Saturn's Dynamic Magnetosphere: Energetic Particles and Neutrals from the Magnetospheric Imaging Instrument (MIMI)
Abstract
The MIMI investigation comprises three sensors: the Ion and Neutral Camera (INCA) provides images using energetic neutral atoms (ENA) and ions; the Charge-Energy-Mass-Spectrometer (CHEMS) determines the mass and charge state of ions; and the Low Energy Magnetospheric Measurement System (LEMMS) measures ion and electron distributions using a dual field-of-view telescope (Krimigis et al., 2004). Measurements by MIMI following Saturn orbit insertion on 1 July 2004 revealed: (1) a dynamical magnetosphere with a day-night asymmetry and an 11-hour periodicity; (2) several water-product ions (O+, OH+, H2O+), but little N+; (3) inferred quantities of neutral gas sufficient to cause major losses in the trapped ions and electrons in the middle and inner magnetosphere; (4) a Titan exosphere that is a copious source of energetic neutral atoms (ENA); (5) a previously unknown radiation belt residing inward of the D-ring that is most likely the result of double charge-exchange between the main radiation belt and the upper layers of Saturn's exosphere. Finally, MIMI data show evidence of injections of plasma on the night-side of the planet, some substorm-like in the magnetotail and others in the 7-10 RS region that subsequently corotate with the planet for a number of days before dissipating. The observations will be presented and discussed in the context of current theoretical models of Saturn's magnetosphere. Krimigis, S. M., et al., Magnetosphere Imaging Instrument (MIMI) on the Cassini Mission to Saturn/Titan, Space Sci. Rev., volume 114/1-4, pp 233-329, 2004.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2005
- Bibcode:
- 2005AGUSM.P14A..04K
- Keywords:
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- 6265 Planetary rings;
- 6275 Saturn;
- 6280 Saturnian satellites