Cassini discovered a salty ocean under the surface of Enceladus, Saturn's moon PDF Print E-mail
Thursday, 23 June 2011 11:46


A team of scientists from the University of Heidelberg, jointly with scientists from the University of Colorado, based on analysis of data, received from NASA interplanetary Cassini-Huygens mission, have identified a large probability of finding an ocean of salt water under the surface of Enceladus, Saturn's Moon.

Cassini-Huygens mission is a cooperative project of NASA with the space agencies of Europe to study Saturn, which was launched in 1997 and reached Saturn's orbit on July 1, 2004. Cassini-Huygens mission is composed of a spacecraft Cassini, carrying a lander Huygens. In 2008, the Cassini-Huygens project was renamed the Cassini Equinox. Although initially it was assumed, that the mission will end in 2008, but the timing twice been extended, the last time it was extended to 2017.

During the mission, the Cassini thrice came closer to Enceladus, and as a result, it was able to take pictures of unusual geysers are erupting on this Moon of Saturn in the long fractures on its surface, which later were called "tiger stripes". In early November 2009, the Cassini came within just 100 km from Enceladus, being able to analyze the composition of a substance that is released from its geysers. This was possible due to the fact, that Enceladus has a relatively small size, its diameter is only 450 kilometers, so due to the low gravity, the particles from the geysers can fly quite far from this Moon of Saturn.

Numerous data, obtained in the analysis of emissions from the geysers on this Moon of Saturn, indicate, that salt water in the liquid phase is located in large quantities under the surface of Enceladus, as the geysers of Enceladus consist from 91% of water, which also found presence of salt. As noted by Frank Rosterberg, the salt concentration rises toward the surface of Enceladus, which makes it very possible hypothesis about the presence of water in liquid form under the surface of Enceladus.

William Gershel discovered Enceladus in 1789. But because of the small size of Enceladus, the first data about Enceladus had been received only in the early 1980s, when the station "Voyager 1" has found that Enceladus orbits within the densest part of Saturn's rings are scattered - the E ring and communicates with these substances, and the station "Voyager-2" found that on the surface of Enceladus are the most diverse landscapes with signs of tectonic activity. After that, already, since 2005, the Cassini several times passed near the Enceladus, revealing active geysers on its surface, as well as the existence of geologic activity.

It should be noted, that the presence of geological activity on such a small Moons was not unexpected, since the Moons in the satellite systems of Jupiter and Saturn are often caught by the orbital resonances of these large planets, which lead to orbital eccentricity, and can cause intermittent heating the interiors of these satellites. Therefore, Enceladus is one of three celestial bodies beyond the terrestrial planets (with Jupiter's Moon Io and Neptune's satellite Triton) with active tectonic activity and eruptions.

In particular, the analysis of the eruptions from Enceladus were found to have a 91% water, 4% - of nitrogen, 3.2% of carbon dioxide and 1.7% - from methane. This unique combination of chemicals makes Enceladus a prime candidate for an astrobiological research beyond the Earth, as the relentless tectonic activity on Enceladus is almost one hundred percent indicates the existence of water in liquid form just under its surface.

Scientists around the world immediately turned to the fact, that the existence of such a combination of chemical composition of the interior of Enceladus, and tectonic activity on its surface. Interesting hypothesis previously contained in two research articles, which were published in the journal "Icarus". One article called: “ Enceladus' plume: Compositional evidence for a hot interior”, another article called: “ Enceladus's South Polar Sea”. According to the basic concept in these articles, if the nitrogen in Enceladus was the result of chemical decomposition of aqueous ammonia, then it requires a high temperature, so it is possible to create a supportive environment (includes water in the liquid state, high temperature, nitrogen and methane) which is necessary for the synthesis of more complex organic compounds and even amino acids, which are the initial compounds necessary for the emergence of biological life.

Thus, in theory, according to scientists,- on Enceladus were established in almost all the initial conditions for the emergence of biological life. However, the spectrometers of Cassini could not register the presence of amino acids in the emissions of Enceladus geysers, since its sensitivity is not designed for analysis of such compounds.

But scientists hope, that future expeditions to the Enceladus would lead to the greatest sensation- the detection of biological life beyond Earth.




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