Wikipedia https://en.wikipedia.org/wiki/Europa_(moon)#Subsurface_oceansays that "Scientists' consensus is that a layer of liquid water exists beneath Europa's surface, and that heat from tidal flexing allows the subsurface ocean to remain liquid."There have been speculations that Europa might contain life. For example, "Europa is the most likely place in our solar system beyond Earth to possess .... life," said Robert Pappalardo, a planetary scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California. http://phys.org/news/2013-02-jupiter-europa-moon-likeliest-life.html I am curious to find out what the knowledgeable participants at PF speculate the implications are if, someday, life is found on Europa, or Europa is found to not have life. In particular how will such a finding affect the likelihood that life exists on some exoplanet in the Milky Way. That is, to what extent would finding (not finding) life on Europa affect the probability that life exists (does not exist) elsewhere in the Milky Way. Another area of interesting speculation would be: If life is not found on Europa, what particular difference(s) between Earth and Europa might explain this. For one example, it might be that liquid water temperatures on Earth range from < 0 C (due to salts in the ocean) to 100 C (due to sub-ocean mantle plumes), while the range of water temperatures on Europa are likely to be more limited.