Plume dust mass density derived from dust impact plasma measured by in situ Cassini instruments at Enceladus

The plume of Enceladus is one of the most complex space plasma environments ever explored. Every second, hundreds of kilograms of water vapor and ice grains are emitted from subsurface liquid water reservoirs, interacting with Saturn’s magnetosphere. Abundant ice grains micron-sized and smaller were suggested to be a significant plasma electron sink in the dusty plume. However, recent reanalysis of Cassini in situ plume measurements suggests that dust impact plasma, i.e., low-temperature plasma produced from high-speed dust impacts, has significant effects on both Cassini Plasma Spectrometer (CAPS) and Langmuir probe (Radio and Plasma Wave Sciences) data. Taking impact plasma production into account, our analysis utilizes multiple in situ dataset over various plume crossings and provides direct constraints on the plume dust mass density agnostic to grain size distribution. 

This presentation will focus on comparing the Cassini Langmuir probe and CAPS dataset from multiple Enceladus flybys to quantify the impact plasma effects. We will also compare the derived plume dust mass density from these two independent measurements.