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| Titel |
The exosphere of Europa: role of photolysis and radiolysis |
| VerfasserIn |
Christina Plainaki, Anna Milillo, Alessandro Mura, Stefano Orsini, Stefano Massetti |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250054734
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| Zusammenfassung |
| The exosphere of Europa is the result of different surface release processes and
subsequent modification of the released particles. The main constituent of the icy
surface is water with minor portion of heavy water (H2O2) and other impurities.
This means that probably the major released species is H2O. Nevertheless, the
released particles experience photolysis and radiolysis due to solar UV and Jupiter’s
magnetospheric plasma respectively. The initial photolysis species in ice are OH, H and
O, with the possibility of H2. These dissociated species can react to reform water
and/or new species: H2, H2O2, O2 and HO2. At the end, the components of the
Europa exosphere are a mixture of these different molecules. In fact, the Hubble
Space Telescope observations, initially, revealed the existence of a tenuous O2
atmosphere with a column density of about (0.24-1.4) 1015 cm-2, whereas, later,
the Ultraviolet Imaging Spectrograph on the Cassini, during its flyby of Jupiter,
confirmed this discovery. In this work, starting from previously developed MC model
for the generation of Europa’s exosphere, where the only considered species was
water, we make a first attempt to simulate the more realistic atmosphere of Europa,
mainly consisting of O2 and O. We compare the results of this analysis with those
obtained by other models and with the in situ measurements and discuss them. |
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