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| Titel |
Generation of an exosphere around an icy moon: the case of Europa |
| VerfasserIn |
C. Plainaki, A. Milillo, A. Mura, S. Orsini, S. Massetti, T. Cassidy |
| 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 |
250062399
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| Zusammenfassung |
| The exosphere of an icy moon with a tenuous or without atmosphere is the result of different
surface release processes and subsequent modification of the released particles. Water ice is
directly released, but photolysis and radiolysis due to solar UV and magnetospheric plasma,
respectively, can result in OH, H, O and (possibly) H2 production. These molecules can
recombine to reform water and/or new chemical species. As a consequence, the neutral
environment of Jupiter’s icy moon Europa becomes a mixture of different molecules,
among which, H2O dominates in the highest altitudes and O2, formed mainly by
radiolysis of ice and subsequent release of the produced molecules, prevails at lower
altitudes. In this work we present a Monte Carlo model that simulates the exosphere
generation processes at the Europa icy moon and we calculate the escape of H2O,
O2 and H2. We show that different configurations between the moon’s leading
hemisphere and the Sun’s position influence the exosphere spatial distribution. We
also make an estimation of the sputtered H2O exosphere of this moon, taking into
consideration the trailing-leading asymmetry in the magnetospheric ion bombardment
and the energy and temperature dependences of the process yields. We find that a
density of about 1.5-
1012 H2O/m3 is expected at altitudes about 0.1 RE above the
surface of the trailing hemisphere. The estimations obtained by this study provide
useful information for the preparation of future missions at the Jupiter’s moons. |
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