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A salt-water reservoir as the source of a compositionally stratified plume on Enceladus

Nature volume 474, pages 620–622 (2011)Cite this article

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Abstract

The discovery of a plume of water vapour and ice particles emerging from warm fractures (‘tiger stripes’) in Saturn's small, icy moon Enceladus1,2,3,4,5,6 raised the question of whether the plume emerges from a subsurface liquid source6,7,8 or from the decomposition of ice9,10,11,12. Previous compositional analyses of particles injected by the plume into Saturn's diffuse E ring have already indicated the presence of liquid water8, but the mechanisms driving the plume emission are still debated13. Here we report an analysis of the composition of freshly ejected particles close to the sources. Salt-rich ice particles are found to dominate the total mass flux of ejected solids (more than 99 per cent) but they are depleted in the population escaping into Saturn's E ring. Ice grains containing organic compounds are found to be more abundant in dense parts of the plume. Whereas previous Cassini observations were compatible with a variety of plume formation mechanisms, these data eliminate or severely constrain non-liquid models and strongly imply that a salt-water reservoir with a large evaporating surface7,8 provides nearly all of the matter in the plume.

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Figure 1: Proportions of particles of different spectral type detected during the central period of the E5 fly-by.
Figure 2: Modelling of the E5 measurements.
Figure 3: Compositional and size profile of the ice plume.

References

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

    ADS  CAS  Article  Google Scholar 

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

    ADS  CAS  Article  Google Scholar 

  3. Hansen, C. J. et al. Enceladus' water vapor plume. Science 311, 1422–1425 (2006)

    ADS  CAS  Article  Google Scholar 

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

    ADS  CAS  Article  Google Scholar 

  5. Spencer, J. R. et al. Cassini encounters Enceladus: background and the discovery of a south polar hot spot. Science 311, 1401–1405 (2006)

    ADS  CAS  Article  Google Scholar 

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

    ADS  CAS  Article  Google Scholar 

  7. 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)

    ADS  CAS  Article  Google Scholar 

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

    ADS  CAS  Article  Google Scholar 

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

    ADS  CAS  Article  Google Scholar 

  10. Gioia, G., Chakraborty, P., Marshak, S. & Kieffer, W. Unified model of tectonics and heat transport in a frigid Enceladus. Proc. Natl Acad. Sci. USA 104, 13578–13581 (2007)

    ADS  CAS  Article  Google Scholar 

  11. 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)

    ADS  CAS  Article  Google Scholar 

  12. Kieffer, S. et al. A redetermination of the ice/vapor ratio of Enceladus’ plumes: implications for sublimation and the lack of a liquid water reservoir. Icarus 203, 238–241 (2009)

    ADS  CAS  Article  Google Scholar 

  13. Schneider, N. M. et al. No sodium in the vapour plumes of Enceladus. Nature 459, 1102–1104 (2009)

    ADS  CAS  Article  Google Scholar 

  14. Srama, R. et al. The Cassini cosmic dust analyzer. Space Sci. Rev. 114, 465–518 (2004)

    ADS  CAS  Article  Google Scholar 

  15. Hillier, J. K. et al. The composition of Saturn's E ring. Mon. Not. R. Astron. Soc. 388, 1588–1596 (2007)

    ADS  Article  Google Scholar 

  16. Postberg, F. et al. The E-ring in the vicinity of Enceladus II. Probing the moon’s interior — the composition of E-ring particles. Icarus 193, 438–454 (2008)

    ADS  CAS  Article  Google Scholar 

  17. Zolotov, M. Y. An oceanic composition on early and today's Enceladus. Geophys. Res. Lett. 34, L23203 (2007)

    ADS  Article  Google Scholar 

  18. Kempf, S. et al. Enceladus dust production — new insights from Cassini. Am. Geophys. Union Fall Meet. abstr. P33A–1562. (2010)

  19. Hedman, M. et al. Spectral observations of the Enceladus plume with Cassini-VIMS. Astrophys. J. 693, 1749–1762 (2009)

    ADS  Article  Google Scholar 

  20. Sremcevic, M. et al. Impact-generated dust clouds around planetary satellites: asymmetry effects. Planet. Space Sci. 51 (issue 7–8). 455–471 (2003)

    ADS  Article  Google Scholar 

  21. Hansen, C. J. et al. The composition and structure of the Enceladus plume. Geophys. Res. Lett. 38, L11202 (2011)

    ADS  Article  Google Scholar 

  22. Spitale, J. N. & Porco, C. C. Association of jets on Enceladus with the warmest regions on its south-polar fractures. Nature 449, 695–697 (2007)

    ADS  CAS  Article  Google Scholar 

  23. Halevy, I. & Stewart, S. T. Is Enceladus' plume tidally controlled? Geophys. Res. Lett. 35 L12203 10.1029/2008GL034349 (2008)

    ADS  Article  Google Scholar 

  24. Waite, J. H. et al. Liquid water on Enceladus from observations of ammonia and 40Ar in the plume. Nature 460, 487–490 (2009)

    ADS  CAS  Article  Google Scholar 

  25. Waite, J. H., Jr, Magee, B. & Brockwell, T. The effect of flyby velocity on the composition of the Enceladus gas torus as measured by Cassini INMS. Proc. Lunar Planet. Sci. Conf. 42, 2818 (2011)

    ADS  Google Scholar 

  26. Tian, F., Stewart, A. I. F., Toon, O. B., Larsen, K. W. & Esposito, L. W. Monte Carlo simulations of water vapour plumes on Enceladus. Icarus 188, 154–161 (2007)

    ADS  CAS  Article  Google Scholar 

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Acknowledgements

We thank G. Moragas-Klostermeyer and S. Helfert for their efforts in preparing the CDA plume observations. We acknowledge the work of the scientists and engineers of the Cassini Team at JPL. This work was supported by Deutsches Zentrum für Luft und Raumfahrt (DLR) and Deutsche Forschungs Gemeinschaft (DFG programme ‘The first 10 million years of the solar system’). J.H. was supported by the UK Science and Technology Facilities Council.

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Authors and Affiliations

  1. Institut für Geowissenschaften, Universität Heidelberg, 69120 Heidelberg, Germany ,

    F. Postberg

  2. Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany

    F. Postberg, S. Kempf & R. Srama

  3. Institut für Physik und Astronomie, Universität Potsdam, 14476 Potsdam-Golm, Germany ,

    J. Schmidt

  4. Planetary and Space Sciences Research Institute, The Open University, Milton Keynes MK7 6AA, UK ,

    J. Hillier

  5. IGEP,Technische Universität Braunschweig, 38106 Braunschweig, Germany ,

    S. Kempf

  6. LASP, University of Colorado, Boulder, 80303, Colorado, USA

    S. Kempf

  7. IRS, Universität Stuttgart, 70569 Stuttgart, Germany ,

    R. Srama

Authors
  1. F. Postberg
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  2. J. Schmidt
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  3. J. Hillier
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  4. S. Kempf
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  5. R. Srama
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Contributions

F.P. led the analysis and write-up of the manuscript. J.S. led the dynamical modelling and contributed to data analysis and text. J.H. and S.K. contributed to data analysis and text. S.K. and R.S. designed the CDA plume measurement.

Corresponding author

Correspondence to F. Postberg.

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The authors declare no competing financial interests.

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Postberg, F., Schmidt, J., Hillier, J. et al. A salt-water reservoir as the source of a compositionally stratified plume on Enceladus. Nature 474, 620–622 (2011). https://doi.org/10.1038/nature10175

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