Titan's and Saturn's exospheres: first MIMI energetic neutral atom observations
Publication date: 28 May 2005
Authors: Dandouras, I., et al.
Journal: AGU, Spring Meeting 2005, abstract #P33A-01
Titan's nitrogen-rich atmosphere is directly bombarded by energetic ions, due to its lack of a significant intrinsic magnetic field. Singly-charged energetic ions from Saturn's magnetosphere undergo charge exchange collisions with neutral atoms in Titan's exosphere, being transformed into energetic neutral atoms (ENAs). The Ion and Neutral Camera (INCA), one of the three sensors that comprise the Magnetosphere Imaging Instrument (MIMI) on the Cassini/Huygens mission to Saturn and Titan, images the ENA emissions from various ion/gas interaction regions in the Saturnian magnetosphere. During Cassini's second orbit around Saturn the spacecraft performed the Ta Titan flyby (October 26, 2004), at an altitude of only 1174 km. INCA data acquired during this targeted close flyby confirm model predictions of dominant finite ion gyroradii effects, but also reveal a much more complex interaction: maximum ENA emissions are originating at higher altitudes than predicted by a simple Chamberlain-type model of the Titan exosphere. These observations will be analyzed and a simulation will be presented of some of the exospheric features they reveal.