically. We have integrated the equations of motion for a wide range of initial conditions including ejecta from interplanetary and E ring impac tors onto Enceladus. According to our simulations, Cassini will encounter a significant dust stream about the time of closest approach to Enceladus. T he duration and intensity of this expected enhanced impact rate onto the CD A depends on the way the particles are ejected from the satellite. The coun ting rate yields information about the distribution of ejecta sources on th e surface of Enceladus. For instance, an anisotropy of the ejecta between t he leading and the trailing hemispheres of Enceladus should be detectable, and impactors of different origin should be distinguishable. Furthermore, t he vertical component of the ejecta velocities can explain the vertical ext ent of the E ring.