HR: 1340h
AN: P33B-1301    [Abstracts]
TI: Plasma Wave Activity Near Venus as Seen by the Venus Express Spacecraft
AU: * Guicking, L
EM: l.guicking@tu-bs.de
AF: Institute for Geophysics and extraterrestrial Physics, Mendelssohnstr. 3, Braunschweig, 38106, Germany
AU: Glassmeier, K
EM: kh.glassmeier@tu-bs.de
AF: Institute for Geophysics and extraterrestrial Physics, Mendelssohnstr. 3, Braunschweig, 38106, Germany
AU: Auster, H
EM: uli.auster@tu-bs.de
AF: Institute for Geophysics and extraterrestrial Physics, Mendelssohnstr. 3, Braunschweig, 38106, Germany
AU: Zhang, T
EM: Tielong.Zhang@oeaw.ac.at
AF: Austrian Academy of Sciences Space Research Institute, Schmiedlstr. 6, Graz, 8042, Austria
AU: Delva, M
EM: magda.delva@oeaw.ac.at
AF: Austrian Academy of Sciences Space Research Institute, Schmiedlstr. 6, Graz, 8042, Austria
AU: Fraenz, M
EM: fraenz@mps.mpg.de
AF: Max Planck Institute for Solar System Research, Max-Planck-Str. 2, Katlenburg-Lindau, 37191, Germany
AU: Martinecz, C
EM: martinecz@mps.mpg.de
AF: Max Planck Institute for Solar System Research, Max-Planck-Str. 2, Katlenburg-Lindau, 37191, Germany
AB: We present a wave activity map of the Venusian space environment obtained from data of the Venus Express (VEX) magnetometer (MAG). Venus Express is the first European mission to the planet Venus and was inserted in a polar orbit with a duration of 24 hours in April 2006. Due to its different orbit in comparison to the long lasting mission of the Pioneer Venus Orbiter (PVO), it can complete the lack of measurments and leads to a better understanding of the processes occurring within the Venusian magnetosphere and the interaction between the solar wind and the planet's atmosphere. The magnetometer onboard VEX measures the magnetic field vector continously during one orbit. We used for our calculations the data from April to December 2006 with a resolution of four seconds. We made a Fourier Analysis of this data set and determined a mean value of the power spectral densities in different frequency bands. In doing so, we were mainly interested in ultra low frequency (ULF) waves, whose frequencies are less than the gyro-frequencies of the typical species in that region. The wave activity maps show a region of enhanced activity in the magnetosheath between the subsolar point and the terminator. Ion density measurements of the ASPERA-4 instrument onboard VEX shall help to explain these results by determination of the Alfvén velocity, in particular the Alfvén Mach number. We speculate that regions of high wave activity and regions of sub-Alfvén Mach numbers are in general overlapping, because the waves there can propagate in all directions. We discuss this phenomenon, including possible reasons for the occurrence.
DE: 2780 Solar wind interactions with unmagnetized bodies
DE: 6295 Venus
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting