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Thread: An Ocean, and Rivers on Mars?! Possible loss by photodissociation and impact of life on the surface.

  1. #1 An Ocean, and Rivers on Mars?! Possible loss by photodissociation and impact of life on the surface. 
    Forum Junior Double Helix's Avatar
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    It has been postulated that an ancient ocean once existed on Mars (1). Surface features which appear like shorelines represent what may have formed the boundaries which held a substantial volume of water. Certainly there are large river channels, and craters that appear to have classic deltas within them, both almost certainly formed by flowing water. The evidence strongly suggests that in the ancient past, Mars had substantial amounts of liquid water on the surface, and it may have persisted for extended periods of time.

    The Perseverance Rover recently landed on Mars inside of Jezero crater (2), near the planet's equator, which contains what appears to be two ancient river deltas (3). This area is a large ca. 50 km wide impact feature which is believed to have formed during the Late Heavy Bombardment (LHB), a period of intense impact events some might consider the final stage of the formation of the inner planets. The LHB is believed to have occurred ca. 4.1 to 3.8 bya.

    A study at Brown University (3) suggests that liquid water flowed into this crater on two separate occasions, and has what appears to be an outflow channel roughly opposite the inlet channels. The research suggests that the water dried out 3.5-3.8 bya.

    Data from orbiting spacecraft indicates that craters which formed later than 4 bya are not magnetized, but those which formed earlier are. This indicates that Mars likely lost its magnetic field around 4 bya, substantially before the liquid water events resulting in river channels and deltas flowing into, and out of, Jezero crater.

    If Mars lost its magnetic field 4 bya, it's surface would have then been subjected to intense radiation from the sun, and surface water should have been largely lost into space by photodissociation in the atmosphere. This suggests that the surface water which appeared in Jezero crater, significantly after the loss of the magnetic field, had not yet been lost, despite some 100s of millions of years of intense solar radiation. How could this have happened, and could all this radiation have minimized the appearance of life on the Martian surface after the collapse of its magnetic field? If so, life on Mars likely formed, if at all, prior to the loss of the field, or in subsurface aqueous regions. It would seem that Perseverance's chances of finding signs of ancient life in Jezero crater might depend on the Sun's impact on water in Jezero crater.

    Anyone have more knowledge of the surface water on Mars, and the solar radiation which has been hammering it for ca. 4 billion years and counting?


    1. https://en.wikipedia.org/wiki/Mars_ocean_hypothesis


    2. https://en.wikipedia.org/wiki/Perseverance_(rover)


    3. Ancient Martian Lake System Records Two Water-related Events - SpaceRef


    Last edited by Double Helix; March 16th, 2021 at 07:01 PM.
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    Wild guess: gravity is too low to hold evaporating water vapor.


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    Quote Originally Posted by mathman View Post
    Wild guess: gravity is too low to hold evaporating water vapor.
    That would suggest that Mars could not have held large volumes of water for over a billion years.

    Unless it had much more water at the start, and slowly lost it, and what we now know existed was a fraction of that "start" volume, which is certainly possible.


    BBC News reports today on some research that suggests a large part of it may be locked up in mineral hydrates:

    https://www.bbc.co.uk/news/science-environment-56400227


    Another distinct possibillity.
    Last edited by Double Helix; March 16th, 2021 at 06:32 PM.
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    As we can see Mars has water ( ice ) and according to some NASA`s research that was made in 2002 as far as I remember. So we might assume that such hypothesis that claims that there is more water under the crust
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    Quote Originally Posted by bearnard bale66 View Post
    As we can see Mars has water ( ice ) and according to some NASA`s research that was made in 2002 as far as I remember. So we might assume that such hypothesis that claims that there is more water under the crust
    Digging into the notion that there is evidence of significant amounts of water still existing beneath the surface of Mars, another search led to interesting observations from ESA's Mars Express orbiter (1).

    Initial ground-penetrating radar data did not provide sufficient resolution to be certain of the bright spots suggestive of water. But using more memory on the spacecraft to increase resolution of the radar signal does suggest that lakes of liquid water may exist below the southern ice-cap. The largest of these suspected lakes spans about 20 km , and is 1.5 km below the surface (2). Since the radar data is limited to near surface features, only shallow lakes can so far be indicated.

    Of course not everyone is buying into this data yet, but it looks pretty interesting. And those studying this data suggest that sub-surface liquid lakes could appear anywhere on Mars, and at greater depth. And there could be many of them!

    Other observations from Mars Express suggest that a frozen sea may exist below areas of Elysium Planitia. When you look at an image of this area from Mars Express (3), it does appear to have "plates" of frozen water that broke apart and are now covered in dust. These objects certainly do have "a similarity in appearance to ice blocks off Earth's Antarctica".

    Again, as usual, not everyone is buying into this either, but the referenced image is quite compelling. It seems that no one has a good alternate explanation for their appearance. It has been suggested however that these images represent "ghosts" of ice blocks which existed in the past, but have since sublimated away, leaving only the impression of current "ice blocks" (4). Hopefully future data will resolve this issue once and for all. The existence of large amounts of water on Mars would be very interesting, to be sure. Especially any which is near the surface and easily accessible.


    1. https://en.wikipedia.org/wiki/Mars_Express_Orbiter

    2. https://www.sciencemag.org/news/2018...r-ice-cap-mars

    3. https://apod.nasa.gov/apod/ap050228.html

    4. https://www.esa.int/Science_Explorat...f_a_frozen_sea
    Last edited by Double Helix; March 24th, 2021 at 07:58 PM.
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    Quote Originally Posted by mathman View Post
    Wild guess: gravity is too low to hold evaporating water vapor.
    Following up on the issue of sufficient gravity to hold water vapor, found a related article about why terraforming Mars is simply not likely due to the low temperatures existing today (1). It relates to our inability to increase surface temperatures to a level where humans could survive without advanced technology.

    These scientists suggest the only practical way of terraforming Mars is to increase the temperature at the surface by releasing large amounts of CO2 locked up in ice. This would raise temperatures to allow liquid water to exist on the surface, and perhaps provide a water cycle like that on earth. The article, quoting scientists from NASA, gives no indications about a problem with low gravity and escape of water. The biggest problem is keeping the temperature high enough, and of course producing O2 for respiration.

    And various surface rovers have captured images of high altitude water and CO2 clouds (2,3). If gravity was not sufficient to prevent escape of water, these clouds would not likely exist, nor would there be much surface water-ice on Mars as it would have been lost to space over the eons as a result of insufficient gravity.

    1. https://www.space.com/41318-we-cant-terraform-mars.html


    2. https://apod.nasa.gov/apod/ap210325.html


    3. https://apod.nasa.gov/apod/ap061017.html

    Last edited by Double Helix; March 26th, 2021 at 04:20 PM.
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    Hello, you know, I think that when there was something like an ocean or an ancient civilization on Mars.
    Space facts: Mars is the most similar in structure to earth.
    I am a supporter of the fact that once there was a civilization, since there are bare traces of rivers and oceans, and now it is empty, since they were killed by a disaster unknown to us.
    True, this is just a theory, but I believe in it.
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    Is there an experiment they could try on Mars, space or here that might simulate early Martian conditions? Just to get some idea of what happened to the water.
    All that belongs to human understanding, in this deep ignorance and obscurity, is to be skeptical, or at least cautious; and not to admit of any hypothesis, whatsoever; much less, of any which is supported by no appearance of probability...Hume
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    Quote Originally Posted by marmishgor View Post
    Hello, you know, I think that when there was something like an ocean or an ancient civilization on Mars.
    Space facts: Mars is the most similar in structure to earth.
    I am a supporter of the fact that once there was a civilization, since there are bare traces of rivers and oceans, and now it is empty, since they were killed by a disaster unknown to us.
    True, this is just a theory, but I believe in it.
    There is a new study* from the folks at NASA/JPL regarding water on Mars currently, and in the past. It provides new insight on the extent of atmospheric losses, and the amount present today.


    "New Study Challenges Long-Held Theory of Fate of Mars’ Water"

    * https://www.nasa.gov/feature/jpl/new-study-challenges-long-held-theory-of-fate-of-mars-water/


    Regarding any civilization evolving in the history of Mars, some would think it is unlikely. When one considers that Mars lost its magnetic field ca. 4 billion years ago, the solar radiation penetrating the atmosphere would have had a substantially negative impact on any evolving life forms. There would not have been sufficient time, it would seem, for the appearance of ancient intelligent life forms leading to such civilizations. But, like everyone else, this is only one guess about such a possibility.
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    “We knew for a long time that Mars was a wet planet in its early days, but it was unclear where all this water had gone,” said Dr. Peter Grindrod, a planetary scientist at the London Museum of Natural History. in an interview with the BBC. In the atmosphere of Mars, we found that at least some of this water has evaporated into space, and ice deposits on or just below the surface indicate that some of the water is frozen. "
    Given these comments, I am convinced once again that Mars once looked different, but I wonder how close to Earth. And if it looked roughly like our planet, then what entailed such consequences.
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