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article imageAlien life on Saturn's moon, Enceladus, much more likely

By Stephen Morgan     Mar 12, 2015 in Science
New data from NASA's Cassini mission to explore Saturn and its moons has scientists excited. The agency's space probe has just found conditions on the planet's moon, Enceladus, which makes the discovery of alien life there far more probable.
A lot of attention has recently concentrated on the chances of finding life on Saturn's other moon, Titan or the dwarf planet Ceres. While that remains a strong possibility, new information gathered on another of Saturn's moons, Enceladus, has put it back in the spotlight as a candidate for finding extraterrestrial life.
While the freezing surface conditions on Enceladus make life as we know it unsustainable, there is a strong possibility that life forms do exist in the moon's underground oceans. It now seems that the ecosystem there is extremely similar to those in deep oceans on Earth. This has been a point of speculation for some time and now it seems to have been confirmed.
According to
Gravity measurements have shown that there is at least a local and possibly a global ocean under Enceladus' icy crust, and some of the emitted grains are rich in sodium salt, which indicates the presence of a salty ocean.
Former analyses made by the Cassini spacecraft have already pointed towards the possibility of life, but what is new is that scientists have found proof of oceanic hydrothermal activity similar to our own.
"Hydrothermal activity occurs when seawater infiltrates and reacts with a rocky crust and emerges as a heated, mineral-laden solution, a natural occurrence in Earth's oceans," says the Mail Online.
This is exciting because, here on Earth, we have already discovered completely unexpected and strange life forms deep in our oceans, where it was thought that the temperatures and the lack of sunlight made life impossible.
Instead, researchers have found the most resilient examples of creatures and microbial life to be alive and kicking, especially around inhospitable underwater volcanoes and hydrothermal vents.
The University of Washington educational and research site, Lost City, explores deep sea phenomenon – "Lost City" is the name of a hydrothermal field in the Atlantic. It explained:
Deep-sea hydrothermal vents are characterized by large chimneys venting extremely high temperature fluids (350-400°C = 572°F) and “black smoke”, and unusual types of organisms including gigantic tube worms, clams, and crabs. These systems also harbor micro-organisms that use energy sources derived from volcanoes in the seafloor, and include an organism which grows at the highest temperature known for life, 113°C (235°F).
We now know that Enceladus contains "a liquid ocean of salty water that exists in contact with a rocky, silicate seabed from which the oceans can absorb complex minerals and elements," says, and these conditions could provide the "soup" from which life could develop.
Cassini identified silicate produced close to hydrothermal vents in temperatures over 90°C, which is similar to conditions around the ridges of volcanic vents on Earth. Silica particles coming from Enceladus were found in Saturn's rings. They are rare in the solar system, but can be found easily on Earth. It was presence of nanosilica grains which led the researchers towards the likelihood of hydrothermal activity.
Cassini already observed plumes of water coming from geysers on Enceladus back in 2005, but now linking this to proof of hydrothermal activity means geological activities are taking place similar to Earth.
Engadget explains the importance of such information:
...these geysers are caused by hydrothermal vents or fissures that heat the water at the bottom of the 6-mile-deep ocean beneath the Saturn's moon ice crust. Why is that important? Well, if the vents truly exist, the waters that surround them will contain chemicals and minerals necessary for life. Plus, the conditions around those vents will be similar to the environment surrounding Atlantic Ocean's hydrothermal field -- the place where life on Earth might have begun.
geysers bursting through an icy crust  Enceladus is a tiny moon with a big personality. Credit: Hsia...
geysers bursting through an icy crust, Enceladus is a tiny moon with a big personality. Credit: Hsiang-Wen Hsu et al/Nature Enceladus - geysers bursting through an icy crust, Enceladus
Hsiang-Wen Hsu et al/Nature
Commenting on the findings, NASA says:
"Small, icy Enceladus is of great scientific interest because it is surprisingly active. Cassini discovered an icy plume shooting from this moon, and subsequent observations have revealed the spray contains complex organic chemicals. Tidal heating is keeping Enceladus warm, and hotspots associated with the fountains have been pinpointed. With heat, organic chemicals and, potentially liquid water, Enceladus could be a place where primitive life forms might evolve."
The LA Times quotes planetary scientist Hsiang-Wen Hsu from the University of Colorado, Boulder, who commented, "It’s kind of obvious, the connection between hydrothermal interactions and finding life. These hydrothermal activities will provide the basic activities to sustain life: the water, the energy source and of course the nutrients that water can leach from the rocks.”
John Grunsfeld, astronaut and associate administrator of NASA's Science Mission Directorate in Washington, said, "These findings add to the possibility that Enceladus, which contains a subsurface ocean and displays remarkable geologic activity, could contain environments suitable for living organisms."
It is fascinating to speculate on what might be alive in these subterranean oceans.
Describing the discovery of life in similar conditions on Earth, the website of the National Oceanic & Atmospheric Administration says:
"Until then, scientists believed all life on Earth was part of a photosynthetic food chain, drawing energy from the sun. The discovery revealed hidden “alien” life forms living on our own planet in the dark ocean depths and relying only on chemicals to survive. Tubeworms and huge clams are among the distinctive inhabitants of Pacific Ocean vent sites, while eyeless shrimp have been found at vents in the Atlantic Ocean."
The study was carried out by researchers from the University of Colorado at Boulder and was published this week in the journal Nature.
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