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Gorgeous Images: Ancient River on Mars?

Perspective view of Reull Vallis. Credit and Copyright: ESA/DLR/FU Berlin (G. Neukum)

A computer-generated perspective view of Reull Vallis was created using data obtained from the High-Resolution Stereo Camera (HRSC) on ESA’s Mars Express. Credit and Copyright: ESA/DLR/FU Berlin (G. Neukum)

The Mars Express has long been taking pictures of what appears to be an ancient riverbed on Mars. In fact, Reull Vallis was one of the first objects on the Red Planet that Mars Express ever imaged back in 2004 when the spacecraft arrived in orbit. The latest images show the sinuous river-like feature that stretches for nearly 1,500 km across the Martian landscape. This winding depression is 6-10 km wide, and its depth varies from 100-600 meters. In comparison, the Amazon River on Earth is about 6,500 km long and 11 km wide in places.

So, is this really an ancient river?

High-Resolution Stereo Camera image of Reul Vallis taken on May 14, 2012 by ESA’s Mars Express. Credit:  ESA/DLR/FU Berlin (G. Neukum)

High-Resolution Stereo Camera image of Reul Vallis taken on May 14, 2012 by ESA’s Mars Express. Credit: ESA/DLR/FU Berlin (G. Neukum)

Planetary scientists seem to be fairly unanimous that, from orbit, this appears to be a riverbed. There is a system of tributaries and side channels that all appear to flow into the huge Hellas Basin.

There are various theories as to how it may have formed, however. Some scientists say that this feature may have been created quickly in a sudden deluge or runoff event, as the entire system look like stream beds cut by sudden runoff in desert regions on the Earth.

Reull Vallis in context. Credit: NASA MGS MOLA Science Team.

Reull Vallis in context. Credit: NASA MGS MOLA Science Team.

Others suggest this system consists of parts that were formed during several phases rather than being a single continuous channel, and likely had independent formation phases and different sources of water. For example, numerous crescent-shaped features could be older craters distorted by water flow.

There is also evidence of deposits of volatiles in the walls of the channel that could be ice.

In the wider context image above, the tributary intersecting the main channel appears to be part of a forking of the main valley into two distinct branches further upstream before merging back into a single main valley.

The right (northern) part of the main image is dominated by the Promethei Terra Highlands with their high and soft-rounded mountains shown in these images, rising around 2500 m above the surrounding flat plains.

The perspective view below shows one of these mountains with nearby sediment-filled impact craters:

This computer-generated perspective view shows part of the Promethei Terra highlands adjacent to Reull Vallis. Credit: ESA/DLR/FU Berlin (G. Neukum) >

This computer-generated perspective view shows part of the Promethei Terra highlands adjacent to Reull Vallis. Credit: ESA/DLR/FU Berlin (G. Neukum)

What about lava flow? Could this be a giant lava flow or tube that has collapsed? Astronomers say that lava and glacial erosion would have produced very different channels.

And so it appears Reull Vallis provides evidence of past water on Mars. And if so, it means that the planet’s climate has changed dramatically since these features were formed between 3.5 billion and 1.8 billion years ago.

One of the first images taken by Mars Express in 2004 of Reull Vallis. Credit: Credit: ESA/DLR/FU Berlin (G. Neukum)

One of the first images taken by Mars Express in 2004 of Reull Vallis. Credit: Credit: ESA/DLR/FU Berlin (G. Neukum)

Sources: ESA Science paper from 1997 by Scott Mest and David Crown, University of Pittsburgh, Paper by Kostama, et al, 2007, ESA 2004.

About 

Nancy Atkinson is Universe Today's Senior Editor. She also works with Astronomy Cast, and is a NASA/JPL Solar System Ambassador.

Comments on this entry are closed.

  • Torbjörn Larsson January 19, 2013, 1:14 PM

    Interesting comparison. The Amazon river is ~ 20 – 50 m deep, ” in some places as much as 100 metres”. http://en.wikipedia.org/wiki/Amazon_River

    • Shootist January 20, 2013, 4:06 PM

      I hesitate to compare this ancient water course with any Earthly river, as there are damn few 10 km wide rivers. However, something like the Lake Aggasiz out pour channels would be more visually similar and probably more accurately describes Reull’s origin as a vast drainage ditch.

      The topographical similarities between the de-glaciating Earth and this part of Mars are striking.

      http://www.lacussomniorum.com/leverington_teller_2003_CJES.pdf

  • Justin Case January 19, 2013, 2:55 PM

    This is not the remnant of an ancient river. This depression was formed by the movement of tectonic plates on Mars.

    • Jeffrey Scott Boerst January 19, 2013, 6:02 PM

      …and your response, trumping the community of planetary scientists’ conclusion is based on……?

      • Justin Case January 19, 2013, 7:28 PM

        The Akashic records.

        • Torbjörn Larsson January 20, 2013, 12:50 PM

          Ah yes, religious texts* are relevant – not. They also support homeopathy, do you think that trumps physics and medicine too?

          * Blavatsky’s theosophy, leaking into Steiner’s anthroposophy – both founded by known scammers.

          • Justin Case January 20, 2013, 1:27 PM

            Get a sense of humor and the Akashic record is not a religious text. It’s mentioned in ancient Hindu religious texts but it is not a religious text.
            Nobody knows for absolute certain what that depression is. It’s all speculation at this point. It could just as well be caused by a Marsquake, wind or any other number of things.

        • meekGee January 20, 2013, 3:45 PM

          I just had to look:
          http://en.wikipedia.org/wiki/Akashic_records

          “People who describe the records assert that they are constantly updated automatically and that they can be accessed through astral projection”

          Can’t really argue with that….

          • Justin Case January 20, 2013, 4:49 PM

            “….knowledge encoded in a non-physical plane of existence.”
            The universal server of all truth. IP address – 000.000.000

          • meekGee January 20, 2013, 5:28 PM

            Amen, brother!

    • lcrowell January 20, 2013, 6:35 PM

      I don’t think this is a tectonic rift or plate boundary. I am not a planetary geologist by any stretch, but if I had to make a statement I would say the Valles Marinaris is maybe a sort of proto-tectonic rift zone similar to the mid-Atlantic rift. More data has to be found, but I suspect that Mars never fully developed tectonic properties.

      LC

    • Troy January 20, 2013, 4:16 PM

      Perhaps, we need to assess the idea that humans came from Mars, as an
      advanced species, and when our technologies failed, we had to return to a
      life of lower technology. The idea is we left Mars due to an imminent
      asteroid/meteor barrage that would render the planet lifeless .. much as
      what is being theorized happened to the dinosaurs on Earth. A few large
      asteroid/meteor impacts and you get a “nuclear” winter, and an ice age
      can begin. Mars is riddles with HUGE asteroid craters. That many would
      certainly wipe out an entire planets ecosystem. Add to that a shift in
      the planets orbit OR our sun cooling down and over a few millions
      centuries you get Mars.

  • Paul Delange January 19, 2013, 7:01 PM

    The river bed has no crater impacts, so it must be more recent then those craters.

    Thus it seems the river flowed gently beside that beautiful martian landscape at some point in the past. What I would do to see video of that!!

    Beautiful images, thank you ESA.

  • Aqua4U January 20, 2013, 12:46 AM

    I would so like to take a walk inside Reull Vallis! Or maybe not? Dust depth dependent

    • Skipdallas January 21, 2013, 9:20 AM

      With the low atmospheric pressure, the only thing the dust would do to you would be: Abrade your suit, then your skin. Of course you would already be dead long before your skin…. well.. abraded.
      Bon Voyage !
      PS
      Take a sweater

  • Skipdallas January 21, 2013, 8:48 AM

    Water on Mars? Why would anyone think such? Of course we can now see that nowhere but Earth has ever had water/life/brains/understanding! This small planet is unique in and of itself! In the whole of the Cosmos! My Priest told me so! So There! ROTFLMFAO!
    Wait! Mars you say? May have WATER? And maybe LIFE? Ahh! OK! it is all dead now.

    But wait: if it was before, then it may be again? I guess we may need to………………

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