HR: 1340h
AN: SH43A-1147    [Abstracts]
TI: Atmospheric Carbon Dioxide Photoelectron Energy Peaks: An Indicator of the Morphology of Solar Wind Influence on the Martian Environment
AU: * Frahm, R A
EM: rfrahm@swri.edu
AF: Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238 United States
AU: Winningham, J D
EM: dwinningham@swri.edu
AF: Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238 United States
AU: Sharber, J R
EM: jsharber@swri.edu
AF: Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238 United States
AU: Liemohn, M W
EM: liemohn@umich.edu
AF: Space Physics Research Laboratory, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48105 United States
AU: Ma, Y
EM: yingjuan@umich.edu
AF: Space Physics Research Laboratory, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48105 United States
AU: Coates, A J
EM: ajc@mssl.ucl.ac.uk
AF: Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surry, RH5 6NT United Kingdom
AU: Linder, D R
EM: drl@mssl.ucl.ac.uk
AF: Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surry, RH5 6NT United Kingdom
AU: Soobiah, Y
EM: yijs@mssl.ucl.ac.uk
AF: Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surry, RH5 6NT United Kingdom
AU: Team, A
EM: stas@irf.se
AF: Swedish Institute of Space Physics, Box 812, Kiruna, S-981 Sweden
AB: The solar photon spectrum contains both discrete spectral lines and continuua. These emissions interact with the atmosphere of Mars to generate photoelectrons. One of the discrete lines generated by the Sun is the HeII emission at 304 Å, which ionizes carbon dioxide to form two distinct electron peaks. Direct ionization produces an electron energy peak of about 27 eV while direct ionization coupled with molecular vibration and rotation produces the second electron energy peak in the range of 21-24 eV. At Mars, the photoelectrons energy peaks are mainly generated near the exobase. Once photoionization occurs, the photoelectrons are confined to move along the local remanent magnetic field. Sometimes the direction of electron motion causes them to precipitate into the atmosphere; however, it is also probable that the photoelectrons are transported away from the planet. Interactions of these electrons in the altitude range from just above the exobase to the Mars Express apoapsis (~ 3R_m) are infrequent. Thus, the carbon dioxide generated photoelectron energy peaks may be used as a tracer, providing important information on the morphology of the atmospheric generated photoelectron population. Example data from the ELectron Spectrometer (ELS) of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) experiment on the Mars Express (MEX) spacecraft show the robustness of these spectral tracers and emphasize the role played by both the solar wind and the crustal magnetic field in determining the morphology of the photoelectron population in the Mars environment.
DE: 5435 Ionospheres (2459)
DE: 5443 Magnetospheres (2756)
DE: 6005 Atmospheres (1060)
DE: 6025 Interactions with solar wind plasma and fields
DE: 6225 Mars
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005