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Thread: Another shot from the hip by NASA? Gravel on Mars

  1. #1 Another shot from the hip by NASA? Gravel on Mars 
    Moderator Moderator Dishmaster's Avatar
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    The latest NASA press release seems to confirm the presence of water and rivers on ancient mars.

    NASA - NASA Rover Finds Old Streambed on Martian Surface

    The article is written in a way that this is the only possible explanation. But with the negative experience we have with previous NASA announcements (bacteria seemingly incorporating new elements in their DNA) one may question the firm statements made there. So, here is a question to those who also have a geological background.

    My first impression was that the gravel shown looks quite different from what I would expect to see in a river bed. Aren't alternitve explanations equally justified, like sandstorms shaping the surface of stones? In addition, could the conglomerates shown not also be a result of volcanic activity?

    What disappoints me most, is the common habit of so called science journalists, who simply copy and paste such announcements without actually looking deeper or trying to get confirmation from independent researchers. I don't understand that they do not realise that press releases do not necessarily transport firm knowledge or confirmed scientific results, but instead are merely advertisements to catch the attention of the public.


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  3. #2  
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    The gravels in conglomerates at both outcrops range in size from a grain of sand to a golf ball. Some are angular, but many are rounded.

    "The shapes tell you they were transported and the sizes tell you they couldn't be transported by wind."
    I disagree. I think the sizes tell us they couldn't be transported rapidly, by wind.

    Try this: Suppose somebody lost a golf ball on Mars 4.5 billion years ago. Allow the shifting of sand and dust by wind, around and under the ball, to insinuate it 3 horizontally each day. That'll be a paltry millimeter of transport each year. But transport it is. At that rate the golf ball will have traveled a quarter of the way around Mars when we find it. Whether or not a golf-ball (or brick?) would move at all on a bed of slowly shifting sand and dust, is maybe a physics question? I guess it would, and the folks behind the article just can't grasp the timescales at work on that planet's surface, like people who find fossil seashells in the mountains and suppose a great flood transported them there.


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    There was more detail in the televised press conference. I'll find a link.
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    Administrator KALSTER's Avatar
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    This doesn't look like wind transported, does it? Look at the comparison:

    692158main_Williams-3pia16189-43_946-710.jpg
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

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  6. #5  
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    Quote Originally Posted by KALSTER View Post
    This doesn't look like wind transported, does it? Look at the comparison:

    692158main_Williams-3pia16189-43_946-710.jpg
    But maybe polished by wind and sand? Would vulcanism be able to serve as a transport vehicle? What about these conglomerates:
    https://en.wikipedia.org/wiki/Pyroclastic_rock

    And then eroded over millions or even billions of years. I'm just asking.
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    I am no expert of course.

    Just saying with the comparison, it looks pretty plausible as a stream bed, especially with the different coloured rocks and the way they seem to have been cemented together like that. I don't think NASA is proclaiming certainty either, just good confidence. Supporting evidence are topography images indicating "an alluvial fan of material washed down from the rim, streaked by many apparent channels, sitting uphill of the new finds.", as well as the images taken by the Mars Reconnaissance Orbiter indicating evidence of flowing water.

    It is of course quite possible that simple wind erosion could have sculpted the rocks. Even though Mars has a thin atmosphere, it is still prone to severe sand storms that can move a lot of material around the surface. I guess we'll know more once they start analysing the rock composition.

    I do get your point about how they conduct their press releases though. If it happens that they change their minds later, it reflects badly on NASA and science generally in the minds of the average citizen, which in turn could affect funding in future.
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

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    One telling factor was how rounded the rocks are. Air transport would not have produced cobbles so smoothed, from what they said (there were other close ups of detail).
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  9. #8  
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    Quote Originally Posted by Dishmaster View Post
    The latest NASA press release seems to confirm the presence of water and rivers on ancient mars.

    NASA - NASA Rover Finds Old Streambed on Martian Surface

    The article is written in a way that this is the only possible explanation. But with the negative experience we have with previous NASA announcements (bacteria seemingly incorporating new elements in their DNA) one may question the firm statements made there. So, here is a question to those who also have a geological background.

    My first impression was that the gravel shown looks quite different from what I would expect to see in a river bed. Aren't alternative explanations equally justified, like sandstorms shaping the surface of stones? In addition, could the conglomerates shown not also be a result of volcanic activity?

    What disappoints me most, is the common habit of so called science journalists, who simply copy and paste such announcements without actually looking deeper or trying to get confirmation from independent researchers. I don't understand that they do not realise that press releases do not necessarily transport firm knowledge or confirmed scientific results, but instead are merely advertisements to catch the attention of the public.
    As far as I could tell by my readings, the basis for their decision concerning an old river bed is simply appearance. We know there is water ice on mars today under the polar frozen CO2. We have seen it in our rover digs.

    It would be very surprising if mars did not have much water in the distant past based upon our theories of stellar and solar system formation and evolution, along with Mar's proximity to Earth and the ice moons of Jupiter on the inside and outside respectfully, of its planetary location. I also expect that we will someday find large reservoirs of underground water and water ice on mars. Although it is conceivable that there might be another explanation for the appearance of this surface other than as a riverbed, I think the riverbed idea is by far the most likely reason for the observed rock agglomerations, rounded stones, striated channels, riverbed, and stream-like appearance and characteristics.
    Last edited by forrest noble; September 29th, 2012 at 11:34 PM.
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    It seems that the public is already losing interest in Curiosity.
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    Here is a video that pretty convincingly shows evidence that this finding is in fact caused by ancient water flow. Curiosity is at the base of an alluvial fan, a fan shaped deposit of sediment caused by the flow of water. The video compares Earth features to the feature we have found on Mars.

    NASA - Multimedia - Video Gallery
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  12. #11  
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    Quote Originally Posted by Jim Colyer View Post
    It seems that the public is already losing interest in Curiosity.
    I don't know if that is correct or not, at the present time, but I often get the feeling there is a very good chance that anything the public quickly loses interest in is of some considerable value.
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  13. #12  
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    There is another video on the Curiosity video gallery here
    NASA - Multimedia - Video Gallery
    where the reports are presented in a somewhat more cautious way. Thanks for all the comments!
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  14. #13  
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    Quote Originally Posted by Jim Colyer View Post
    It seems that the public is already losing interest in Curiosity.
    The public has a notoriously short attention span.

    Those of us in the sciences are most assuredly not losing interest in this mission. The public will be brought back around each time something new and interesting surfaces. Most of us can't be bothered to sit through a 2 hour movie if it gets boring, so it's a bit much to expect those people to sit around for months glued to their computer screens while NASA analyzes data feeds.
    "Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us." -Calvin
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  15. #14  
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    Fact is, it's a 2 year mission, and they will not get to Mt. Sharp for a year. No good for the twitter crowd. Not so bad for anyone really interested in science.
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    They always put down Percival Lowell and his canals on Mars. It occurred to me that he was seeing the ancient river beds that NASA talks about.
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  17. #16  
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    No he wasn't. They are far smaller than can possibly be resolved from earth.
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  18. #17  
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    Plus, he sketched out the canals he said he saw and they don't match up with any observations.
    Disclaimer: I do not declare myself to be an expert on ANY subject. If I state something as fact that is obviously wrong, please don't hesitate to correct me. I welcome such corrections in an attempt to be as truthful and accurate as possible.

    "Gullibility kills" - Carl Sagan
    "All people know the same truth. Our lives consist of how we chose to distort it." - Harry Block
    "It is the mark of an educated mind to be able to entertain a thought without accepting it." - Aristotle
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