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| Titel |
Understanding the Variability of Europa's Interaction with the Jovian Magnetosphere |
| VerfasserIn |
Krishan Khurana, Xianzhe Jia, Chris Paranicas, Timothy Cassidy, Kenneth Hansen |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250088922
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| Publikation (Nr.) |
 EGU/EGU2014-3106.pdf |
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| Zusammenfassung |
| Field and plasma observations from the vicinity of Europa by the Galileo spacecraft show
that Europa’s response to the corotating field and plasma impinging on it is binary in nature.
Galileo successfully encountered Europa 10 times during its mission. During nine of these
flybys, the interaction between Europa and Jupiter was observed to be fairly modest. The
modeling of magnetic data from these flybys shows that the interaction currents were in
the range of 0.5 MA and the plasma addition to the corotating flow was between
2 – 8 kg/s. However, during one of the flybys, namely E12, the field and plasma
perturbations were observed to be extremely large. During this flyby, the magnetic
field was observed to almost double in strength from its nominal value of 450 nT.
The plasma density in the environment was also extremely high during this flyby
(exceeding 800 particles/cm-3 compared to the nominal values of 50-100 particles-cm3
expected near Europa’s orbit). The energetic ion fluxes on the other hand were seen to
drop significantly in count presumably from ion losses and cooling in Europa’s
environment.
In order to understand the two interaction states of Europa observed so far,
we have now developed quantitative 3-D MHD models of plasma interactions of
Europa with Jupiter’s magnetosphere. In these models we include the effects of
plasma pick-up and plasma interaction with a realistic exosphere as well as the
contribution of the electromagnetic induction. We will present results of these quantitative
models and show that the plasma interaction is strongest when Europa is located at
the center of Jupiter’s current sheet. We find that plasma mass loading rates are
extremely variable over time. We will investigate various mechanisms by which such
variability in mass-loading could be produced including episodically enhanced
sputtering from trapped gaseous molecules in ice and enhanced plasma interaction
with a vent(s) generated dense exosphere. The new model will aid researchers in
planning observations from future missions such as JUICE and Europa flagship
mission. |
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