We’ve suspected for some time that there were geysers on Saturn’s moon of Enceladus and that there may lie underneath them an underground ocean partly comprised of liquid water. This month, further analysis of data transmitted by the Cassini probe has revealed that there are at least 101 visible geysers. And that’s not all:
The coincidence of individual jets with very small (~10 m) hot spots detected in high resolution Cassini VIMS data strongly suggests that the heat accompanying the geysers is not produced by shearing in the upper brittle layer but rather is transported, in the form of latent heat, from a sub-ice-shell sea of liquid water [emphasis mine], with vapor condensing on the near-surface walls of the fractures.
The existence of an underwater reservoir, the heat produced by geyser activity, and the general presence of liquid water on the planet strongly suggest that Enceladus may, in fact, be able to support some form of life.
What’s more, the geysers themselves may provide us with an opportunity to non-invasively confirm the presence of life on Enceladus. As I noted earlier this year in my writeup on Ganymede, actually digging into the underground oceans of planets and moons may be destructive to any life we find. But it would be much simpler and much less dangerous to simply pass a probe through one or more of these geysers, gather samples, and test the vapor for evidence of microbial life. If it’s present, we will know that we are dealing with an extraterrestrial ecosystem below the surface—and that if we plan to explore it any further, we will need to proceed with caution.