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| Titel |
Cross-terminator flow in the ionosphere of Mars |
| VerfasserIn |
Markus Fränz, Eduard Dubinin, Erling Nielsen, Anne Angsmann, Joachim Woch, Stas Barabash, Rickard Lundin, Andrei Fedorov |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250035498
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| Zusammenfassung |
| The upper ionospheres of Mars and Venus are permeated by the magnetic fields induced by
the solar wind. It is a long-standing question wether these fields can put the dense
ionospheric plasma into motion. If so, the cross-terminator flow of the upper ionosphere
could explain a significant part of the ion escape from the planets atmospheres.
But it has been technically very challenging to measure the ion flow at energies
below 20eV. The only such measurements have been made by the ORPA instrument
of the Pioneer Venus Orbiter reporting speeds of 1-5km/s for O+ ions at Venus
above 300km altitude at the terminator (Knudsen et al, GRL 1982). Since these
observations could never be confirmed by other instruments they have been debated. We
here report on new measurements of the cross-terminator ion flow at Mars by the
ASPERA 3 experiment onboard Mars Express with support from the MARSIS
radar experiment which confirm O+ flow speeds of around 6km/s with fluxes of
1.2 -
109/cm2s. We also discuss the complicated influence of the spacecraft potential on low
energy measurements. We discuss the implication of these new observation for
ion escape and possible extensions of the analysis to dayside observations which
might allow us to infer the flow structure imposed by the induced magnetic field. |
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