Martian dunes under the microscope

By Phil Plait | December 7, 2010 7:00 am

Sometimes, I see an image and do a double-take. This picture sure caused one:


[Click to barsoomenate.]

If I told you those were bacteria under a microscope, you might believe me for a minute or two. But actually, those are sand dunes on Mars!

Yup. It’s funny how bizarre and alien Mars can be. What you’re seeing in this image from the Mars Reconnaissance Orbiter HiRISE camera is actually two different kinds of sand: the dark stuff in the big dunes is actually made of grains of gray basaltic sand. They’re heavy and pile up into dunes. The ripply pinkish stuff between the dunes is made of smaller grains of sand laden with iron oxide — rust! The wind can shape those grains more easily, so they can form more gentle, smaller wavelike patterns. This is also why dust devils on Mars leave such amazing and intricate patterns.

Still, those dunes really look like microbes… and hey, wait a second. There are a set of characteristics that living things share: the ability to consume, excrete, multiply, and show complexity. Sand dunes consume, in a way: the wind brings in more sand to build them up. The excrete, too, by losing sand. They can grow, and split in half, making more. And in point of fact, they do show emergent complex behavior.

Maybe the dunes share more than just appearances with bacteria…could sand dunes actually be [dun dun dunnnnnn] alive*?

* No. Duh. C’mon.

Image Credit: NASA/JPL-Caltech/University of Arizona

Related posts:

Martian Swirly
Martian avalanche crashes the party
Another dose of Martian awesome
The Devil is in the details

CATEGORIZED UNDER: Astronomy, Pretty pictures

Comments (35)

  1. Chris

    You never know Phil. Remember “Ugly bag of mostly water.” Star Trek TNG for those not in the know.

  2. Wildride

    Dr. Manhattan would be pleased.

  3. Tom

    So not Silicon based life, but silica based

  4. “World-famous astronomer announces ‘There is life on Mars’! News at 11.”

  5. Chris

    There are a set of characteristics that living things share: the ability to consume, excrete, multiply, and show complexity
    So is fire alive?

  6. Nigel Depledge

    The BA said:

    There are a set of characteristics that living things share: the ability to consume, excrete, multiply, and show complexity.

    You missed out one of the most important aspects of living things: they form a boundary (i.e. they keep their insides in and the outside out).

    By your criteria, fire is alive.

    Oh, wait . . .

    “New plasma-based life-form discovered!”

  7. Nigel Depledge

    Huh. Cross-posted with Chris (5).

  8. “Arsenic discovered on Mars!” NASA today demanded a $gazillion budget to prevent extermination of terrestrial kindergarten teachers by Red Planet Metallo-Trelide death squads.

    David Obey, Chairman, House Appropriations Committee, “Is it not true that the only terrestrial kindergarten teacher killed by a spaceship was killed by a NASA spaceship?”

    NASA Administrator Michael Griffin replied, “Yes, but only in an empirical, literal sense.”

  9. noen

    Muad’Dib, we have wormsign.

  10. m5

    I’m surprised people here have never heard the old fire-is-almost-alive-it-just-doesnt-have-heredity argument.

  11. Mike

    The spice must flow.

  12. fernly

    You don’t mention the sharp-edged light boulders scattered over the top of the sand dunes. How do boulders get on top of a heap of sand? They had to be there first, right? There must have been some kind of a pavement, a continuous layer of brittle — lava? sediment? — which shattered into pieces as the sand was withdrawn from under it. Except that there doesn’t seem to be anywhere near enough white boulders to amount to complete coverage, so there must be a lot of white boulders sunk into the darker sand. And: what started the process of withdrawing the support from under the pavement?

  13. Lupine

    I can almost hear the Syfy channel movie of the week coming….

  14. Bob Hyden

    All that is missing are the Worms.

  15. Thanks for the post, Phil.
    But as far as I can see, the dark basaltic sand actually show the shortest wavelength ripples – both on the big black dunes, and in between the crests of the pinkish dunes.
    fernly @ 12: When you shake a tub of sand and gravel, the biggest ones will rise to the top, simply because the small grains of sand can sink into the space between the larger gravel. That is the reason farmers each spring find new rocks on their fields. The shaking is performed (mostly) by frost heaving – probably the same on Mars.
    Cheers, Regner

  16. JP

    So that face on Mars really wasn’t a monument but an *actual* face? Heh.

    We recently spent an hour-plus at one of the local Science on Tap presentations examining photos of Martian land features. Good stuff.

  17. Geb

    @13 Yep, It’ll be Shifting Dunes:
    “They thought they were off for a picnic at the beach, but really they were the beach’s picnic.”
    I really need to work on my Taglines…

  18. Keith Bowden

    “Barsoominate” – good one!

  19. Michel

    Just one question.
    What´s the scale?

  20. Michel

    “Maybe the dunes share more than just appearances with bacteria…could sand dunes actually be [dun dun dunnnnnn] alive*?

    * No. Duh. C’mon.”

    Crap can be black.
    Maybe it´s Martian guano. Made from the inside seeping and oozing outwards. And since Martian gravity is less than ours it can grow and grow and grow.

  21. Edward Carney

    Has to be one of the most thrilling Mars photos yet.

  22. Mike

    “NASA scientist says dune-sized bacteria alive on Mars.”

  23. Martian dunes debate wether orbiting lights are artificial or not…

  24. Pete Jackson

    Like many astronomical pictures, this one has the contrast cranked up way too high just to look snappy, so that the sand dunes actually look like completely black depressions (at least in my browser)! Perhaps this is what is confusing No. 12 fernly. By increasing the brightness and reducing the contrast, you can see the dark dunes for what they actually are: beautifully formed ripply structures lying on top of the rocky plain and, of course, covering up the rocks.

  25. Atreides

    C’mon, only 3 Dune references in 24 comments? Duke Leto II would be displeased, and you don’t want that.

    On a serious note, cool picture. What is the scale btw?

  26. Messier Tidy Upper

    Great image and I certainly wouldn’t have guessed Mars by looking at it. Those have got to be the weirdest sand dunes I’ve ever seen! 8)

    @ ^ Atreides : are you counting your comment in that? 😉

    The dunes of Mars would seem far safer than dunes of Dune where sandworms and space wars are concerned – and yet Martian conditions are actually far harsher and less hospitable atmosphere & pressure~wise.

    Still this picture certainly spices them up too! 😉

    I agree with Atreides on the need for a scale bar there too.


    PS. Did you know Arrakis (the real name of “Dune” in the Frank Herbert’s classic novel series) is a real star system name – for Mu Draconis a faint but interesting binary star – two F7 Procyonese dwarfs – located near the head of the “dragon” roughly in line with Rastaban (Beta Draconis) and forming a triangle with Kuma (Nu Drac). There is a slight confusion here in that the star Arrakis in the 1988 edition is also listed by the ‘Alrakis’ variant of its name in a later updated 2007 edition of Collins Guide To Stars & Planets, Ian Ridpath & Wil Tirion, Collins. (First published 1984.)

  27. Messier Tidy Upper

    See : for more info. on the real star via Kaler’s website


    for a photographic finder chart

    While this :

    is the wikipage for the fictional exoplanet. :-)

  28. Messier Tidy Upper

    @25. Atreides :

    Duke Leto II would be displeased, and you don’t want that.

    Do you think the God Emperor of Dune would have enough human humour left in him to let us worm our way of that thumping problem – and using the odd bad puns? 😉

    Incidentally, the Wikipedia page for Arrakis seems to say “Dune” orbits Canopus instead which I don’t remember from the novels & is much less plausible than the Mu Drac stars given the more massive white supergiants shorter lifespan and lesser likelihood of having planets. (Massive stars like Canopus are very hard on protoplanetary disks tending to destory them via excessive radiation.) Oh well.

  29. Jeff

    in a broad sense, they are alive. What is life? The universe itself is alive, anyone who loves this blog understands this.

  30. Gary Ansorge

    Dunes alive, that’s some cool pic there Phil.

    If we define life as a self replicating, self sustaining system, then living dunes might be possible but their energy input would appear to be limited to blowing winds,,,not too efficient in my book,,,

    “Living” plasmas would seem a great deal more probable. Though how they would pass on a genetic code, both mutable and stable, beats the heck out of me.

    Guess, I’ll just have to wait and see,,,

    Gary 7

  31. Brian Too

    You can walk there, but step in a broken pattern. Steady walking attracts the Shai-Hulud. Only a fool or a madman does that.

  32. Gary Ansorge

    31. Brian Too

    “Only a fool or a madman does that.”

    ,,,or somebody who can run really, REALLY fast,,,

    Gary 7

  33. Messier Tidy Upper

    …Or who can ride a sandworm Fremen style! 😉

  34. Gary Ansorge

    33. Messier Tidy Upper


    Gary 7

  35. Bademart

    Well, if life is chemistry… Is not all chemistry life of some sort?


Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!


See More

Collapse bottom bar