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

A Corrigendum to this article was published on 27 August 2009


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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Figure 1: Mass spectrum on 9 October 2008.
Figure 2: Histogram showing the INMS spectrum over the mass range 34–48 Da.
Figure 3: Comparison of volatile abundances observed in Enceladus’ plume with those seen in cometary comae.

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  1. Porco, C. C. et al. Cassini observes the active south pole of Enceladus. Science 311, 1393–1401 (2006)

    Article  ADS  CAS  Google Scholar 

  2. Dougherty, M. K. et al. Identification of a dynamic atmosphere at Enceladus with the Cassini Magnetometer. Science 311, 1406–1409 (2006)

    Article  ADS  CAS  Google Scholar 

  3. Waite, J. H. et al. Cassini Ion and Neutral Mass Spectrometer: Enceladus plume composition and structure. Science 311, 1419–1422 (2006)

    Article  ADS  CAS  Google Scholar 

  4. Hansen, C. J. et al. Enceladus’ water vapor plume. Science 311, 1423–1425 (2006)

    Article  ADS  Google Scholar 

  5. Spahn, F. et al. Cassini dust measurements at Enceladus and implications for the origin of the E ring. Science 311, 1416–1418 (2006)

    Article  ADS  CAS  Google Scholar 

  6. Postberg, F. et al. Sodium salts in E-ring ice grains from an ocean below the surface of Enceladus. Nature 459, 1098–1101 (2009)

    Article  ADS  CAS  Google Scholar 

  7. Kieffer, S. W. et al. A clathrate reservoir hypothesis for Enceladus’ south polar plume. Science 314, 1764–1766 (2006)

    Article  ADS  CAS  Google Scholar 

  8. Spencer, J. et al. High spatial resolution observations of thermal emission from Enceladus’ active south pole. Eos 89 (Fall Meet. Suppl.), abstr. P23B-1372 (2008)

  9. Waite, J. H. et al. The Cassini Ion and Neutral Mass Spectrometer (INMS) investigation. Space Sci. Rev. 114, 113–231 (2004)

    Article  ADS  CAS  Google Scholar 

  10. Owen, T. On the origin of Titan’s atmosphere. Planet. Space Sci. 48, 747–752 (2000)

    Article  ADS  CAS  Google Scholar 

  11. Niemann, H. B. et al. The abundances of constituents of Titan’s atmosphere from the GCMS instrument on the Huygens probe. Nature 438, 779–784 (2005)

    Article  ADS  CAS  Google Scholar 

  12. Lopes, R. M. C. et al. Cryovolcanic features on Titan’s surface as revealed by the Cassini Titan Radar Mapper. Icarus 186, 395–412 (2007)

    Article  ADS  Google Scholar 

  13. Roberts, J. H. & Nimmo, F. Tidal heating and the long-term stability of a subsurface ocean on Enceladus. Icarus 194, 675–689 (2007)

    Article  ADS  Google Scholar 

  14. Tobie, G., Čadek, O. & Sotin, C. Solid tidal friction above a liquid water reservoir as the origin of the south pole hotspot on Enceladus. Icarus 196, 642–652 (2008)

    Article  ADS  CAS  Google Scholar 

  15. Matson, D. L., Castillo, J. C., Lunine, J. I. & Johnson, T. V. Enceladus’ plume: compositional evidence for a hot interior. Icarus 187, 569–573 (2007)

    Article  ADS  CAS  Google Scholar 

  16. Bockelée-Morvan, D., Crovisier, J., Mumma, M. J. & Weaver, H. A. in Comets II (eds Festou, M. C., Keller, H. U. & Weaver, H. A.) 391–423 (Univ. Arizona Press, 2004)

    Google Scholar 

  17. Glein, C. R., Zolotov, M. Y. & Shock, E. L. The oxidation state of hydrothermal systems on early Enceladus. Icarus 197, 157–163 (2008)

    Article  ADS  CAS  Google Scholar 

  18. Miyakawa, S. et al. The cold origin of life: A. Implications based on the hydrolytic stabilities of hydrogen cyanide and formamide. Orig. Life Evol. Biosph. 32, 195–208 (2002)

    Article  ADS  CAS  Google Scholar 

  19. Lodders, K. & Fegley, B. A Planetary Scientist’s Companion (Oxford Univ. Press, 1998)

    Google Scholar 

  20. Zolotov, M. Y. An oceanic composition on early and today’s Enceladus. Geophys. Res. Lett. 34 L23203 10.1029/2007GL031234 (2007)

    Article  ADS  Google Scholar 

  21. Meyer, J. & Wisdom, J. Tidal heating in Enceladus. Icarus 188, 235–239 (2007)

    Article  Google Scholar 

  22. Geiss, J. & Gloeckler, G. Abundances of deuterium and helium in the protosolar cloud. Space Sci. Rev. 84, 239–250 (1998)

    Article  ADS  CAS  Google Scholar 

  23. Horner, J., Mousis, O., Alibert, Y., Lunine, J. I. & Blanc, M. Constraints on the formation of icy bodies in the Jovian system and beyond. Planet. Space Sci. 56, 1585–1595 (2008)

    Article  ADS  CAS  Google Scholar 

  24. Canup, R. M. & Ward, W. R. Formation of the Galilean satellites: conditions of accretion. Astron. J. 124, 3404–3423 (2002)

    Article  ADS  Google Scholar 

  25. Mousis, O. et al. Clathration of volatiles in the solar nebula and implications for the origin of Titan's atmosphere. Astrophys. J. 691, 1780–1786 (2009)

    Article  ADS  CAS  Google Scholar 

  26. Shock, E. L. & McKinnon, W. B. Hydrothermal processing of cometary volatiles: applications to Triton. Icarus 106, 464–477 (1993)

    Article  ADS  CAS  Google Scholar 

  27. Hansen, C. J. et al. Water vapour jets inside the plume of gas leaving Enceladus. Nature 456, 477–479 (2008)

    Article  ADS  CAS  Google Scholar 

  28. Schmidt, J., Brillantov, N., Spahn, F. & Kempf, S. Slow dust in Enceladus' plume from condensation and wall collisions in tiger stripe fractures. Nature 451, 685–688 (2008)

    Article  ADS  CAS  Google Scholar 

  29. Nimmo, F., Spencer, J. R., Pappalardo, R. T. & Mullen, M. E. Shear heating as the origin of the plumes and heat flux on Enceladus. Nature 447, 289–291 (2007)

    Article  ADS  CAS  Google Scholar 

  30. Fortes, A. D. Metasomatic clathrate xenoliths as a possible source for the south polar plumes of Enceladus. Icarus 191, 743–748 (2007)

    Article  ADS  Google Scholar 

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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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Correspondence to W. S. Lewis.

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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).

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