Europa as the Abode of Life
Posted on | October 19, 2009
We can practically smell the life from here:
The global ocean on Jupiter’s moon Europa contains about twice the liquid water of all the Earth’s oceans combined. New research suggests that there may be plenty of oxygen available in that ocean to support life, a hundred times more oxygen than previously estimated.
The chances for life there have been uncertain, because Europa’s ocean lies beneath several miles of ice, which separates it from the production of oxygen at the surface by energetic charged particles (similar to cosmic rays). Without oxygen, life could conceivably exist at hot springs in the ocean floor using exotic metabolic chemistries, based on sulfur or the production of methane. However, it is not certain whether the ocean floor actually would provide the conditions for such life.
Therefore a key question has been whether enough oxygen reaches the ocean to support the oxygen-based metabolic process that is most familiar to us. An answer comes from considering the young age of Europa’s surface. Its geology and the paucity of impact craters suggests that the top of the ice is continually reformed such that the current surface is only about 50 million years old, roughly 1% of the age of the solar system.
Richard Greenberg of the University of Arizona has considered three generic resurfacing processes: gradually laying fresh material on the surface; opening cracks which fill with fresh ice from below; and disrupting patches of surface in place and replacing them with fresh material. Using estimates for the production of oxidizers at the surface, he finds that the delivery rate into the ocean is so fast that the oxygen concentration could exceed that of the Earth’s oceans in only a few million years. Greenberg presented his findings at the 41st meeting of the American Astronomical Society’s Division for Planetary Sciences now under way in Fajardo, Puerto Rico.
