The Cassini Huygens mission has revealed a versatile ion chemistry in the upper layers of Titan’s atmosphere. The Ion Neutral Mass spectrometer (INMS) identified a multitude of nitrogen-containing ions, and the CAPS spectrometer detected an unexpectedly high density of large anions, whose density greatly varies with the solar zenith angle. Whereas there have been considerable research efforts into relevant cation reactions, many production and destruction processes of ionic species are still accounted for. Moreover, chemical models fail to predict the abundances of several important ionic species. New findings from Cassini-Huygens and novel experimental results will be presented and remaining open questions about the ion chemistry in Titan’s atmosphere discussed.
