The search for current geologic activity on Europa

Cynthia B. Phillips, Alfred S. McEwen, Gregory V. Hoppa, Sarah A. Fagents, Ronald Greeley, James E. Klemaszewski, Robert T. Pappalardo, Kenneth P. Klaasen, H. Herbert Breneman

Research output: Contribution to journalArticlepeer-review

50 Scopus citations


Observational evidence and theoretical arguments suggest that Jupiter's satellite Europa could be geologically active and possess an "ocean" of liquid water beneath its surface at the present time. We have searched for evidence of current geologic activity on Europa in the form of active plumes venting material above the surface and by comparison of Voyager and Galileo images to look for any changes on the surface. So far, we have observed no plumes and have detected no definitive changes. The lack of observed activity allows us to estimate a maximum steady state surface alteration rate of 1 km2 y-1 in the regions analyzed, assuming alterations will cover contiguous areas of at least 4 km2 over a period of 20 years. Assuming this as a constant, globally uniform resurfacing rate leads to a minimum average surface age of 30 million years. We also suggest that the lack of obvious circular albedo patterns on the surface due to plumes, coupled with the presence of bright-rayed craters such as Pwyll and the predicted sputtering erosion rate, implies that no large-scale plume activity has taken place over at least the last few thousand years. We thus conclude that if Europa's surface is currently active, any changes must be relatively small in spatial scale or episodic in nature rather than continuous. To detect potential small-scale surface changes, we need high-resolution comparisons between the Galileo data and future Europa Orbiter images.

Original languageEnglish (US)
Article number1999JE001139
Pages (from-to)22579-22597
Number of pages19
JournalJournal of Geophysical Research: Planets
Issue numberE9
StatePublished - Sep 25 2000

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Atmospheric Science
  • Astronomy and Astrophysics
  • Oceanography


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