Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Huygens Letters
  • Published:

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

Abstract

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.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Signal resulting from the mass spectrometry (MS) analysis of the gases evolved from pyrolysis of the first aerosol sample.
Figure 2: Signal resulting from the MS analysis of the gases evolved from pyrolysis of the second aerosol sample.
Figure 3: Temporal evolution of the intensity of the MS signatures attributed to ammonia for the second aerosol sample pyrolysis.

Similar content being viewed by others

References

  1. McKay, C. P., Pollack, J. B. & Courtin, R. The greenhouse and antigreenhouse effects on Titan. Science 253, 1118–1121 (1991)

    Article  ADS  CAS  PubMed  Google Scholar 

  2. Rannou, P., Hourdin, F., McKay, C. P. & Luz, D. A coupled dynamics-microphysics model of Titan's atmosphere. Icarus 170, 443–462 (2004)

    Article  ADS  Google Scholar 

  3. DelGenio, A. D., Zhou, W. & Eichler, T. P. Equatorial superrotation in a slowly rotating GCM — Implications for Titan and Venus. Icarus 101, 1–17 (1993)

    Article  ADS  Google Scholar 

  4. Lebonnois, S., Bakes, E. L. O. & McKay, C. P. Transition from gaseous compounds to aerosols in Titan's atmosphere. Icarus 159, 505–517 (2002)

    Article  ADS  CAS  Google Scholar 

  5. Barth, E. L. & Toon, O. W. Properties of methane clouds on Titan: results from microphysical modelling. Geophys. Res. Lett. 31, L17S07 (2004)

    Google Scholar 

  6. Mayo, L. A. & Samuelson, R. E. Condensate clouds in Titan's north polar stratosphere. Icarus 176, 316–330 (2005)

    Article  ADS  Google Scholar 

  7. McKay, C. P. et al. Physical properties of the organic aerosols and clouds of Titan. Planet. Space Sci. 49, 79–99 (2001)

    Article  ADS  CAS  Google Scholar 

  8. Niemann, H. et al. The abundances of constituents of Titan's atmosphere from the GCMS instrument on the Huygens probe. Nature doi:10.1038/nature04122 (this issue)

  9. Israel, G., Cabane, M., Raulin, F., Chassefière, E. & Boon, J. J. Aerosols in Titan's atmosphere: models, sampling techniques and chemical analysis. Ann. Geophys. 9, 1–13 (1991)

    ADS  CAS  Google Scholar 

  10. Israel, G. et al. Huygens Probe Aerosol Collector Pyrolyser Experiment. Space Sci. Rev. 104, 435–466 (2002)

    Article  ADS  Google Scholar 

  11. Niemann, H. et al. The Gas Chromatograph Mass Spectrometer for the Huygens Probe. Space Sci. Rev. 104, 551–590 (2002)

    Article  ADS  Google Scholar 

  12. Wilson, E. H. & Atreya, S. K. Chemical sources of haze formation in Titan's atmosphere. Planet. Space Sci. 51, 1017–1033 (2003)

    Article  ADS  CAS  Google Scholar 

  13. Chang, S., DesMarais, D., Mack, R., Miller, S. L. & Strathearn, G. E. in Earth's Earliest Biosphere: Its Origin and Evolution (ed. Schopf, J. W.) 53–92 (Princeton Univ. Press, Princeton, 1982)

    Google Scholar 

  14. Bar-Nun, A., Kleinfeld, I. & Ganor, E. Shape and optical properties of aerosols formed by photolysis of acetylene, ethylene and hydrogen cyanide. J. Geophys. Res. 93, 8383–8387 (1988)

    Article  ADS  CAS  Google Scholar 

  15. Clarke, D. W. & Ferris, J. P. Titan haze: structure and properties of cyanoacetylene and cyanoacetylene-acetylene photopolymers. Icarus 127, 158–172 (1997)

    Article  ADS  CAS  PubMed  Google Scholar 

  16. Khare, B. N. et al. Optical constants of organic tholins produced in a simulated titanian atmosphere: from X-ray to microwave frequencies. Icarus 60, 127–137 (1984)

    Article  ADS  CAS  Google Scholar 

  17. Coll, P. et al. Experimental laboratory simulation of Titan's atmosphere: aerosols and gas phase. Planet. Space Sci. 47, 1331–1340 (1999)

    Article  ADS  CAS  Google Scholar 

  18. Imanaka, H. et al. Laboratory experiments of Titan tholins formed in cold plasma at various pressures: implications for nitrogen containing polycyclic aromatic compounds in Titan haze. Icarus 168, 344–366 (2004)

    Article  ADS  CAS  Google Scholar 

  19. Khare, B. N. et al. The organic aerosols of Titan. Adv. Space Res. 4, 59–68 (1984)

    Article  ADS  CAS  Google Scholar 

  20. Coll, P., Coscia, D., Gazeau, M.-C., Guez, L. & Raulin, F. Review and latest results of laboratory investigations of Titan's aerosols. Orig. Life Evol. Biosph. 28, 195–213 (1997)

    Article  ADS  Google Scholar 

  21. Ehrenfreund, P. et al. Analytical pyrolysis experiments of Titan aerosol analogues in preparation for the Cassini Huygens mission. Adv. Space Res. 15, 335–342 (1995)

    Article  ADS  CAS  PubMed  Google Scholar 

  22. Somogyi, A., Oh, C.-H., Smith, M. A. & Lunine, J. I. Organic environments on Saturn's moon, Titan: simulating chemical reactions and analysing products by FT-ICR and ion trap mass spectrometry. J. Am. Soc. Mass Spectrom. 16, 850–859 (2005)

    Article  CAS  PubMed  Google Scholar 

  23. Thompson, W. R., Henry, T. J., Schwartz, J. M., Khare, B. N. & Sagan, C. Plasma discharge in N2 + CH4 at low pressures: experimental results and applications to Titan. Icarus 90, 57–73 (1991)

    Article  ADS  CAS  PubMed  Google Scholar 

  24. Minard, R. D., Hatcher, P. G., Gourley, R. C. & Matthews, C. N. Structural investigations of hydrogen cyanide polymers: new insights using TMAH thermochemolysis/GC-MS. Orig. Life Evol. Biosph. 28, 461–473 (1998)

    Article  ADS  CAS  PubMed  Google Scholar 

  25. McKay, C. P. Elemental composition, solubility, and optical properties of Titan's organic haze. Planet. Space Sci. 44, 741–747 (1996)

    Article  ADS  CAS  Google Scholar 

  26. Tomasko, M. G. et al. Rain, winds and haze during the Huygens probe's descent to Titan's surface. Nature doi:10.1038/nature04126 (this issue)

Download references

Acknowledgements

We acknowledge financial support from CNES, CNRS, the Austrian Ministry of Research and NASA. For the fabrication and qualification of ACP's mechanical and pneumatic components, the prime industrial contractor was SNECMA, and we acknowledge CNES Toulouse who strongly supported the CNRS ACP team. In particular, we thank C. Gelas, R. Salomé and E. Condé. We also thank the other main contractors, The Joanneum Research Institute and Austrian Aerospace, for the quality of their work. We acknowledge the support of the following people during the development of the instrument: M.-C. Gazeau and the LISA team at Créteil, R. Sablé and the ONERA/CERT in Toulouse, C. Cordelle and F. Marchandise at SNECMA, and G. Zeynard at Austrian Aerospace. We are also much indebted to the ESA Huygens Project Team for its constant support.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to G. Israël.

Ethics declarations

Competing interests

Reprints and permissions information is available at npg.nature.com/reprintsandpermissions. The authors declare no competing financial interests.

Supplementary information

Supplementary Notes

This file contains Supplementary Methods and Supplementary Figures 1–6. (DOC 673 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Israël, G., Szopa, C., Raulin, F. et al. Complex organic matter in Titan's atmospheric aerosols from in situ pyrolysis and analysis. Nature 438, 796–799 (2005). https://doi.org/10.1038/nature04349

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature04349

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing