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NASA Earth Science

Nearby Ocean Worlds Could Be Best Bet For Life Beyond Earth, Says NASA ( 59

NASA has new evidence that the most likely places to find life beyond Earth are Jupiter's moon Europa or Saturn's moon Enceladus. In terms of potential habitability, Enceladus particularly has almost all of the key ingredients for life as we know it, researchers said. From a report: New observations of these active ocean worlds in our solar system have been captured by two NASA missions and were presented in two separate studies in an announcement at NASA HQ in Washington today. Using a mass spectrometer, the Cassini spacecraft detected an abundance of hydrogen molecules in water plumes rising from the "tiger stripe" fractures in Enceladus' icy surface. Saturn's sixth-largest moon is an ice-encased world with an ocean beneath. The researchers believe that the hydrogen originated from a hydrothermal reaction between the moon's ocean and its rocky core. If that is the case, the crucial chemical methane could be forming in the ocean as well.
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Nearby Ocean Worlds Could Be Best Bet For Life Beyond Earth, Says NASA

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  • Vote Europa (Score:5, Informative)

    by Tablizer ( 95088 ) on Thursday April 13, 2017 @04:56PM (#54230813) Journal

    Europa should be better hunting grounds than Enceladus because Europa has been similar to how it is now for probably most of its life. Enceladus's condition may merely be a coincidence in time: nobody really knows yet what heats Enceladus; its heat may be periodic or temporary.

    But we know that tidal forces with Jupiter and its other big moons are what heats Europa. Its big neighboring moons have been around probably since the formation of the Jupiter system.

    Europa's heat matches tidal models, meaning it probably had lots of time to evolve and nurture life. Saturn has only one big moon, Titan, and it's rather far from Enceladus, and thus not a notable tidal force.

    Plus, Europa is much bigger than Enceladus, giving life more chances to form.

    • by wonkey_monkey ( 2592601 ) on Thursday April 13, 2017 @05:10PM (#54230901) Homepage

      Europa should be better hunting grounds than Enceladus

      Yeah, but we're not allowed to land there.

      • by c-A-d ( 77980 )

        Fortunately, all the other planets are available for our use.

        • All these worlds are yours except Europa. And Mimas between 5 and 6 on Wednesday afternoons. You can have Triton on alternate Sundays, but hands off Margaret [].

    • Re:Vote Europa (Score:5, Interesting)

      by spaceman375 ( 780812 ) on Thursday April 13, 2017 @05:34PM (#54231065)

      It's not the proximity of another moon that produces tidal forces. Just going around Saturn is enough to produce the stresses that induce heat. We can't match the heat output in our models yet because we don't have enough data on the composition of Enceladus or the size of it's ocean(s). We can't even characterize how much heat comes from nuclear decay in our own core; we're just guessing about other planets and moons. Some of Europa's heat comes from the high radiation and strong magnetic fields in the Jupiter system, so the accuracy of your claim that it's heat matches only tidal stresses is doubtful.

      • by Geoffrey.landis ( 926948 ) on Thursday April 13, 2017 @05:40PM (#54231119) Homepage

        It's not the proximity of another moon that produces tidal forces. Just going around Saturn is enough to produce the stresses that induce heat.

        Only if the orbit is eccentric. If there aren't other moons, viscoeleastic damping circularizes the orbit until the tidal heating disappears-- it's the other moons that perturb Europa's orbit to make it slightly eccentric, giving it the tidal forces that heat it.

        • by Anonymous Coward

          "Its resonance with Dione excites its orbital eccentricity, which is damped by tidal forces, tidally heating its interior, and possibly driving the geological activity."

          "However, for Enceladus to still be active, part of the core must have also melted, forming magma chambers that would flex under the strain of Saturn's tides. Tidal heating, such as from the resonance with Dione or from libration, would then have

      • Just going around Saturn is enough to produce the stresses that induce heat

        Because its orbit is not particularly eccentric, that's too small a force to account for most the heat under the current models.

        We have other moons and planets in the solar system to study heat and test our models on frictional tidal heating, internal nuclear decay, and mineral composition. Enceladus doesn't fit that data. Yes, it's possible there's something really different or odd about its composition, but nobody has identified s

    • I remember a long time ago reading that Europa had fallen out of favor as the best place to look because they thought the ocean was too salty (based on magnetic field?).

  • TFA is a CNN story? Here is a better source. []

    I love the idea of a mission to Europa or Enceladus. The best support for life existing there is right here on earth, on geothermal vents deep in the ocean. [] Life already exists in total darkness and feeds on hydrogen sulfide, under extreme pressure in water that's hotter than its boiling point on the surface.

    • In fact, it's theorized that those hydrothermal vents may be where life first originated on Earth. One could argue that they are thus the most habitable place on Earth.

      • Maybe. An argument I'd use against geothermal vents being the origin of life on earth is that the environment in those conditions is too static and thus doesn't have the same evolutionary pressures. Its why the deeper you go in the ocean, the more living fossils you find.

        I'm not a biochemist, but I would be interested to know if there was a particular quality of the deep sea hydrothermal vents that would have been more favorable for the formation of life in comparison to the rest of the young planet.

    • If you're going to one, I wonder how much more difficult it is to go to both at the same time? A vessel that splits as it approaches sending similar payloads to both moons.

  • Now that they know an ocean world is the best bet for finding life, they can limit their searches to those sorts of places - plus they can use an AI to do automated image matches against known pictures of Kevin Costner.

"You can have my Unix system when you pry it from my cold, dead fingers." -- Cal Keegan