In-situ Measurements of Saturn's Dusty Rings Based on Dust Impact Signals Detected by Cassini RPWS

Abstract:

The Cassini Radio and Plasma Wave Science (RPWS) instrument can detect dust particles when voltage pulses induced by dust impacts are observed in the wideband receiver. The size of the voltage pulse is proportional to the mass of the impacting dust particle times the impact speed to the power of ~4.6. The dust density can be calculated based on counting individual dust impacts in the waveform snapshots. In this study, we show RPWS measurements of dust particles in Saturn's dusty rings. The differential size distribution of the dust particles can be characterized as a power law dn/dr ≈ r^μ where μ ~ -4 and r is the particle radius. Dust density profiles of the dusty rings are derived from the RPWS wideband receiver data, which revealed interesting structures. The vertical scale height of the dusty rings varies with the radial distance from Saturn with local minima at the G-ring and Enceladus' orbit. The vertical profiles show a dip at the equatorial plane near Enceladus' orbit and vertical offsets of the peak locations away from Enceladus' orbit. These observations are compared with the modeling studies and measurements by other instruments onboard Cassini.