Huygens Letters

Nature 438, 796-799 (8 December 2005) | doi:10.1038/nature04349; Received 27 May 2005; Accepted 20 October 2005; Published online 30 November 2005

Complex organic matter in Titan's atmospheric aerosols from in situ pyrolysis and analysis

G. Israël1, C. Szopa1, F. Raulin2, M. Cabane1, H. B. Niemann3, S. K. Atreya4, S. J. Bauer5, J.-F. Brun1, E. Chassefière1, P. Coll2, E. Condé6, D. Coscia2, A. Hauchecorne1, P. Millian7, M.-J. Nguyen2, T. Owen8, W. Riedler9, R. E. Samuelson10, J.-M. Siguier7, M. Steller11, R. Sternberg2 & C. Vidal-Madjar12

Aerosols in Titan's atmosphere play an important role in determining its thermal structure1, 2, 3. They also serve as sinks for organic vapours4 and can act as condensation nuclei for the formation of clouds5, 6, where the condensation efficiency will depend on the chemical composition of the aerosols5, 7. So far, however, no direct information has been available on the chemical composition of these particles. Here we report an in situ chemical analysis of Titan's aerosols by pyrolysis at 600 °C. Ammonia (NH3) and hydrogen cyanide (HCN) have been identified as the main pyrolysis products. This clearly shows that the aerosol particles include a solid organic refractory core. NH3 and HCN are gaseous chemical fingerprints of the complex organics that constitute this core, and their presence demonstrates that carbon and nitrogen are in the aerosols.

  1. Service d'Aéronomie UMR 7620 CNRS, ISPL, Universities Paris 6 and Versailles-Saint Quentin, Verrières-le-Buisson, F 91371, France
  2. Laboratoire Interuniversitaire des Systèmes Atmosphériques, UMR 7583 CNRS, Universities Paris 12 and Paris 7, Créteil, F 94010, France
  3. NASA Goddard Space Flight Centre, Greenbelt, Maryland 20771, USA
  4. University of Michigan, Ann Arbor , Michigan 48109, USA
  5. Institute for Meteorology and Geophysics, University of Graz, Graz A 8010, Austria
  6. Centre National d'Etudes Spatiales (CNES), Toulouse, F 31401, France
  7. Office National d'Etudes et de Recherches Aérospatiales, Toulouse, F 31055, France
  8. Institute for Astronomy, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA
  9. Space Research Institute, Graz A 8010, Austria
  10. Department of Astronomy, University of Maryland, College Park, Maryland 20742, USA
  11. Institut für Weltraumforschung, Österreichische Akademie der Wissenschaften, Graz A 8042, Austria
  12. Laboratoire de Recherche sur les Polymères, UMR 7581 CNRS, Thiais, F 94320, France

Correspondence to: G. Israël1 Correspondence and requests for materials should be addressed to G.I. (Email:


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