SM42B-05
Pickup Ions in the Plasma Environments of Mars, Comets, and Enceladus
Thursday, 17 December 2015: 11:20
2009 (Moscone West)
Thomas Cravens1, Ali Rahmati1, Shotaro Sakai2, Hadi Madanian1, Davin E Larson3, Robert J Lillis3, Jasper S Halekas4, Ray Goldstein5, James L Burch5, George B Clark6 and Bruce Martin Jakosky7, (1)University of Kansas, Lawrence, KS, United States, (2)University of Kansas, Physics & Astronomy, Lawrence, KS, United States, (3)Space Sciences Laboratory, Berkeley, CA, United States, (4)University of Iowa, Physics and Astronomy, Iowa City, IA, United States, (5)Southwest Research Institute, San Antonio, TX, United States, (6)Catholic University of America, Washington, DC, United States, (7)Laboratory for Atmospheric and Space Physics, Boulder, CO, United States
Abstract:
Ions created within a flowing plasma by ionization of neutrals respond to the electric and magnetic fields associated with the flow becoming what are called pick-up ions (PUI). PUI play an important role in many solar system plasma environments and affect the energy and momentum balance of the plasma flow. PUI have been observed during several recent space missions and PUI data will be compared and interpreted using models. Pick-up oxygen ions were observed in the solar wind upstream of Mars by the Solar Energetic Particle (SEP) and Solar Wind Ion Analyzer (SWIA) instruments on NASA’s MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft. The pick-up oxygen ions are created when atoms in the hot corona are ionized by solar radiation and charge exchange with solar wind protons. The ion fluxes measured by SEP can constrain the oxygen escape rate from Mars. PUI were also been detected at distances of 10 - 100 km from the nucleus of comet 67P/Churyumov- Gerasimenko (67P/CG) by plasma instruments (IES and ICA) onboard the Rosetta Orbiter when the comet was at 3 AU. The newly-born cometary ions are accelerated by the solar wind motional electric field but remain un-magnetized, as suggested by pre-encounter models (Rubin et al., 2014). The inner magnetosphere of Saturn and the water plume of the icy satellite Enceladus provide a third example of PUI. H2O+ ions created by ionization of neutral water producing ions that are picked-up by the co-rotating magnetospheric plasma flow. These ions then undergo a complex interaction with the plume gas including collisions that convert most H2O+ ions to H3O+, as measured by the Ion and Neutral Mass Spectrometer (INMS) onboard the Cassini spacecraft.
