Liquid water on Enceladus from observations of ammonia and 40Ar in the plume (original) (raw)

Nature volume 460, pages 487–490 (2009)Cite this article

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.

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Authors and 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

Authors

  1. J. H. Waite Jr
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  2. W. S. Lewis
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  3. B. A. Magee
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  4. J. I. Lunine
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  5. W. B. McKinnon
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  6. C. R. Glein
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  7. O. Mousis
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  8. D. T. Young
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  9. T. Brockwell
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  10. J. Westlake
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  11. M.-J. Nguyen
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  12. B. D. Teolis
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  13. H. B. Niemann
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  14. R. L. McNutt Jr
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  15. M. Perry
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  16. W.-H. Ip
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Corresponding author

Correspondence toW. S. Lewis.

Supplementary information

Supplementary Information

This file contains Supplementary Methods and Data, Supplementary Figures S1-S4, Supplementary Tables S1-S7 and Supplementary References. (PDF 1491 kb)

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Waite Jr, J., Lewis, W., Magee, B. et al. Liquid water on Enceladus from observations of ammonia and 40Ar in the plume.Nature 460, 487–490 (2009). https://doi.org/10.1038/nature08153

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Editorial Summary

Messages from Enceladus

Since Cassini spacecraft images revealed plumes of water vapour and ice particles erupting from Saturn's moon Enceladus in 2006, the search for the water source has been on. Possibilities include liquid water under the ice shell and ice that is subject to heating. The chemical composition of the jets can give clues as to their source. The 9 October 2008 Cassini fly-by provides a data set ideal for the purpose — mass spectrometry with the best signal-to-noise ratio so far obtained, sufficient to allow the identification of chemicals present in trace amounts. Waite et al. use these data to reveal the presence of ammonia in the plume, strong evidence for the existence of at least some liquid water. The overall composition of the plume suggests that it arises from both a liquid reservoir (or ice derived from one) and from the degassing of ice containing volatile materials.