Letter | Published:

Liquid water on Enceladus from observations of ammonia and 40Ar in the plume

Nature volume 460, pages 487490 (23 July 2009) | Download Citation

Subjects

  • A Corrigendum to this article was published on 27 August 2009

Abstract

Jets of water ice from surface fractures near the south pole1 of Saturn’s icy moon Enceladus produce a plume of gas and particles2,3,4,5. The source of the jets may be a liquid water region under the ice shell—as suggested most recently by the discovery of salts in E-ring particles derived from the plume6—or warm ice that is heated, causing dissociation of clathrate hydrates7. Here we report that ammonia is present in the plume, along with various organic compounds, deuterium and, very probably, 40Ar. The presence of ammonia provides strong evidence for the existence of at least some liquid water, given that temperatures in excess of 180 K have been measured near the fractures from which the jets emanate8. We conclude, from the overall composition of the material, that the plume derives from both a liquid reservoir (or from ice that in recent geological time has been in contact with such a reservoir) as well as from degassing, volatile-charged ice.

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Acknowledgements

Support by the Cassini Project through a subcontract with Southwest Research Institute is acknowledged.

Author Contributions J.H.W. organized and coordinated the plume composition study. J.H.W., C.R.G., W.S.L., J.I.L., W.B.M., O.M., M.-J.N. and J.W. developed the concept of the Letter and the interpretation of the INMS data. W.S.L., J.I.L., W.B.M., C.R.G. and O.M. worked jointly to write the manuscript. B.A.M. analysed the data and prepared the spectra. D.T.Y., T.B. and B.D.T. analysed the physical and chemical interactions of the inflowing material with the INMS antechamber and, together with B.A.M. and C.R.G., prepared the Supplementary Information. H.B.N. provided calibration support and information about instrument performance. R.L.M., M.P. and W.-H.I. provided supporting analysis of the neutral and ion environment surrounding Enceladus.

Author information

Affiliations

  1. Southwest Research Institute, San Antonio, Texas 78228, USA

    • J. H. Waite Jr
    • , W. S. Lewis
    • , B. A. Magee
    • , D. T. Young
    • , T. Brockwell
    • , J. Westlake
    • , M.-J. Nguyen
    •  & B. D. Teolis
  2. Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona 85721, USA

    • J. I. Lunine
    •  & O. Mousis
  3. Department of Earth and Planetary Sciences, Washington University, St Louis, Missouri 63130, USA

    • W. B. McKinnon
  4. School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287, USA

    • C. R. Glein
  5. Observatoire de Besançon, Institut UTINAM, CNRS-UMR 6213, BP 1615, 25010 Besançon Cedex, France

    • O. Mousis
  6. NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA

    • H. B. Niemann
  7. The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland 20723, USA

    • R. L. McNutt Jr
    •  & M. Perry
  8. Institutes of Astronomy and Space Science, National Central University, Chung Li 32054, Taiwan

    • W.-H. Ip

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Corresponding author

Correspondence to W. S. Lewis.

Supplementary information

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  1. 1.

    Supplementary Information

    This file contains Supplementary Methods and Data, Supplementary Figures S1-S4, Supplementary Tables S1-S7 and Supplementary References.

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DOI

https://doi.org/10.1038/nature08153

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