Plasma and charged dust around Enceladus

Wednesday, 16 December 2015
Poster Hall (Moscone South)
Ilka Annabel Dorothée Engelhardt1, Jan-Erik Wahlund1, David J Andrews1, Anders I Eriksson1, Shengyi Ye2, William S Kurth3, Donald A Gurnett3, Michiko W Morooka4, William M Farrell5 and Michele Karen Dougherty6, (1)IRF Swedish Institute of Space Physics Uppsala, Uppsala, Sweden, (2)University of Iowa, Physics and Astronomy, Iowa City, IA, United States, (3)University of Iowa, Iowa City, IA, United States, (4)LASP, University of Colorado, Boulder, CO, United States, (5)NASA Goddard SFC, Greenbelt, MD, United States, (6)Imperial College London, Blackett Laboratory, London, SW7, United Kingdom
Using the Langmuir probe and the electric antenna connected to the wideband receiver of the radio and plasma wave science (RPWS) instrument package as well as the magnetometer (MAG) we show that there are three main plasma and dust regions around Enceladus. (1) The plume region, filled with neutral gas, plasma and charged dust, the (2) plume edge region and (3) downstream dust trail region. The dust is observed by both the difference of ion and electron densities as measured from the Langmuir probe as well as directly from the signals by dust impacts on the spacecraft as measured by the RPWS antennas, with excellent agreement for the dust distribution in space inferred by these two independent methods. The observations are consistent with a simple power law for the dust size distribution with the smallest sizes of dust particles inferred to be 1 nm in the plume region and 10 nm in both the plume edge region as well as the trail region. From the magnetic field measurements we infer strong field-aligned edge currents, southwards toward Saturn and northwards away from Saturn.