The vertical profile of winds on Titan (original) (raw)

Nature volume 438, pages 800–802 (2005)Cite this article

Abstract

One of Titan's most intriguing attributes is its copious but featureless atmosphere. The Voyager 1 fly-by and occultation in 1980 provided the first radial survey of Titan's atmospheric pressure and temperature1,2 and evidence for the presence of strong zonal winds3. It was realized that the motion of an atmospheric probe could be used to study the winds, which led to the inclusion of the Doppler Wind Experiment4 on the Huygens probe5. Here we report a high resolution vertical profile of Titan's winds, with an estimated accuracy of better than 1 m s-1. The zonal winds were prograde during most of the atmospheric descent, providing in situ confirmation of superrotation on Titan. A layer with surprisingly slow wind, where the velocity decreased to near zero, was detected at altitudes between 60 and 100 km. Generally weak winds (∼1 m s-1) were seen in the lowest 5 km of descent.

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Figure 1: Zonal wind velocity during the Huygens mission.

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Figure 2: Titan zonal wind height profile.

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Acknowledgements

This Letter presents results of a research project partially funded by the Deutsches Zentrum für Luft- und Raumfahrt (DLR). Parts of the research described here were carried out by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA, and by NASA's Goddard Institute for Space Studies. We thank R. Kohl, K.-P. Wagner and M. Heyl for their efforts during the DWE development programme. We appreciate the support provided by the National Radio Astronomy Observatory (NRAO) and the Australia Telescope National Facility (ATNF). NRAO is operated by Associated Universities, Inc., under a cooperative agreement with the NSF. The ATNF, managed by the Commonwealth Scientific and Industrial Research Organization (CSIRO), is funded by the Commonwealth of Australia.

Author information

Authors and Affiliations

  1. Radioastronomisches Institut, Universität Bonn, Auf dem Hügel 71, 53125, Bonn, Germany
    M. K. Bird, R. Dutta-Roy & Y. Dzierma
  2. NASA Goddard Institute for Space Studies, 2880 Broadway, New York, 10025, New York, USA
    M. Allison
  3. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, California, 91109, Pasadena, USA
    S. W. Asmar, W. M. Folkner, D. V. Johnston & R. A. Preston
  4. Department of Electrical & Computer Engineering, University of Idaho, Idaho, 83844-1023, Moscow, USA
    D. H. Atkinson
  5. Computer Engineering, University of Idaho,
    D. H. Atkinson
  6. Joint Institute for VLBI in Europe, PO Box 2, 7990, AA Dwingeloo, The Netherlands
    I. M. Avruch, L. I. Gurvits & S. V. Pogrebenko
  7. Institut für HF-Technik, Universität Bochum, 44780, Bochum, Germany
    P. Edenhofer
  8. Elektrotechnisches Institut, Technische Universität Dresden, 01062, Dresden, Germany
    D. Plettemeier
  9. Center for Radar Astronomy, Stanford University, California, 94305, Stanford, USA
    G. L. Tyler

Authors

  1. M. K. Bird
  2. M. Allison
  3. S. W. Asmar
  4. D. H. Atkinson
  5. I. M. Avruch
  6. R. Dutta-Roy
  7. Y. Dzierma
  8. P. Edenhofer
  9. W. M. Folkner
  10. L. I. Gurvits
  11. D. V. Johnston
  12. D. Plettemeier
  13. S. V. Pogrebenko
  14. R. A. Preston
  15. G. L. Tyler

Corresponding author

Correspondence toM. K. Bird.

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

Supplementary information

Supplementary Notes (download PDF )

This file contains the Supplementary Discussion, Supplementary Figures 1–3, Supplementary Tables 1–2. Supplementary Figure 1 details Huygens signal frequency measurements at the Green Bank and Parkes radio telescopes. Supplementary Figure 2 presents Huygens frequency measurements and predictions at the Green Bank Telescope. Supplementary Figure 3 details Huygens frequency measurements and predictions at the Parkes Telescope. Supplementary Table 1 lists radio telescopes participating in the Earth-based DWE network. Supplementary Table 2 presents the Radio link budget: Huygens-to-Green Bank Telescope. (PDF 70 kb)

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Bird, M., Allison, M., Asmar, S. et al. The vertical profile of winds on Titan.Nature 438, 800–802 (2005). https://doi.org/10.1038/nature04060

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Editorial Summary

New views of Titan

The Huygens probe landed on Titan on 14 January this year, and seven papers published in this issue record the encounter. They describe a world that resembles a primitive Earth, complete with weather systems and geological activity. The ‘Huygens on Titan’ section opens with an overview of the descent and landing and a News and Views piece. Tomasko et al. describe the dry riverbed and drainage channels seen during Huygens' descent, evidence that liquid methane falls as rain or erupts from cryovolcanoes, periodically flooding the surface. This paper includes the images used on the cover to the Huygens section. Niemann et al. measured the abundances of isotopes of argon, nitrogen and carbon in the atmosphere, and conclude that there is no evidence that Titan's methane comes from biological activity. Fulchignoni et al. obtained precise measurements of temperature and pressure from the upper atmosphere right down to the surface. On the way down Huygens recorded evidence for lightning. Zarnecki et al. report that the probe landed on a relatively smooth surface of icy grains with the consistency of wet clay or sand. Isräl et al. report that the aerosols in Titan's clouds have solid cores made from complex organic molecules containing carbon and nitrogen. And Bird et al. found that on average Titan's winds blow in the same direction as the moon rotates, and that close to the surface these winds are very weak, travelling at around walking speed.