Another awesome Martian avalanche

By Phil Plait | March 15, 2010 7:44 am

Spring is approaching us here in the northern hemisphere on Earth once again, and we are experiencing the annual thaw of the winter ice.

Spring is approaching the northern hemisphere of Mars as well, and with it comes the thaw of carbon dioxide ice. Some of that dry ice sits at the tops of cliffs, and when it thaws it dislodges the material there. The rock and debris on Mars then does the same thing it would do on Earth: it falls. Fast.

And when it does, you get this slice of Martian awesomeness:


Holy scarp!

That’s another avalanche on Mars caught in the act by the HiRISE camera on Mars Reconnaissance Orbiter. I say another, because a few others have been seen, including this spectacular one two years ago, and lots of older ones that left their marks on the Red Planet’s surface.

This one is amazing! You can see the debris falling down the cliff’s edge (the top of the cliff is to the bottom left of the image, and we’re looking almost straight down the cliff’s face) and then creating a plume of dust at the bottom, hundreds of meters below. When HiRISE took this image, the slide couldn’t have been more than a minute old. If you look at the higher-res image (click the image above to embiggen) you can see that there have been a lot of avalanches here in the past, too. The bottom of the cliff has lots of material clearly deposited by fast-moving falling debris.

To be honest, it’s not completely sure that the sublimation (the change from solid directly to gas) of carbon dioxide is causing these avalanches, but it does seem the most likely explanation. Whether it’s dry ice or not, what this shows us directly is that Mars is still an active place. Certainly the surface is undergoing continual (if small scale) modification, with avalanches, meteor strikes, and other processes still occurring even, literally, today.

Mars is a very, very cool place.

If you want to learn more, check out the HiRISE blog, which always has great stuff, including explanations of these extraterrestrial rockslides.

And when you read about Mars and our exploration of it, remember this: it is an entire world, worthy of our attempts to understand it. And that is one of the grandest things we humans ever do.

MORE ABOUT: avalanche, HiRISE, Mars

Comments (34)

  1. UmTutSut

    Seriously. Cool. Phil, do you think the white streak above the dust cloud could actually be material caught in mid-fall?

  2. Niall

    Very cool stuff, it looks like the gas was released with some force. This, along with the general destabilisation caused by the dry ice melting, I would say its the most probable cause of the avalanches (I say this as neither a geologist or astronomer, biology is my forte).

  3. jb

    What a fascinating place!! Must be cool to be the first to look at the data when it first comes down!! compare it some before and after pics…

  4. Phil B

    Where is this? Is it happening at the ice cap or in one of the valleys/canyons further south?

  5. Wait, isn’t that Bigfoot in the bottom right?

    Heh, sorry. Very cool, Phil. Makes me want to climb that cliff.

  6. Aaron

    This is fantastic! It really brings the fact that Mars is not just some pretty orange jewel in the sky, but is indeed a whole new world, down to Earth . . . so to speak.

    It makes me wonder what else going on in the Universe!

  7. Pi-needles

    I think I’ve fallen for these Hi-Rise MRO images. 😉


  8. Captn Tommy

    I agree with UMTUTSUT, If you look closely at the Embiggined picture the entire rim of the cliff seems to be cracking. Then if you follow the first dark umber band (wide ledge) to the right of the edge you can see two edge pieces to the left and right of the major fall. The one to the left looks like a splash (pointing downhill) the one to the right looks like a white coated piece of edge just about to hit the Umber ledge.

    1. This looks like a cornace (over hung snow ledge) collapse just like snow in the Rocky Mountains, USA. The fall of a major protion will shake ather pieces of cornace loose.

    2. If only we had some quake sensors we could get some really nice local readings.


  9. QuietDesperation

    I see a piece of wood with white paint and a patch of mold.

  10. Peter Davey

    To quote the Bard: “Hot ice and wondrous strange snow.”

    If they can perform “Hamlet” at Elsinore, perhaps one day, they’ll be able to perform “A Midsummer Night’s Dream” at a location even more exotic than the one Shakespeare devised.

  11. Chip

    If one were standing a good distance away from the base of the cliff and had a microphone for external sounds built into the spacesuit, I wonder how the avalanche would sound. Low rumble? Or or maybe higher due to a thinner atmosphere. Whatever it sounded like, it would be awesome to see with the huge plume billowing at the base.

  12. Mik C.

    Great photo, but the blue stuff on the lower left looks suspiciously like a sea of stucco. Ergo, Mars is man made, and fairly recently too.

  13. kevbo

    “When HiRISE took this image, the slide couldn’t have been more than a minute old”

    Are you sure about this? I’m no astronomer, or geologist (I don’t even play one on TV), but the gravity there is weaker than on earth, and the atmosphere a lot thinner. Wouldn’t it take longer for dust to settle there?
    Are there any simulation tools to run on this?

  14. Mike Sperry

    Reminds me of parts of New Mexico.
    It probably says more about my pop-culture touchstones, but when I saw that image my first thought was “when the dust cloud clears, there’s going to be a Wile E. Coyote-shaped hole in the ground”.

  15. @ Chip:

    I was wondering the same thing. I suppose it’s like talking after inhaling helium. The timbre would be shifted upward because of the lower density of the atmosphere. But if any big blocks came tumbling down, you’d feel the impact transmitted through the ground. Kind of like a bitchin’ sub-woofer.

  16. Rift

    This is one of the most amazing things I’ve ever seen. Who would have thunk we’d actually catch one of these suckers *happening*, or shortly thereafter.

    People may bemoan the lost (or potential lost) of man spaceflight, but I’ve seen some seriously cool things in my lifetime, starting with dust clouds on mars with the early Pioneers.

    @14 Mike Sperry, lol. But damn it I had to wipe sprite off my screen.

  17. !astralProjectile

    kuhnigget and Chip: Maybe, but I’m not sure. The fact that it is CO2 (with it’s greater degrees of freedom) might trump the thin atmosphere.

  18. To be honest, it’s not completely sure that the sublimation of carbon dioxide is causing these avalanches, but it does seem the most likely explanation.

    uh, Phil, it’s my experience that gravity is the main culprit in these avalanches.


  19. Menyambal

    When I look at this image, and especially the ones from the previous post, I do not see landslides or avalanches, as much as I see localized downslope winds. From Wikipedia: “Katabatic winds are most commonly found blowing out from the large and elevated ice sheets of Antarctica and Greenland. The buildup of high density cold air over the ice sheets and the elevation of the ice sheets brings into play enormous gravitational energy, propelling the winds well over hurricane force.”

    I can’t get a good graph, but I think that freshly sublimated CO2 gas is a lot colder and denser that the surrounding atmosphere, even if that, too, is CO2, especially on a “hot” spring day. Which should give katabatic flow.

    I am saying that cold, dense pools of CO2 gas pour over the edge of the cliff and blow up dust. The wind may even cause rocks to slide, but the trigger is not just the shrinkage or disappearance of solid CO2, but the movement of very cold, dense CO2 gas flowing downhill.

    You can see flow patterns in the whitish snow along the bottom of the cliff in some images. Dense gas is probably flowing down all the time. But every now and then, a big pool or cloud of very cold gas goes over all at once, maybe through a channel or something. The dust cloud from the avalanches is low and flat and goes out, away from the cliff, instead of rising up and hiding the main part of the “landslide”.

    I know that CO2 clouds flow downhill here on Earth, see Lake Nyos, but I do not know what would happen in a CO2 atmo such as Mars has. Can anyone say or show how dense CO2 is at various temps? I know we get Katabtic winds, here, from temperature differences, but I can’t work up numbers for Mars.

    Help? Speculation?

  20. Rift

    Cool interpretation Menyambal, I’m not anywhere close to an expert but I know CO2 does some strange things flowing down hill. Can’t help you with the speculation, but whatever the cause it is still hellavu awesome pic.

    And why don’t Phil”s awesome astronomy posts get as many comments as his vaccines/global warming/crazy texan SBOE members do???

  21. Chris Sol

    So, is the white stuff in the bottom left of the image really a big ol’ CO2 ice sheet?

  22. John Baxter

    I would prefer that this “Spring is approaching the northern hemisphere of Mars as well” read “Spring happens to be approaching the northern hemisphere of Mars as well”

    We here know it’s a coincidence…many of the the folks reading over at CBS likely don’t.

  23. ProofByInduction

    I think the photos are great, but…I find myself a tad annoyed that no one has turned the picture so up is up and down is down, so I stuff the picture in a viewer and rotate it. I guess as a geoscientist I’m more used to looking at stuff gravitationally oriented!

  24. Pustle

    This is the direct result of Global Warming on Earth. Has Al Gore been notified? Has the film been offered to Al for another exploitative film and Nobel Prize? Why have you been trying to squash his only source of serious income? Is it possible that the introduction of human designed and developed machines into the Martian environment are causing all of the anomolies?

  25. Markle

    Very cool. I forget where I read it(poss. Emily’s post?) but there are supposed to be 4 separate rock falls visible in that photo. I see what looks like a second off to the left, but I couldn’t see the others.

    On the Cumbrian Sky blog (doesn’t (s)he post here?), (s)he found some awesome landslide scenery in the Mars side of Google Earth. At S 7° 37′ 08.28″, W 41° 21′ 33.54″ there’s a 2 mile wide crater that has been half disappeared by the cliff face of Ganges Chasma. Open Google Earth and go to View>Explore>Mars. Paste the coordinates above into the search bar and zoom in to 50mi or so

    I prefer my view which takes in 2 large slides and 3 medium ones. Create a bookmark(pushpin) and paste these values into the view tab:
    Latitude: S 7° 49′ 38.76
    Longitude: W 41 24 37.56
    Range: 41838m
    Tilt: 45°

    Now click OK. and possibly click on the pushpin to get GE to zoom

    See how the two large slides met in the middle of the gorge with the South slide overlapping the North. Check out the medium slide over in the lower left. It’s got a half mile wide crater in the slide with a twin outside the slide. Very different profiles. Wait… 1/2 mile wide? Go hover your mouse over the rim of that first crater on the canyon wall. Look at the elevation. 2600ft elev. Now hover over the bottom of the slide. 12,000ft. That’s almost 3 vertical miles that that rock fell! That cliff face that you see posted above, a mere 2200ft

    Back on Earth, Earth Observatory posted pics from their satellites of the slides in Italy last week. In the description, they posted a link to video of one of the slides while it happened.

    Top of the slide ~900ft
    Bottom of the slide ~700ft
    That’s an order of magnitude between each, roughly. 1.86 total, if you’re persnickety.
    Although each takes up about same amount of real estate on your screen, each is about 10 times the size of the next smallest in real real estate.

    Edit: size attributes don’t seem to work here in comments :-/

  26. MaDeR

    Great, yet another climate troll. Yeah, I know, do not feed trolls etc, but I am bored.

    “This is the direct result of Global Warming on Earth.”
    No, it is not. You know it, I know it. Was it feeble try to be sarcastic?

    “[bunch of rethorical charged pseudoquestions]”

    If I understand corrctly, Pustle’s line of thinking goes like this: Earth and Mars have for all intents and purposes indepedent climate. So any unusual happening on Mars PROVE!!!111oneone that GW on Earth is bunk. Somehow. In some… way. Really. It is magic people!

    Now my head hurts. Crackpot logic is dangerous to sanity.

  27. Georgijs

    When I was little i thought that the only changing place is Earth and the rest of the planets where static (like statues). HA! Boy was I wrong! And here comes one of my favorite phrases: Live and Learn. An awesome picture. It is amazing that we are able to look at Mars’ surface and see the changing environment there.


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