On Thursday NASA will announce evidence that hydrothermal activity on the floor of an ice-covered ocean on Saturn's moon Enceladus is most likely creating methane from carbon dioxide. The process is indicative of possible habitable zones within the ocean of Enceladus.
But before we go any further, "habitable" does not mean "inhabited".
NASA bases this determination on the amount of hydrogen in plumes emanating from the moon's south pole. The large amount of hydrogen is strongly suggestive of a constant hydrothermal process wherein the ocean under the surface of Enceladus is interacting with rock and organic compounds. The amount of hydrogen present is in disequilibrium i.e. if there was not a process that was constantly generating hydrogen the observed hydrogen levels would likely be lower than what is seen. Something is pumping it out.
Saturn's moon Enceladus is known to have an ocean beneath its icy surface. This small moon constantly sprays its ocean's contents into space from vents at its south pole from a region referred to as the "tiger stripes" due to the appearance of the location. The Cassini spacecraft has actually flown through these plumes many times and sampled their composition. Based on these plume studies it has been previously determined that the ocean of Enceladus interacts with a rocky bottom.
