Our solar system is a living proof that life could evolve way beyond the famous habitable region (a.k.a. the Goldilocks zone), which keeps water in liquid form, a must in any current theory about life’s existence in the universe. Icy planets or moons, as cold as they seem at surface, could benefit from a heat source inside them. Thus, deep under miles and miles of frozen water, oceans quite similar to our arctic region could hide life, at least in the form of microorganisms. Accordingly, two moons are currently considered to be the best candidates for harboring life outside Earth in our planetary backyard: Jupiter’s Europa and Saturn’s Enceladus.
Last month the NASA’s Cassini spacecraft celebrated 10 years of exploration of Saturn system, a great deal of time being spent on monitoring Enceladus. In 2005, the scientific community witnessed for the first time a promising phenomenon on this small icy moon, the existence of geysers erupting at its frozen surface. During the last 7 years, Cassini’s cameras monitored a region located at the south pole of Enceladus, very well known for its geyser related geologic activity. The result of the data gathering was a map showing 101 individual geysers, which proved to add invaluable information regarding the much debated origin of this geological phenomenon. Previously, two theories tried to explain the mechanisms behind the heat source needed to power the geysers. One stated that frictional heat between the opposing walls in the frozen crust’s fractures moved by Saturn’s gravity generates the high temperatures that turns ice into liquid and vapor. Another hypothesis considered that the movement of the fractures simply allow the hot water from a liquid ocean/reservoir to reach the moon’s surface.
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By analyzing the location of geysers by the method of triangulation and combining these data with previous information based on Cassini’s heat seeking instruments in 2010, the Cassini imaging team working at the Space Science Institute in Bolder, Colorado, solved the mystery behind the origin of Enceladus’ geysers. The match between the location of the geysers and the previously identified hot spots, which are only several dozen feet across, “too small to be induced by frictional heating”, led to the conclusion that geysers must be induced by a well bellow surface energy source. Thus, these data confirmed that the sea currently known to exist under the frozen surface is the source of the southern geyser basin’s activity.