Evidence for a subsurface ocean on Europa (original) (raw)

Nature volume 391, pages 363–365 (1998)Cite this article

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.

This is a preview of subscription content, access via your institution

Access options

Subscribe to this journal

Receive 51 print issues and online access

$199.00 per year

only $3.90 per issue

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Additional access options:

Similar content being viewed by others

References

  1. Kuiper, G. P. Planets and Satellites (Univ. Chicago Press, 1961).
    MATH Google Scholar
  2. Moroz, V. I. Infrared spectrophotometry of the Moon and the Galiliean satellites of Jupiter. Sov. Astron. A. J. 9, 999–1006.
  3. Morrison, D. & Cruikshank, D. P. Physical properties of the natural satellites. Space Sci. Rev. 15, 641–739 (1974).
    Article ADS CAS Google Scholar
  4. Anderson, J. D., Lau, E. L., Sjogren, W. L., Schubert, G. & Moore, W. B. Europa's differentiated internal structure: Inferences from two Galileo encounters. Science 276, 1236–1239 (1997).
    Article ADS CAS Google Scholar
  5. Smith, B. A.et al. The Galilean satellites and Jupiter: Voyager 2 imaging science results. Science 206, 927–950 (1979).
    Article ADS CAS Google Scholar
  6. Cassen, P., Reynolds, R. T. & Peale, S. J. Is there liquid water on Europa? Geophys. Res. Lett. 6, 731–734 (1979).
    Article ADS Google Scholar
  7. Cassen, P., Reynolds, R. T. & Peale, S. J. Tidal dissipation on Europa: A correction. Geophys. Res. Lett. 7, 987–989 (1980).
    Article ADS Google Scholar
  8. Squyres, S. W., Reynolds, R. T., Cassen, P. & Peale, S. J. Liquid water and active resurfacing on Europa. Nature 301, 225–226 (1983).
    Article ADS CAS Google Scholar
  9. Ross, M. & Schubert, G. Tidal heating in an internal ocean model of Europa. Nature 325, 13–134 (1986).
    Google Scholar
  10. Ojakangas, G. W. & Stevenson, D. J. Thermal state of an ice shell on Europa. Icarus 81, 220–241 (1989).
    Article ADS CAS Google Scholar
  11. Greenberg, R. & Wiedenschillling, S. J. How fast do Galilean satellites spin? Icarus 58, 186–196 (1984).
    Article ADS Google Scholar
  12. Helfenstein, P. & Parmentier, E. M. Patterns of fractures and tidal stresses due to non-synchronous rotation: Implications for Europa. Icarus 612, 175–184 (1985).
    Article ADS Google Scholar
  13. McEwen, A. S. Tidal reorientation and the fracturing of Jupiter's moon Europa. Nature 321, 49–51 (1986).
    Article ADS Google Scholar
  14. Pappalardo, R. T., Head, J. W., Greeley, R. & the Galileo Imaging Team. AEuropa ocean? The (circumstantial) geological evidence. in Proc. Europa Ocean Conf. 59–60 (1996).
  15. Lucchitta, B. L. & Soderblom, L. A. in Satellites of Jupiter (ed. Morrison, D.) 521–555 (Univ. Arizona Press, Tucson, 1982).
    Google Scholar
  16. Pappalardo, R. T. & Coon, M. D. Asea analog for the surface of Europa. Lunar Planet. Sci. Conf. XXVII, 997–998 (1996).
    ADS Google Scholar
  17. Greeley, R.et al. Europa: Initial Galileo geological observations.(submitted).
  18. Pappalardo, R. T.et al. Geological evidence for solid-state convection in Europa's ice shell. Nature 391, 365–368 (1998).
    Article ADS CAS Google Scholar
  19. Schenk, P. M. & McKinnon, W. B. Fault offsets and lateral crustal movement on Europa: Evidence for a mobile ice shell. Icarus 79, 75–100 (1989).
    Article ADS CAS Google Scholar
  20. Pappalardo, R. T. & Sullivan, R. J. Evidence for separation across a gray band on Europa. Icarus 123, 557–567 (1996).
    Article ADS Google Scholar
  21. Sullivan, R. & the Galileo Imaging Team. Galileo views of crustal disruption on Europa. Lunar Planet. Sci. Conf. XXVIII, 1395–1396 (1997).
    ADS Google Scholar
  22. Tufts, R. B., Greenberg, R., Sullivan, R., Pappalardo, R. & the Galileo Imaging Team. Lunar Planet Sci. Conf. XXVIII, 1455–1456 (1997).
    Google Scholar
  23. Shoemaker, E. M. The age of Europa's surface.in Proc. Europa Ocean Conf. 65–66 (1996).
  24. Chapman, C. R. & the Galileo Imaging Team. Populations of small craters on Europa, GanymedeandCallisto:InitialGalileoimagingresutls. Lunar Planet. Sci. Conf. XXVIII, 217–218 (1997).
    ADS Google Scholar

Download references

Author information

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

Corresponding author

Correspondence toMichael H. Carr.

Rights and permissions

About this article

Cite this article

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

Download citation

This article is cited by