The structure of Titan's ionosphere: model comparisons with Cassini data
Abstract
Solar extreme ultraviolet and x-ray radiation and energetic plasma from Saturn's magnetosphere interact with the upper atmosphere producing an ionosphere at Titan. The highly coupled ionosphere and upper atmosphere system mediates the interaction between Titan and the external environment. New insights into Titan's ionosphere are being facilitated by data from several instruments onboard the Cassini Orbiter, although the Ion and Neutral Mass Spectrometer (INMS) measurements will be emphasized in this talk. Measurements and comparisons with a model will be discussed for both the day and night on Titan. Electron impact ionization associated with precipitation of magnetospheric electrons (measured by the electron sensor on the CAPS spectrometer) seems the likely explanation for the nightside ionosphere but photoionization by solar radiation is the dominant source on the dayside. In this talk we will emphasize possible explanations for the temporal and/or spatial structure observed by the INMS and RPWS/LP (Radio and Plasma Wave – Langmuir probe) experiments during the T5 nightside pass, suggesting that temporal changes in the incident magnetospheric electron flux might be responsible for much of this structure.