Tiny grains from the interior ocean of Enceladus


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Using Cassini scientists have detected tiny grains of rock orbiting Saturn that they think were formed on the floor of the interior ocean of Enceladus and then spewed out its vents into space.

They believe that these silicon-rich grains originate on the seafloor of Enceladus, where hydrothermal processes are at work. On the seafloor, hot water at a temperature of at least 90 degrees Celsius dissolves minerals from the moon’s rocky interior. The origin of this energy is not well understood, but likely includes a combination of tidal heating as Enceladus orbits Saturn, radioactive decay in the core and chemical reactions.

As the hot water travels upward, it comes into contact with cooler water, causing the minerals to condense out and form nano-grains of ‘silica’ floating in the water. To avoid growing too large, these silica grains must spend a few months to several years at most rising from the seafloor to the surface of the ocean, before being incorporated into larger ice grains in the vents that connect the ocean to the surface of Enceladus. After being ejected into space via the moon’s geysers, the ice grains erode, liberating the tiny rocky inclusions subsequently detected by Cassini.

Additional data suggest that the interior of Enceladus is very porous, which means that interior ocean might not be one large bubble but a complex liquid-filled cave.

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2 comments

  • David M. Cook

    The only way to properly examine these worlds is for humans to actually go there and perform research from the surface. Robotic missions have their place, but for real scientists to obtain real data there’s no substitute for boots-on-the-ground programs. I wish more planetary scientists would push for manned missions to allow for a much more complete examination of our solar system.

  • Max

    “Cassini scientists also reported on the abundance of methane spewing into the atmosphere of Enceladus.”
    I believe this is what the oceans is made of, not water. Methane from the sun (main component of the solar wind) is plentiful and will freeze to all cold surfaces in layers over billions of years will become very thick. Methane will boil at -258F at one atmosphere. (turns into a liquid at near 300° below zero at one atmosphere) not much heat required to cause outgassing. Once the methane is exposed to the cold of space, it will refreeze to the surface or Sublimes from near orbit. The pressure of the ice on top pushing down, combined with tidal forces will provide enough heat to do the job.
    As for the dust grains spewing into space, the measurement of 2 to 8 nanometers seems excessively small. Bacteria is 5 to 20 micrometers in size. Viruses are 30 to 50 nm. small. 20 large Atoms lined up is about 2 nanometers long. It is very difficult to measure the dust grains that are smaller than the wavelength of visible light.
    On the other hand, the dust grains in heavy concentrations will block light just like looking at city smog through miles of atmosphere makes it visible.
    I too think we need to send someone there to study it directly. I barely remember the lunar landing as a child, I truly thought man would be living on the moon by now…

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