P31E-2101
The Evolution of Comet 67P as Seen by a Mass-Resolving Ion Spectrometer
Wednesday, 16 December 2015
Poster Hall (Moscone South)
Gabriella Stenberg Wieser1, Hans Nilsson1, Etienne Behar1, Cyril Simon Wedlund2, Esa Jukka Kallio2, Herbert Gunell3, Niklas J. T. Edberg4, Anders I Eriksson4, Masatoshi Yamauchi1, Christoph Koenders5, Martin Wieser1, Rickard N A Lundin1, Kathleen Mandt6, James L Burch6, Ray Goldstein6, Pat Mokashi6, Chris Carr7, Emanuele Cupido8, Peter T Fox8, Karoly Szego9, Zoltan Nemeth9, Andrei Fedorov10, Stas Barabash1, Jean-André Savaud10, Hannu E J Koskinen11, Ingo Richter12, Jean-Pierre Lebreton13, Henri Pierre14, Martin Volwerk15, Claire Vallat16 and Bernhard Geiger17, (1)IRF Swedish Institute of Space Physics Kiruna, Kiruna, Sweden, (2)Aalto University School of Engineering, Espoo, Finland, (3)Belgisch Instituut voor Ruimte-Aeronomie, Brussel, Belgium, (4)IRF Swedish Institute of Space Physics Uppsala, Uppsala, Sweden, (5)Institute for Geophysics and extraterrestrial physics, Braunschweig, Germany, (6)Southwest Research Institute, San Antonio, TX, United States, (7)Imperial College, London, United Kingdom, London, United Kingdom, (8)Imperial College London, London, United Kingdom, (9)Hungarian Academy of Sciences, Budapest, Hungary, (10)IRAP, Toulouse, France, (11)University of Helsinki, Helsinki, Finland, (12)Technical University of Braunschweig, Braunschweig, Germany, (13)University of Orleans, Orleans, France, (14)CNRS, Paris Cedex 16, France, (15)Austrian Academy of Sciences, Vienna, Austria, (16)ESAC, Villanueva, Spain, (17)European Space Agency, Villanueva de la Canada, Spain
Abstract:
We study comet 67P/Churyumov-Gerasimenko using the mass-resolving ion spectrometer RPC-ICA (Rosetta Plasma Consortium-Ion Composition Analyzer) onboard the Rosetta spacecraft. RPC-ICA measures both solar wind ions and ions of cometary origin in the energy range 10 eV–40 keV with high angular resolution.
We observe the evolution of the ion environment close to the comet as the distance to the sun changes. At a distance of 3.6 AU the instrument detects the first water ions from the comet but the comet activity is still low and the solar wind passes through the thin atmosphere without being much affected. The situation gradually changes as the comet moves closer to the sun and the cometary atmosphere develops. Mass loading becomes important, the solar wind is deflected and large fluxes of accelerated cometary ions are observed. We characterize the changes of the ion environment in terms of ion fluxes and energy spectra as the comet moves from 3.6 AU through perihelion. We look at both long-term and short-term variations and investigate which timescales are important.
