P11D-02
Enceladus Flyby 21: The Final Cassini INMS Flyby
Monday, 14 December 2015: 08:16
2009 (Moscone West)
Jack H Waite Jr1, Benjamin D Teolis2, Mark E Perry3, Alexis Bouquet4, Christopher Glein1, Rebecca Perryman1 and The Cassini INMS Team, (1)Southwest Research Institute San Antonio, Space Sciences and Engineering, San Antonio, TX, United States, (2)Southwest Research Institute, San Antonio, TX, United States, (3)Applied Physics Laboratory Johns Hopkins, Laurel, MD, United States, (4)University of Texas San Antonio, Physics and Astronomy, San Antonio, TX, United States
Abstract:
The last Cassini Ion and Neutral Mass Spectrometer dedicated fly through of the Enceladus’ southern plume 50 km above the surface (at 8.5 km s-1) occurred on October 28, 2015. A new operational mode was designed to specifically look at the outflowing gas composition as a function of position along the tiger stripes. This open ion source beaming mode was used in the design to unambiguously determine the composition of the plume gases without the concern of instrument wall effects that have previously been shown to occur in the closed ion source during high velocity flybys (>16 km s-1). Of particular interest was the H2 content of the plume gas due to its importance for verifying the existence of hydrothermal processes in the internal sea. The existence and quantity of H2 taken together with the plume abundance of methane and the Cosmic Dust Analyzer measurement of silicon dioxide nanoparticles will provide conclusive evidence of the existence of extant hydrothermal activity thus setting the stage for future missions to verify the habitability and conditions of the internal sea and to search for life therein.
