- Enceladus is a small moon of Saturn that, from its large-scale external appearance gives the superficial impression of being a cold, generally barren and astrobiologically unpromising place. Yet evidence strongly suggests fascinating features sharply at odds with this impression.
- Strong evidence indicates that, around the south polar region, under a thick layer of water ice, Enceladus harbors a large, salty subsurface liquid water ocean; this ocean may be heated and kept liquid largely by tidal heating related to the force of gravity from Saturn. Furthermore, the ocean is thought to contact Titan’s rocky core, which could potentially provide nutrients and lead to chemical reactions favorable to life.
- Tidal heating may also provide an explanation for another intriguing feature discovered around the south polar region: cryovolcanism. Imaging performed by the Cassini-Huygens spacecraft during a 2005 fly-by of Enceladus confirms active surface cryovolcanos (“ice volcanos”) spewing geyser-like jets of massive amounts of icy particles and water vapor out at enormous speeds from its interior, beyond its surface, and into space. Furthermore, traces of simple hydrocarbons have been detected the cryovolcano plumes, thought to have originated in Titan’s subsurface ocean. Still further, it is thought that hydrothermal vent activity at the interface of the ocean with Enceladus’ rocky core may well be powering these cryovolcanos. This, in turn, leads to speculation about possible life around such hydrothermal vents, much like life thrives around hydrothermal vents in the oceans of Earth, even in the absence of oxygen and sunlight.
- It is thought that the cryovolcanoes around Encedadus’ southern polar area may be spewing water originating from the subsurface ocean, pressured through fissures in Enceladus’ thick, icy crust.
- The strong evidence for features including a liquid water subsurface ocean in contact with a rocky core, the presence of organic compounds, cryovolcanism, and possible hydrothermal vent activity all combine to make the small, barren-looking Enceladus a none the less intriguing candidate for possibly harboring life.
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