Journal article
Cassini plasma spectrometer measurements of Jovian bow shock structure
Journal of geophysical research. Space physics, Vol.108(A7), pp.1287-n/a
07/2003
DOI: 10.1029/2002JA009517
Abstract
The Cassini spacecraft on its way to Saturn flew by Jupiter and crossed its bow shock more than forty times on the dusk-side of the planet, whereas the early missions targeting Jupiter explored the dawnside. Here we report the first results concerning these bow shock crossings, based on the measurements of the Cassini Plasma Spectrometer (CAPS), the magnetometer, and the radio and plasma wave science (RPWS) instrument. We present data for five bow shock crossings, one at about 1920 local time (LT), the other four between 2100 and 2130 LT, 47.5 degrees-50 degrees beyond terminator. During the flyby the solar activity was high and variable. The measurements confirm that the Jovian bow shock is huge, extending over 700 R-J down the flank; Cassini was the first to observe such distant shock features. The bow shock was turbulent and very dynamic and magnetic fluctuations were superimposed on the shock; the downstream ion distributions exhibited bimodal structure time to time. For all bow shock crossings the onset of ion thermalization was a clear shock signature supported by an electrostatic wave signal; thermalization can be used as a signature of the shock location even in those cases when the field data are rather smeared. The strength of the shock potential weakened toward more distant regions even if the local Mach number did not decrease. Reflected protons were not detected upstream above our current sensitivity limit, but the incoming solar wind fluctuated in the foot region. We argue that the Jovian bow shock is not always in a steady state, and some of the observations might be connected with this fact.
Details
- Title: Subtitle
- Cassini plasma spectrometer measurements of Jovian bow shock structure
- Creators
- Karoly Szego - Institute for Particle and Nuclear PhysicsDavid T. Young - SW Res Inst, San Antonio, TX 78228 USABruce Barraclough - Los Alamos Natl Lab, Space & Atmospher Sci Grp, Los Alamos, NM 87545 USAJean-Jacques BerthelierAndrew J. Coates - Univ Coll London, Mullard Space Sci Lab, Dorking RH5 6NT, Surrey, EnglandDavid J. McComas - SW Res Inst, San Antonio, TX 78228 USAFrank J. Crary - SW Res Inst, San Antonio, TX 78228 USAMichele K. Dougherty - University of LondonGeza Erdos - KFKI Res Inst Particle & Nucl Phys, H-1121 Budapest, HungaryDonald A. Gurnett - Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USAWilliam S. Kurth - Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USAMichelle F. Thomsen - Los Alamos Natl Lab, Space & Atmospher Sci Grp, Los Alamos, NM 87545 USA
- Resource Type
- Journal article
- Publication Details
- Journal of geophysical research. Space physics, Vol.108(A7), pp.1287-n/a
- Publisher
- Amer Geophysical Union
- DOI
- 10.1029/2002JA009517
- ISSN
- 2169-9380
- eISSN
- 2169-9402
- Number of pages
- 14
- Grant note
- PPARC; European Commission 961152 / NASA; National Aeronautics & Space Administration (NASA) T-32634 / Hungarian OTKA; Orszagos Tudomanyos Kutatasi Alapprogramok (OTKA)
- Language
- English
- Date published
- 07/2003
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984455557302771
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