The Rosetta Ion and Electron Sensor (IES) Measurement of the Development of Pickup Ions from Comet 67P/Churyumov-Gerasimenko

Thursday, 18 December 2014
Raymond Goldstein1, James L Burch2, Pat Mokashi1, Craig J Pollock3, Tom Broiles1, Kathleen Mandt2, Thomas Cravens4, Marilia Samara3, Anders I Eriksson5, Chris Carr6, Jean-Pierre Lebreton7, Pierre Henri8, Karl-Heinz Glassmeier9, Hans Nilsson10 and Christoph Koenders9, (1)Southwest Research Institute, San Antonio, TX, United States, (2)Southwest Research Institute San Antonio, San Antonio, TX, United States, (3)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (4)University of Kansas, Lawrence, KS, United States, (5)IRF Swedish Institute of Space Physics Uppsala, Uppsala, Sweden, (6)Imperial College, London, United Kingdom, London, United Kingdom, (7)University of Orleans, Orleans, France, (8)Laboratoire de Physique et Chimie de l'Environnement et de l'Espace, Orléans Cedex 2, France, (9)Technical University of Braunschweig, Braunschweig, Germany, (10)IRF Swedish Institute of Space Physics Kiruna, Kiruna, Sweden
The Ion and Electron Sensor (IES) on Rosetta measures 3D fluxes of electrons and total ions over an energy/charge range from 4 eV to 20 keV. The field of view is swept electrostatically over 2.8 pi steradians with energy resolution of 4% and angular resolution of 5 x 22.5 deg. for electrons and 5 x 45 deg. for ions except over the 45-deg. sector that typically views the solar wind, within which the resolution is 5 x 5 deg. IES is part of the 5 instrument Rosetta Plasma Consortium (RPC). IES has been measuring solar wind ions intermittently (because of S/C pointing issues) since exiting from hibernation in May 2014. On August 5, when Rosetta was ~160 km from comet 67P, IES began to see ions at its upper energy range, ~20 keV. We identify these energetic ions as ions created from neutral species emitted by the comet nucleus, photoionized by solar UV radiation and then "picked up" by the interplanetary magnetic field (IMF). These picked up ions were seen intermittently until abstract submission time on August 7, while also measuring solar wind protons at ~600 eV. The solar wind, as expected, was from the direction of the sun, whereas the energetic ions were away from the solar direction. This is also expected for pickup ions. IES continued to follow changes in the solar wind and the development of the pickup ion structure, which will be reported in this paper.