INMS-derived composition of Titan's upper atmosphere: Analysis methods and model comparison

The Cassini Ion and Neutral Mass Spectrometer (INMS) has recorded full altitude profile data from 20 low-altitude Titan encounters during the nominal mission (July 2004-2008). These encounters were TA. T5, T16, T18, T19, T21, T23, T25, T26, T28, T29, T30, T32. T36, T37, T39, T40, T41, T42, and T43. In this work we present an analysis of the data observed by INMS during these encounters to derive the neutral composition of Titan's upper atmosphere between 1000 and 1100 km. Analysis methods are described for the determination and correction of instrument effects as well as the composition derivation processes. Results are compared to independent INMS analysis efforts and a selected survey of photochemical models of Titan's upper atmosphere. (C) 2009 Elsevier Ltd. All rights reserved.