Dust Observations by the Radio and Plasma Wave Science Instrument During Cassini's Grand Finale

Abstract

Dust particles in the Saturn system can be detected by the Radio and Plasma Wave Science (RPWS) instrument on board Cassini via antenna voltage signals induced by dust impacts. These impact signals have been simulated in the laboratory by accelerating dust particles onto a Cassini model with electric field antennas. RPWS dust measurements have been shown to be consistent with the Cosmic Dust Analyzer. During the Grand Finale orbits, Cassini flew through the gap between the D ring and Saturn's atmosphere 22 times. In situ measurements by RPWS helped quantify the hazards posed to the spacecraft and instruments on board, which showed a micron-sized dust density orders of magnitude lower than that observed during the Ring Grazing orbits. Close inspection of the waveforms indicated a possible dependence of the impact signal decay time on ambient plasma density.