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Evidence for a subsurface ocean on Europa

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Abstract

Ground-based spectroscopy of Jupiter's moon Europa, combined with gravity data, suggests that the satellite has an icy crust roughly 150 km thick and a rocky interior1,2,3,4. In addition, images obtained by the Voyager spacecraft revealed that Europa's surface is crossed by numerous intersecting ridges and dark bands (called lineae) and is sparsely cratered, indicating that the terrain is probably significantly younger than that of Ganymede and Callisto5. It has been suggested that Europa's thin outer ice shell might be separated from the moon's silicate interior by a liquid water layer, delayed or prevented from freezing by tidal heating6,7,8,9,10; in this model, the lineae could be explained by repetitive tidal deformation of the outer ice shell11,12,13. However, observational confirmation of a subsurface ocean was largely frustrated by the low resolution (>2 km per pixel) of the Voyager images14. Here we present high-resolution (54 m per pixel) Galileo spacecraft images of Europa, in which we find evidence for mobile ‘icebergs’. The detailed morphology of the terrain strongly supports the presence of liquid water at shallow depths below the surface, either today or at some time in the past. Moreover, lower-resolution observations of much larger regions suggest that the phenomena reported here are widespread.

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Figure 1: Disrupted zone at 13° N, 273° W.
Figure 2: Detail from an area of mottled terrain 95 km across, just to the northeast of the area shown in Fig. 1.
Figure 3: Detail of part of the lower left quadrant of Fig. 1.

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Authors and Affiliations

  1. US Geological Survey, 345 Middlefield Road, Menlo Park, 94025, California, USA

    Michael H. Carr

  2. National Optical Astronomy Observatory, 950 Cherry Street, Tucson, 85719, Arizona, USA

    Michael J. S. Belton

  3. Southwest Research Institute, 1050 Walnut Street, Boulder, 8030, Colorado, USA

    Clark R. Chapman

  4. Rand Corporation, 1700 Main Street, Santa Monica, 90406, California, USA

    Merton E. Davies

  5. Lunar and Planetary Laboratory, University of Arizona, Tucson, 85721, Arizona, USA

    Paul Geissler, Richard Greenberg, Alfred S. McEwen & Bruce R. Tufts

  6. Geology Department, Arizona State University, Tempe, 85287, Arizona, USA

    Ronald Greeley

  7. Cornell University, Ithaca, 14853, New York, USA

    Robert Sullivan, Joseph A. Burns, Peter Thomas & Joseph Veverka

  8. Geology Department, Brown University, Providence, 02912, Rhode Island, USA

    James W. Head & Robert T. Pappalardo

  9. Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, 911909, California, USA

    Kenneth P. Klaasen, Torrence V. Johnson, James Kaufman & David Senske

  10. NASA/Ames Research Center, Moffet Field, 94035, California, USA

    Jeffrey Moore

  11. DLR-Institut für Planetenerkundung, Rudower Chaussee 5, 12489, Berlin, Germany

    Gerhard Neukum

  12. Department of Earth and Space Sciences, University of California, Los Angeles, 90095, California, USA

    Gerald Schubert

Authors
  1. Michael H. Carr
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  2. Michael J. S. Belton
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  3. Clark R. Chapman
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  4. Merton E. Davies
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  5. Paul Geissler
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  6. Richard Greenberg
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  7. Alfred S. McEwen
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  8. Bruce R. Tufts
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  9. Ronald Greeley
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  10. Robert Sullivan
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  11. James W. Head
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  12. Robert T. Pappalardo
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  13. Kenneth P. Klaasen
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  14. Torrence V. Johnson
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  15. James Kaufman
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  16. David Senske
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  17. Jeffrey Moore
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  18. Gerhard Neukum
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  19. Gerald Schubert
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  20. Joseph A. Burns
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  21. Peter Thomas
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  22. Joseph Veverka
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Corresponding author

Correspondence to Michael H. Carr.

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Carr, M., Belton, M., Chapman, C. et al. Evidence for a subsurface ocean on Europa. Nature 391, 363–365 (1998). https://doi.org/10.1038/34857

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  • DOI: https://doi.org/10.1038/34857

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