Scientists have learned the conditions on the bottom of the icy ocean of Enceladus, the satellite of Saturn

    Enceladus is the sixth largest satellite of Saturn, known for the active activity of geysers. Thanks to the Cassini spacecraft, many unique discoveries were made, mostly about the nature of the discovered ice geysers, which emit water vapor and dust particles hundreds of kilometers high. The conclusion was drawn about the leading role of Enceladus in the formation of one of the rings of Saturn. Last year, research results on the subsurface ocean existing on Enceladus were published. And finally, this week two papers were published indicating the first clear signs of hydrothermal activity at the bottom of the subsurface ocean.
    The diagram depicts possible hydrothermal activity on and under the bottom of the subsurface ocean.

    The first work concerns microscopic rock particles discovered by Cassini in the Saturn system.
    A large study lasting 4 years analyzed the data from the spacecraft, the results of computer simulations and laboratory experiments, and led the researchers to conclude that tiny particles were most likely formed when hot water containing dissolved minerals from Enceladus rock formations entered the ocean, and interacts with cooler water. The temperatures required for the interaction forming tiny rock particles are at least 90 degrees Celsius.

    The Cassini-based cosmic dust analyzer recorded silica particles, the largest of which were 6–9 nanometers in size. A necessary condition for the formation of such particles is a large temperature drop of slightly alkaline and salt water, oversaturated with silicon dioxide. A team of researchers from the University of Tokyo suggests that the necessary conditions exist at the bottom of the subsurface ocean when hot water comes out of the rock and interacts with the cold near-bottom ocean water.
    The small size of the particles suggests that they relatively quickly reach the surface of the ocean and outer space (distance of 50 kilometers) - within a few months or years, otherwise their size would be larger.
    The authors of the work note that the gravitational measurements of Cassini suggest that the stone core of Enceladus is relatively porous, which allows water from the ocean to seep inside. Which gives a huge surface area where water and rock can interact.
    Scientists consider two hypotheses of the appearance of methane in geysers.

    The second study suggests hydrothermal activity as one of the two possible sources of methane in geysers that erupt from the southern polar region of Enceladus. This conclusion was drawn from the results of extensive modeling by French and American scientists to address the issue of the unusual abundance of methane in geyser emissions. A study by a group of scientists clathrates in the ocean, Enceladus led them to the idea that methane is actively produced by hydrothermal processes.

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