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| Titel |
Ten Years of ENA Imaging from Cassini |
| VerfasserIn |
Pontus Brandt, Donald Mitchell, Joseph Westlake, James Carbary, Christopher Paranicas, Barry Mauk, Stamatios Krimigis |
| 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 |
250097110
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| Publikation (Nr.) |
 EGU/EGU2014-12658.pdf |
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| Zusammenfassung |
| In this presentation we will provide a detailed review of the science highlights of the ENA
observations obtained by The Ion Neutral Camera (INCA) on board Cassini. Since the launch
of Cassini, INCA has unveiled an invisible world of hot plasma and neutral gas of the two
biggest objects of our solar system: the giant magnetosphere of Jupiter and Saturn. Although
more than ten years ago, INCA captured the first ENA images of the Jovian system revealing
magnetospheric dynamics and an asymmetric Europa neutral gas torus. Approaching Saturn,
INCA observed variability of Saturn’s magnetospheric activity in response to changes in solar
wind dynamic pressure, which was contrary to expectations and current theories. In orbit
around Saturn, INCA continued the surprises including the first imaging and global
characterization of Titan’s exosphere extended out to its gravitational Hill sphere;
recurring injections correlating with periodic Saturn Kilometric Radiation (SKR)
bursts and magnetic field perturbations; and the discovery of energetic ionospheric
outflow.
Perhaps most significant, and the focal point of this presentation, is INCA’s contribution
to the understanding of global magnetospheric particle acceleration and transport, where the
combination between ENA imaging and in-situ measurements have demonstrated that
transport and acceleration of plasma is likely to occur in a two-step process. First, large-scale
injections in the post-midnight sector accelerate and transport plasma in to about 12 RS up to
energies of several hundreds of keV. Second, centrifugal interchange acts on the plasma
inside of this region and provides further heating and transport in to about 6RS. We
discuss this finding in the context of the two fundamental types of injections (or ENA
intensifications) that INCA has revealed during its ten years of imaging. The first type is
large-scale injections appearing beyond 12 RS in the post-midnight sector that have in many
cases had an inward component of propagation. The second type is apparently local
injections inside of about 12 RS and as far in as 6RS in the pre-midnight sector with a
recurrence period around 11h that, interestingly, appear to precede the larges-scale
injections. |
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