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| Titel |
Global directional distribution of the hydrogen energetic neutral atom emission from Mars as measured by Mars Express ASPERA-3 |
| VerfasserIn |
X.-D. Wang, S. Barabash, Y. Futaana, A. Grigoriev, P. Wurz |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250067640
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| Zusammenfassung |
| We used the data obtained by the Neutral Particle Detector(NPD) of Analyzer of Space
Plasma and Energetic Atoms(ASPERA-3) on Mars Express(MEX) to derive the global
directional distribution of hydrogen energetic neutral atoms (ENAs) around Mars. The NPD
instrument package consists of two identical neutral particle energy spectrometers with
direction resolving capability. Either instrument has an energy range of 100 eV~10 keV, and
a factual angular resolution(full-width-half-maximum) of 5°Ã40° covering the total filed of
view 9°Ã180° in six pixels in the fan-geometry. The data used in this study cover 5 months,
from March 14, 2004 to August 17, 2004. The directional flux distribution of hydrogen ENAs
was first converted to the MSE (Mars centered solar electric field) frame constructed by the
direction of the Sun, the magnetic field component perpendicular to the Sun-Mars line
and the convection electric field. MGS proxies for the interplanetary filed were
used. The directional flux distributions along each orbit were then projected on
a sphere centered at Mars with a radius of 100 Mars radii in order to isolate the
direction distribution of ENA from the position variation of the spacecraft. From the
projection, we obtained a sky map of ENA flux pointing away from Mars. The sky
map shows large ENA flux in the direction of positive convection electric field
and moderate flux in a cone facing the Sun. These two populations correspond to
so-called ENA jets originated in the magnetosheath, which turned out to be strongly
asymmetric regarding to the electric field direction, and ENAs backscattered from the
upper atmosphere. We also investegated the correlations of ENA signatures to the
solar wind pressure, F10.7 irradiance and the local time of the Martian magnetic
anomalies. |
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