A Survey of Low-Frequency Plasma Waves in the Magnetosphere of Saturn

Abstract: The Cassini mission to Saturn carries a wide variety of instruments to investigate Saturn and its surroundings. Since Cassini is an orbiter, the spatial coverage of this mission far exceeds the few flybys made by earlier spacecraft. We focus on just one of the instruments, and conduct a preliminary analysis of data from five-channel waveform receiver (WFR) which is a part of the Radio and Plasma Wave Science instrument (RPWS). Two electric and three magnetic field components are measured in the 3 Hz to 2.5 kHz band and recorded in the time domain. Interference from other systems of the spacecraft severely complicates interpretation of the electric field spectrum below about 1 kHz. To mitigate this problem we have applied a Blackman-Harris window with a strong sidelobe attenuation, but parts of our analysis is restricted to frequencies above 1 kHz. Various algorithms have been applied to detect and discard erroneous measurements. By analyzing the data we have produced maps of spatial variations in the measured power. The region inside about 9 Saturn radii was found to be particularly active, especially in the electric field measurements. Phenomena that have been seen in the data include dust impacts, electromagnetic whistler-mode hiss and chorus, and electrostatic electron-cyclotron harmonic (ECH) emissions.