Enceladus Plume Density from Cassini Spacecraft Attitude Control Data.

ABSTRACT: The plumes of Enceladus are of interest both as a geophysical phemonenon, and as an astrobiological opportunity for sampling internal material. Here we report measurements of the total mass density (gas plus dust, a combination not reported before except in the engineering literature) deduced from telemetry of Cassini's Attitude and Articulation Control System (AACS), as the spacecraft's thrusters or reaction wheels worked to maintain the desired attitude in the presence of gas drag torques during close flybys. The drag torque shows good agreement with the water vapor density measured by other instruments during the E5 encounter, but indicates a rather higher mass density on other passes (E3,E14), possibly indicating variations in gas composition and/or gas:dust ratio. The spacecraft appea

SUBMITTER: Lorenz RD 

PROVIDER: S-EPMC6278931 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature