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Mars Earth

Mars May Hide Oceans of Water Beneath Its Crust, Study Finds (space.com) 53

Oceans' worth of water may remain buried in the crust of Mars, and not lost to space as previously long thought, a new study finds. Space.com reports: Data from NASA's MAVEN (Mars Atmosphere and Volatile EvolutioN) mission and the European Space Agency's Mars Express orbiter revealed that at the rate water disappears from the Red Planet's atmosphere, Mars would have lost a global ocean of water only about 10 to 82 feet (3 to 25 m) deep over the course of 4.5 billion years. Now scientists find that much of the water Mars once had may remain hidden in the crust of the Red Planet, locked away in the crystal structures of rocks beneath the Martian surface. They detailed their findings online March 16 in the journal Science and at the Lunar Planetary Science Conference.

In the new study, the scientists found chemical reactions may have led between 30% to 99% of the water that Mars initially had to get locked into minerals and buried in the planet's crust. Any remaining water was then lost to space, explaining the hydrogen-to-deuterium ratios seen on Mars. All in all, the researchers suggested Mars lost 40% to 95% of its water during its Noachian period about 4.1 billion to 3.7 billion years ago. Their model suggested the amount of water on the Red Planet reached its current levels by about 3 billion years ago.

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Mars May Hide Oceans of Water Beneath Its Crust, Study Finds

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  • by ytene ( 4376651 ) on Wednesday March 17, 2021 @05:33AM (#61167518)
    I'm about to make lots of assumptions... so please forgive that.

    If we assume that Mars is approximately the same age as the Earth (Wikipedia quotes 4.543 billion years) and that the water that is now or was once on Mars was placed there during the formation of Mars as a planet (qualification, it may not have been located with Mars as chemical water; there may have been processes over time which converted other compounds to water), then we can start to see some interesting patterns as we look at our solar system.

    Our Earth, with a gravity of "1g", has sufficient gravity to maintain an atmospheric envelope, which, in turn, helps to prevent liquid water from boiling off in to space and being lost.

    Our Moon, with a gravity of one sixth of "1g", has insufficient gravity to maintain an atmosphere and any water it may contain, like Mars, is likely "locked up" in rock structures.

    Mars, with a gravity of very approximately one third of "1g" has sufficient gravity to maintain a very thin atmosphere, but has also lost much (most?) of the water it may have initially acquired at formation. Obviously we don't know how much water that was relative to Earth.

    But in here there is a glimmering of a pattern: the idea that in order to maintain a hydrosphere - which we recognise as being necessary for life as we know it - then we need a "minimum planetary mass". Anything less than this minimal mass would be unable to retain an atmosphere and through this would also lose liquid water. (Yes, some may remain as ice in polar regions, but that would not support life).

    So do this give us an additional data point in our search for life? [ There's at least one caveat here - likely several - which is that the proximity of a planet to her star and the size/thermal output/radiation of that star would also be a major influence on the formation of liquid water and life. But it seems as though the preservation of liquid water has the dependency on an atmosphere [for insulation and partial pressure purposes] and that, in turn, might dictate planetary mass.

    I'm not sure what that might do to "upper limit" of planetary mass, but we might be able to say that planets below a certain mass could not host water long enough to permit the development of life.
    • Interesting idea. What's your take on an oceanic moon like Europa or an icy moon like Enceladus?

      • The reason for water ice on themis that it's colder because they're further from the Sun even though they're small bodies.
      • by ytene ( 4376651 )
        Joe, good challenge. I think tonique beat me to the answer... As I said at the opening of my earlier post, I was making a lot of assumptions. One of these is that there is of course a critical factor in terms of the distance of a planet from it's star and thus the mean temperatures [relative to the melting point and boiling point of water].

        Your example of Europa is a fantastic challenge to my theory, but it might help illustrate it more clearly. If Europa has liquid water beneath sufficiently thick froze
        • by rtb61 ( 674572 )

          I like Mars as a moon, that got a quick coat of the planet that it orbited, when that planet got taken out big time, enough to reverse it's rotation and of course that energy would hugely change it's orbit, can not have one without the other. That red surface on top of the gray surface rusty mud and rubble from the world it once orbited. That top surface can not be without water, oxidised as it crashed to the surface. Millions of years ago and the debris from that impact orbit around every 3,000 odd years t

          • by ytene ( 4376651 )
            The orbit of Mars has an eccentricity of 0.0934 [wikipedia.org] - in other words it is remarkably "regular" in terms of the way that it moves around our star.

            What I believe this means is that it is somewhere between "somewhat" and "highly" unlikely that Mars was formerly the moon of a long-lost planet. Were that the case, then the orbit of Mars would be significantly more eccentric than we see from observation.

            Obviously there are theories about our solar system, at some point in the distant past, having another "gas
      • One thing Europa has going for it is a lot of (in theory at least) tidal heating from Jupiter and the other Galilean moons nearby.
    • by Laxator2 ( 973549 ) on Wednesday March 17, 2021 @06:55AM (#61167628)

      Another factor to take into account is the magnetic field. The solar wind can erode a planet's atmoshpere in addition to the individual atoms escaping into space due to the planet's weak gravity.
      In fact, Venus is constantly losing its atmosphere to the solar wind, and since hydrogen is the lighest gas, it is the element that is most easily lost.

      https://www.britannica.com/pla... [britannica.com]

      Since water vapor in the atmosphere is broken down into hydrogen and oxygen and then the hydrogen is lost, the planet is in fact losing water. Earth has a strong magnetic filed, Mars and Venus have close to none.

      • by ytene ( 4376651 )
        Right... but that also becomes a factor of distance-from-the-star... If you take a 1-metre square of the upper atmosphere of Venus [and for the sake of exploring the point, let's agree that we'll determine "upper atmosphere" by measuring gaseous pressure to be consistent] and then count the number of solar wind particles detected per unit time... then repeat the experiment in Earth's atmosphere... you'd find a very significant difference.

        This is because of basic geometry... as the solar wind radiates out
      • by Tablizer ( 95088 )

        Would Venus have a stronger magnetic field if it rotated faster, so that tides can stir the magma? Part of the reason it rotates slow is because it's close to the sun, but that's probably not the only reason.

    • Maybe not just mass. But geothermal activity. It's Earth' volcanos that keep our water on the surface.
      • by ytene ( 4376651 )
        OK - the place I think you're helping us reach here is that there are multiple "ingredients" in the "recipe" needed for there to be liquid water on the surface of a world for sufficient time, perhaps, to allow "life as we know it" to emerge.

        Just from the contributions in this discussion thread, we've come up with:-

        - Gravity/Planetary mass
        - Geothermal Activity
        - A Magnetic Field
        - There will doubtless be others

        Obviously those are just some of the likely ingredients... we don't as yet know the relati
      • This is where I was thinking. Mars at one point had active volcanoes. This tells me at one point it had tectonic activity, which has sense ground to a halt. One Earth tectonic activity has lead to vast amounts of water being locked up inside the planet. I wonder if the same condition exists on Mars.

        • by PPH ( 736903 )

          On Earth tectonic activity has lead to vast amounts of water being locked up inside the planet.

          Not so much locked up as driven back to the surface. Turn down the Earth's internal heat source and I suspect that our oceans will sink into the cracks in the rocks.

    • by Rhipf ( 525263 )

      You may need to also factor in the magnetosphere in retaining liquid water as well.

      http://astrobiology.com/2019/0... [astrobiology.com]
      https://www.space.com/11187-ea... [space.com]

      • by ytene ( 4376651 )
        Indeed. PPH made the same observation, just up the thread a bit. Completely agree with you both.
        • by Rhipf ( 525263 )

          Ya, saw that. Guess I need to read deeper into threads before posting relies. 8^)

    • Now riddle us this: how does Titan, smaller than Mars, manage to hold onto an atmosphere half again as thick as Earth's?

      • by ytene ( 4376651 )
        The persistence of a dense atmosphere on Titan has been enigmatic as the atmospheres of the structurally similar satellites of Jupiter, Ganymede and Callisto, are negligible. Although the disparity is still poorly understood, data from recent missions have provided basic constraints on the evolution of Titan's atmosphere.

        Roughly speaking, at the distance of Saturn, solar insulation and solar wind flux are sufficiently low that elements and compounds that are volatile on the terrestrial planets tend to ac
      • Titan is most likely inside the magnetosphere of Saturn. Also it is relatively massive in comparison to Luna.

  • If you cannot be bothered to do your jobs, resign.

    • Welcome to Slashdot, where the editors could trivially be replaced by very small shell scripts with no drawbacks

  • The title is little misleading, however the further text explains the case better.

    Some studies indicate that certain minerals' (like e.g. olivine) water absorption is related to their temperature (the hotter the less water and vv).

    There is a video [youtube.com] about a hypothesis of an ocean Earth, as in the past our planet (the crust) had higher temperature, thus less water dissolved in the crust, thus more on the surface - possibly the same case is with Mars, so as it cooled the water was absorbed by some crust mineral

  • Ancient aliens theorists say "yes!"

  • The last thing we need is to give him more incentive for that suicide trip.
  • by Rhipf ( 525263 ) on Wednesday March 17, 2021 @10:44AM (#61168278)

    I remember seeing a documentary in the 1990 that showed that there was a massive amount of ice under the surface of Mars. Near the end of the documentary they even speculated that there could be a mechanism that could convert that ice into a breathable atmosphere so that people could live on Mars without needing special habitats built.

    Unfortunately I can't totally recall the name of the documentary.

    • by Tablizer ( 95088 )

      there could be a mechanism that could convert that ice into a breathable atmosphere so that people could live on Mars without needing special habitats

      If possible, it would probably be short-lived. Without a magnetic field, radiation would burn it away. And, you'd need a thick umbrella even with a full atmosphere, because a magnetic field is required to protect us sufficiently. Perhaps an atmosphere say roughly 3 times thicker than Earths may compensate, but that's a tall order.

      It may be easier to crash a b

    • by SETY ( 46845 )

      Come on...no funny mod?

      I think a former governor narrated that documentary.

  • Total Recall was right all along. Send Arnold on the first manned mission, he'll get it going.

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