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Watch NASA’s Perseverance Rover Land on Mars! This Thursday 18 Feb :-)

Discussion in 'General Chit Chat' started by aposhark, Feb 15, 2021.

  1. aposhark
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    aposhark Well-Known Member Lifetime Member

    https://www.bbc.co.uk/news/science-environment-56119931 :
    "Post-landing analysis indicated the vehicle had come down about 2km to the south east of the delta feature in Jezero that Perseverance plans to investigate."
  2. Aromulus
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    Aromulus The Don Staff Member

    First case of Covid-19 registered on Mars............
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  3. Anon220806
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    Anon220806 Well-Known Member

    They seem to think they are close to some dunes, which can be problematic or so they implied.
  4. Anon220806
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    Anon220806 Well-Known Member

    I thought that too. I am sure they don’t let us know everything at anyone time. I am just hoping they can easily access the main delta as it has captured my interest.

    @aposhark Our 8 yo watched it all and cheered at the end when it landed along with them at the JPL centre. I gave her a bit of a commentary as she otherwise found the info coming from the NASA officers a bit tricky to get her head around.
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  5. Anon220806
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    Anon220806 Well-Known Member

    F79BB469-428D-4E25-94DA-A35E6B81FA50.jpeg 26643676-847E-4156-9C67-DD93859AB298.jpeg Vertical scale is actual. The white dots are the landing spot.


    606024B3-2097-41CD-A7FE-299E1F8A1AE7.jpeg 936E37F1-D290-42B3-9FB2-5E813B7A586D.jpeg CDFDDE9E-F6B8-48C4-8C63-4FAE2F81B30B.jpeg
    Last edited: Feb 19, 2021
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  6. oss
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    oss Somewhere Staff Member

    The likelihood is that these features are in the region of 3 to 4 billion years old, I was going to mention that the river delta looked quite mountainous would that be normal on Earth for that kind of topography for a delta? (bearing in mind that Earth gravity is about 3 times higher)

    The crater doubtless predates the lake that formed, but one thing I wondered is if there has ever been any evidence for plate tectonics on Mars at any time, that would be something that would be fascinating to find evidence for,
  7. Anon220806
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    Anon220806 Well-Known Member

    The Mississippi delta goes back 100 million years ago and it is pretty big. The size and amount of the deltaic fan is a reflection of the amount of work the river has done in eroding the hills and mountains it has passed through. On Earth there is the added factor created by uplift from the processes of plate tectonics that fuels the delivery of sediment to the fan somewhat more so.

    The deltaic fan of course is a reflection of Mars gravity, as as soon as the river entered the crater lake the speed of water flow slowed and the sediment dropped out under gravity. And the act of erosion by the river in the first place is as a consequence of gravity. It will be interesting to hear what NASA etc say about it.

    But yes. Colossal amounts of mountain eroding sediments can be deposited over millions of years.

    Drilling in the Gulf of Mexico reveals that such sediments can indeed be very thick. Thick enough to make it financially viable to exploit huge volumes of oil from within the deposits over a substantial vertical rock column.

    There is bound to be some Mars factors in the mix and am prepared for some surprises.
    Last edited: Feb 20, 2021
  8. aposhark
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    aposhark Well-Known Member Lifetime Member

  9. aposhark
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    aposhark Well-Known Member Lifetime Member

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  10. Anon220806
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    Anon220806 Well-Known Member

    I read somewhere that they believe the source of the water may have been thawed glacial deposits at the pole.
  11. Anon220806
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    Anon220806 Well-Known Member

    The delta deposits at the end of the Mississippi are 3000 feet thick.
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  12. oss
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    oss Somewhere Staff Member

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  13. oss
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    oss Somewhere Staff Member

    They think there is substantial evidence for an ocean on mars at one time, given that the sun was a lot cooler 4 billion years ago that implies a fairly thick atmosphere to create enough greenhouse effect to keep the water liquid, one of the other big questions is did Mars ever have a geomagnetic dynamo and when did it freeze as that sets the timescale for the start of the loss of the atmosphere and the as a result the loss of a lot of the water, although I think the believe that a significant amount of the water is still there sub surface.
  14. Anon220806
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    Anon220806 Well-Known Member

    Could it be possible that gravity on Mars was greater at some point in time?
  15. oss
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    oss Somewhere Staff Member

    No that's impossible, gravity is a direct product of mass.

    Mass bends spacetime, as planets accrete the gravity would gradually increase as more mass occupied one locality.

    Of all the four fundamental forces Gravity is quite special, one because it is so weak in comparison to the other three and secondly it appears to be a monopole i.e. there does not appear to be any antigravity.

    The only way a planet's gravity could decrease is if another planet hit it hard enough and fast enough to break it into two or more separate pieces that had enough velocity to escape the remaining mutual gravitational attraction and that would of course melt the entire planet and all of the bits it split into.

    For comparison Gravity is about 10^38 times weaker than the Strong force or Strong interaction, the Strong force is what holds nuclei together it has an incredibly short range.
    Last edited: Feb 20, 2021
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  16. oss
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    oss Somewhere Staff Member

    See my previous reply first but yes the gravity would be a tiny fraction less now due to the loss of the atmosphere and the water to the solar wind but we are talking umpteen decimal places and that would have happened over a period of probably a billion years or more after the dynamo stopped (if it ever had one).
  17. aposhark
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    aposhark Well-Known Member Lifetime Member

    One of your best, Jim ;)
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  18. Anon220806
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    Anon220806 Well-Known Member

    The moving waters or river (if that is what they were) would have been capable of transporting sediment over distance. Once arriving at the lake sediment will have dropped out albeit more slowly than here on Earth. But some kind of sorting will have occurred whereby the finer stuff would have settled furthest out from the crater rim and the coarsest nearer the crater rim. Sometimes further out than others depending on the energy in the river at the time, depth of crater water etc. So I am expecting the Jezero Crater fan to be sorted in such a way. Known as a Bouma Sequence here on Earth.
    Last edited: Feb 20, 2021
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  19. oss
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    oss Somewhere Staff Member

    Certainly looks like a river.
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  20. Anon220806
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    Anon220806 Well-Known Member

    So are these holes in the rocks worm holes or holes created by gases trapped within the rock? E4A6FD67-3556-4E13-B33A-8369525B6D77.jpeg

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