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| Titel |
Temperature variations in Titan's upper atmosphere: Impact on Cassini/Huygens |
| VerfasserIn |
B. Kazeminejad, H. Lammer, A. Coustenis, O. Witasse, G. Fischer, K. Schwingenschuh, A. J. Ball, H. O. Rucker |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 23, no. 4 ; Nr. 23, no. 4 (2005-06-03), S.1183-1189 |
| Datensatznummer |
250015214
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| Publikation (Nr.) |
 copernicus.org/angeo-23-1183-2005.pdf |
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| Zusammenfassung |
| Temperature variations of Titan's upper atmosphere due to the plasma
interaction of the satellite with Saturn's magnetosphere and Titan's
high altitude monomer haze particles can imply an offset of up to
±30K from currently estimated model profiles. We incorporated
these temperature uncertainties as an offset into the recently
published Vervack et al. (2004) (Icarus, Vol. 170, 91-112)
engineering model and derive extreme case (i.e. minimum and maximum
profiles) temperature, pressure, and density profiles. We simulated
the Huygens probe hypersonic entry trajectory and obtain, as
expected, deviations of the probe trajectory for the extreme
atmosphere models compared to the simulation based on the nominal one.
These deviations are very similar to the ones obtained with the
standard Yelle et al. (1997) (ESA SP-1177) profiles. We
could confirm that the difference in aerodynamic drag is of an
order of magnitude that can be measured by the probe science
accelerometer. They represent an important means for the
reconstruction of Titan's upper atmospheric properties. Furthermore,
we simulated a Cassini low Titan flyby trajectory. No major
trajectory deviations were found. The atmospheric torques due to
aerodynamic drag, however, are twice as high for our high temperature
profile as the ones obtained with the Yelle maximum profile and more
than 5 times higher than the worst case estimations from the Cassini
project. We propose to use the Cassini atmospheric torque
measurements during its low flybys to derive the atmospheric drag
and to reconstruct Titan's upper atmosphere density, pressure, and
temperature. The results could then be compared to the reconstructed
profiles obtained from Huygens probe measurements. This would help
to validate the probe measurements and decrease the error bars. |
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