In situ measurements of the physical characteristics of Titan's environment
Neubauer, F. M.; Rodrigo, R.; Barucci, M. A.; Debei, S.; López-Moreno, J. J.; Fulchignoni, M.; Leese, M. R.; Hathi, B.; Zarnecki, J. C.; Coustenis, A.; Bar-Nun, A.; Withers, P.; Colombatti, G.; Ferri, F.; Ball, A. J.; Bettanini, C.; Gaborit, V.; Harri, A. M.; Towner, M. C.; Angrilli, F.; Saggin, B.; Flamini, E.; McKay, C. P.; McDonnell, J. A. M.; Mäkinen, T.; Svedhem, H.; Bianchini, G.; Hamelin, M.; Schwingenschuh, K.; Grard, R.; Simões, F.; Tokano, T.; Trautner, R.; Falkner, P.; Coradini, M.; Jernej, I.; Borucki, W.; Pirronello, V.; Seiff, A.; Fanti, G.; Lehto, A.; Lion Stoppato, P. F.; Molina-Cuberos, G.
Abstract
On the basis of previous ground-based and fly-by information, we knew that Titan's atmosphere was mainly nitrogen, with some methane, but its temperature and pressure profiles were poorly constrained because of uncertainties in the detailed composition. The extent of atmospheric electricity (`lightning') was also hitherto unknown. Here we report the temperature and density profiles, as determined by the Huygens Atmospheric Structure Instrument (HASI), from an altitude of 1,400km down to the surface. In the upper part of the atmosphere, the temperature and density were both higher than expected. There is a lower ionospheric layer between 140km and 40km, with electrical conductivity peaking near 60km. We may also have seen the signature of lightning. At the surface, the temperature was 93.65 +/- 0.25K, and the pressure was 1,467 +/- 1hPa.