Spectacular sand pit found on Mars!

By Phil Plait | August 18, 2011 12:50 pm

Check. This. Out: a perfectly-formed collapse pit on Mars that leads to an underground cavern!

Amazing! [Click to barsoomenate.]

This was taken by the Mars Reconnaissance Orbiter in July 2011. See the hole in the bottom? You can tell from the lighting that this is an underground opening to a cavern — a skylight. Quite a few of these have been found on Mars, actually. We see them on Earth and even on the Moon. Given the angle of the shadows, the vertical distance from the bottom of the pit to the floor of the cavern is about 20 meters (65 feet). Watch your step!

Here’s how we think skylights like this form. In the distant past, Mars was geologically active. Rivers of lava ran across the surface. If the surface of the lava hardens it can form a roof, allowing the lava underneath to continue flowing; these are called lava tubes and there are bazillions of them in Hawaii, for example. Eventually, the source of the lava chokes off and the lava flows away, leaving the empty tube underground. If the roof is thin in one spot it can collapse. Sometimes that just leaves a hole, but apparently in this case it was under a sand field. Some of the sand must have fallen into the chamber below and eventually blown away, leaving the pit and the hole. The pit is located not too far from Pavonis Mons, a known (long-dead) Martian volcano.

The hole is about 35 meters (115 feet) across, so the pit is about 175 meters (nearly 600 feet) across the rim. I love how it sits in an otherwise nearly featureless sand field; the contrast is beautiful. In the high-res image you can see boulders perched on the pit wall, having rolled part of the way down as well. The inside of the pit has lines and furrows that are instantly recognizable to anyone who has tried to dig a hole at the beach and had sand continually flow down from the rim.

It would be incredible to see something like this up close. It’s possible eventually someone will: such lava tubes would make good homes for future Mars explorers; they’d be protected from sand storms, temperature swings, and solar radiation (which is worse than for us on Earth because Mars doesn’t have a strong magnetic field to protect it).

… but you couldn’t pay me enough to go inside one of those. I have no desire to be slowly digested over ten thousand years.

Image credit: NASA/JPL/University of Arizona. Tip o’ the light saber to reddit.


Related posts:

More Mars caves found
There’s a hole in the Moon!
Spelunking the lunar landscape
Martian dunes under the microscope

CATEGORIZED UNDER: Astronomy, Pretty pictures, SciFi, Space

Comments (69)

Links to this Post

  1. Cavernas Bajo Marte. | Pablo Della Paolera | August 19, 2011
  2. Martian Sand Pit of the Day - TDW Geeks | August 19, 2011
  3. Monday morning links « mathbabe | September 12, 2011
  1. LSandman24

    “Boba Fett!? Where?” /cue Wilhelm scream.

  2. SkinnyDennis

    Any chance this is an impact crater over a lava tube with a collapsed roof? Seems like there’s at least a bit of crater rim above the terrain. Did the sand blow in the plain after the impact?

  3. JohnCarter

    “Barsoomenate” …I see what you did there

  4. Eleri

    11 year old developmentally delayed daughter: “Whas that mommy?”
    Me: “It’s a hole on Mars”
    Daughter: “Dah not Mars, it not red!”

    Had to explain about black and white pictures to her, and then show her colour pictures of Mars. :)

  5. Steve

    I love that I thought of the Sarlacc – and so did the previous poster.

  6. Darned kids and their BB guns. If I catch those little…

  7. Just to clarify… we’re all talking about the ORIGINAL Sarlacc, not that CGI-enhanced one with the extra tentacles right? Better be.

  8. Sawdust Sam

    Are you sure it’s not a giant molehill with a hole in the top?
    There is life on Mars!

  9. Arthur Maruyama

    Isn’t there a slight raised rim on the outside edge? Rather than being formed just by a lava tube collapse making a skylight, could this have been the result of a meteor impact which happened to punch into a lava tube?

    I suppose that a raised rim could have been formed by some wind phenomenon, but if so that explanation is beyond my capabilities to explain why the dispersal of the Martian regolith seems to be so symmetrical. I would assume that there would be prevailing winds in some particular direction which would force some asymmetry.

  10. Rick

    I don’t see a rim, perhaps a slight downgrade from the plain before you hit the pit itself. Given the sun angle, I think any raised rim would be more obvious — look at how sharp the contrast is for the little circle of slump inside the pit a quarter of the way down.

  11. Pete Jackson

    I would expect dust from the frequent Martian duststorms to blow in the hole, and eventually fill in the cavity. The implication is that the bottom of the pit has collapsed relatively recently (last thousand years, say) in Martian history.

  12. CB

    My first thought wasn’t Sarlac but rather Giant Martian Sand Lion. Of course a sand lion would be sitting in sand in a pit they made themselves, not in an exposed lava tube… But like I know anything about Martian sand lions!

  13. Yojimbo

    Clearly that is where they launch the tripods.

  14. Steve

    Oh yes the non-CGI Sarlacc. Only original, only classic! I would never live in the 24th century. Oh, wait…

  15. QuietDesperation

    It’s possible eventually someone will: such lava tubes would make good homes for future Mars explorers; they’d be protected from sand storms, temperature swings, and solar radiation

    And think of all the exercise they’ll get digging themselves out of the sand every other day.

    I dunno, but my first suggestion for a base location wouldn’t be “Hey, how about in that big sand funnel surround by the endless supply of sand?”

  16. Chief

    Nice to know you have read the Carter series on Mars for the barsoomenate reference.

    I wonder how far you have to go underground before the pressure gets up to a reasonable level. (or is the existing pressure at ground level not enough to matter much).

  17. QuietDesperation

    BTW, has Richard Hoagland seen this as evidence for his hyper dimensional whatsis civilization thingamagummy on Mars, or has he moved on to other things?

  18. Bob

    Lava tubes? bah! This is the main entrance to the crystal tube subway system.

  19. Trebuchet

    That’s an awesome photo! I’m picturing the sand at the bottom being in a conical heap, almost inverting the shape of the pit.

    And I guess I’m somewhat pleased that I’m not enough of a geek to know the name “Sarlacc”, even though that was the first thing I though of.

  20. Mejilan

    Wooooow, that’s pretty incredible!

  21. Freerefill

    If it had sand fill it in, and by the looks of it quite a bit, then shouldn’t the original hole be deeper than as measured by the shadow? Furthermore, if you consider years and years of sand being blown across it, falling into it, and not getting out, that pit could be much MUCH deeper.

    It’s great that more of these are being discovered. I’d LOVE to see a whole civilization on Mars, living in the ancient volcanic tunnels.

  22. Do I really want to see the ant lion at the bottom?

  23. Pat

    I bet that hole leads to the forgotten catacombs where the atmosphere-generators are. Or an ancient temple that contains a gateway to Hell. One of those.

    But most certainly not an underground city full of four-armed bug-people. That’s just crazy.

  24. Keith Bowden

    Boba Fett was a whimp. Vader collected Solo for him, he tripped over himself, screamed like a little girl and fell into the Sarlacc’s mouth. Maybe it was really his cousin, Curly Joe Fett…

  25. Chris

    Is this supposed to be black and white picture. Maybe it’s just my brain playing tricks on me (or I need a new monitor), but there looks to be a little color there.

  26. @lsandman24:

    Props for the Wilhelm reference!

    Aiiieeeeee!

  27. Pasander

    If I went to Mars, I would definitely want to investigate this location. And like Pete Jackson said, this feature seems relatively recent (given that millions of years of sand storms would surely have filled it up already).

  28. Skip Huffman

    Is this true color? the hint of blue around the upper right, at the crust partway down the slope has a hint of blue. This really looks more like a snow field than a sand field. with two crusts in the pack, one about half way down and the other at the bottom. A bit of a heat source could both cause the hollow and keep it clear of fallen snow. Do we have any thermal imaging of that feature?

  29. BJN

    And the giant Martian antlion continues to patiently wait…

  30. CB

    Yay, another one who thought of antlions! Wait… I said sand lion up above there. WTF? There’s no such thing, CB, you moron.

  31. That’s not a Sarlacc pit. That’s the entrance to the Ice Warriors’ underground city. It’s from there that they look upon our world with envious eyes.

    @LSandman24: I bloody hate the Wilhelm Scream. Nothing takes me out of a movie faster than hearing it.

  32. Digital Atheist

    I Baroomemated, yet I see no thoats or swarms of green Martians… nor even red Martian princesses in distress…

  33. Chris A.

    “…the vertical distance from the bottom of the pit to the floor of the cavern is about 20 meters (65 feet). Watch your step!”

    But under Martian gravity (0.376 g), it would be no worse than falling from 7.6 m (25 feet) on Earth, by my calculations. Survivable, but probably a little uncomfortable. Of course, given that the walls of the pit appear to be near the angle of repose, I’ll bet your landing would be on nice, soft sand that’s been sliding down the sides making a pile at the bottom for some time.

  34. Crux Australis

    I understand how illusions work, but I *cannot* see that image as anything other than a volancoesque mound with a hole at the top.

  35. alfaniner

    I instantly heard an angelic/demonic wail (“That sound!”). This is practically a frame from the film!
    (Do I have to say which one?)

  36. jess tauber

    My God! It’s full of stars! Nah, them’s just sand grains shining in the sun, Dave. If you hadn’ta disconnected HAL’s core memory and processing he might have told you that, dummy.

  37. mike burkhart

    I think the biger question is Have the volcanos erupted any time recently?I don’t think we could see it from Earth. In H.G. Wells War of the Worlds I found it funny that Astronomers on Earth could see the Cylinders lift off form Mars in telescopes.

  38. james
  39. Chris

    @Chris A.
    Falling only 25 ft on Earth is nothing? OK go walk blindfolded on your roof and let me know how that goes!

  40. truthspeaker

    I concede that “barsoomenate” is funny.

  41. Douglas Troy

    I have been sitting here watching that image for hours now … I think the Ant Lion is a “no show”…

  42. Das Boese

    @Keith Bowden Says:

    Well, to be fair he did eventually manage to free himself.

    …by detonating his jetpack.
    And digging himself out from below a couple meters of sand.
    And walking through the Tattooine desert, half naked, with broken bones, wounds from the explosion and covered in acid burns.

  43. Das Boese

    @mike burkhart Says:

    “I think the biger question is Have the volcanos erupted any time recently?”

    We haven’t directly observed any volcanic activity on Mars, but we found some indications of it happening within the last few million years, which is pretty recent in geology.

    http://en.wikipedia.org/wiki/Volcanism_on_Mars#Current_volcanism
    http://www.space.com/198-mars-volcanoes-possibly-active-pictures-show.html

  44. Booker_53

    I saw this movie!

    The Martians landed in a sandpit, and pulled people down through sink-holes, the implanted control devices in their brain stems.

    An eleven year-old kid sees it all happening.

    So that is their original sand-pit!

    It all comes clear!

  45. Digital Atheist

    AH! Tales from the Mos Eisley Cantina. ;-)

  46. alfaniner

    @44Booker_53 Glad somebody else remembers it! Invaders from Mars for those playing along…

  47. the_Butcher

    That’s not a hole…

    Crater’s shadow + comet’s remains (dark)

  48. Elfino

    I said it before with other nick, some years ago. I insist: there is a specific name for that geological feature. In the canary islands those holes are called “jameos”.

  49. Davec

    Two words: Martian Graboids!

  50. J5

    @21. Freerefill

    That’s a good point! There’s a very good chance we’re looking at a mound of sand inside the tube, aren’t we? I wonder how deep it really is!

  51. Chris A.

    @Chris (#39):
    “Falling only 25 ft on Earth is nothing? OK go walk blindfolded on your roof and let me know how that goes!”

    I didn’t say it was nothing! I said it was “survivable but uncomfortable” (mitigated somewhat by the fact that you’d be landing on soft sand). Ask the military guys who rappel comparable distances at near-free-fall speeds from helicopters.

  52. … but you couldn’t pay me enough to go inside one of those. I have no desire to be slowly digested over ten thousand years.

    So .. being digested by the Sarlacc *increases* your lifespan by many orders of manitude from being about 80 odd years to living to ten thousand years old? Meh, I could live with that. (Although the “in great pain” bit I could do without!) ;-)

    If that’s a punishment it’s an odd one. Not to mention the biological improbabilities. I’ve heard of slow metabolisms but ..

    Still a classic scene and battle though. :-)

    (Click on my name for the memories – the first movie I ever remember watching.)

    If this cave isn’t already known as “the Martian sarlacc” it will be now. ;-)

    PS. If you hadn’t said that was on Mars I never would have guessed. Looks so much more like ice or salt than sand there.

  53. Mircea

    That’s the lizzard eye, from Rango :)

  54. Andrew

    That would make a great album cover! Oh, if only they still existed…

  55. Richard Smith

    @alfaniner (#46): The 1953 version, of course? Not Tobe Hooper’s 1986 version with those giant rubber meatball martians and their penny-powered weapons. (Not that the…um…head martian in the original was exactly awesome FX…) The public school I went to had a big sand pit in the playground, and I’d always feel a bit leery of it after watching that (1953) movie.

  56. Don’t these people know anything about digital image processing? I think not! The cone is made of worked METAL! It’s not sand at all! Anybody can see THAT who correctly processes the photo!
    http://www.freecommonlaw.us/mars2/MaSaucer.png

  57. Dr Medford
  58. Nigel Depledge

    The BA said:

    they’d be protected from sand storms, temperature swings, and solar radiation (which is worse than for us on Earth because Mars doesn’t have a strong magnetic field to protect it).

    Aw, c’mon, BA, that’s only half the picture!

    Our magnetic field protects us from the solar wind, but it’s our atmosphere that protects us from harmful UV insolation. Mars has neither a magnetic field nor a thick enough atmosphere to protect its surface from harmful radiation (whether particulate or EM).

  59. Nigel Depledge

    Chris A (52) said:

    I didn’t say it was nothing! I said it was “survivable but uncomfortable” (mitigated somewhat by the fact that you’d be landing on soft sand). Ask the military guys who rappel comparable distances at near-free-fall speeds from helicopters.

    Actually, a 25′ fall onto a hard surface is likely to result in a crippling injury. And sand is only good at dispersing the energy of impact up to a certain point (which is why they no longer use sand as a landing surface for the high-jump in athletics, but they still use it for the long-jump and the triple-jump).

    As for marines or paras who abseil from helicopters – they slow down at the bottom, shortly before reaching the ground.

  60. Donna Beard

    It looks to me that this is a hill, and the sand is falling away from the outside.

  61. Who cares how it formed…..How many star fighters can you fit in there? ;-)

  62. Wzrd1

    One other possibility that wasn’t discussed by BS, subsurface water flows could ALSO generate such a chamber.
    As could highly saline water, which dissolved the stone beneath the surface, forming caverns, which can have a roof failure, generating a sinkhole.
    Well, I’ve got the coordinates for that location. When I get my ship’s engines fixed, I’ll pop on down and look it all over for you nice folks. ;)

  63. featheredfrog

    Man those Martian Ant Lions must be huge! So how big are the martian ants?

  64. Brent

    This image is awesome.

    The comments following, caused my love of nerds to increase ten fold.

  65. Chris Winter

    “Any chance this is an impact crater over a lava tube with a collapsed roof?”

    It’s either that, or the lair of the dreaded bat-rat-spider. ;-)

    (cf. The Angry Red Planet)

  66. Uncle B

    Meanwhile, back here on earth where we live, “Unemployables” lines lenghten in America, Capital flees to Asia and the American infrastructure crumbles. Even China has safer cheaper pebble bed gas reactors, safer, cheaper Thorium fueled CANDU reactors, and will soon have Thorium fueled LFTR reactors. Chinese folk ride on electric bullet trains for modest ticket prices, live in great planned cities just recently built, expect full employment at Ford Motor Company factories – all Ultra Modern designed to be run by 98 pound Asian women, yet make the same product the U.A.W. did here, but for much, much cheaper, and astoundingly faster, to computer controlled and much tighter specs! GM even put a Chinese engine in light trucks sold in U.S. already.
    Yes, Americans are freely given fantastic pictures of the Universe, close-up details of Mars, even geological information and actual rocks from the Moon – but just what is the point of all this?
    Stoned on cheap drugs from Mexico and Columbia, soaked in Fluoride salts, drunken, poorly fed on fatty high corn sugar diets, and totally mesmerised by the Great corprate, Capitalist whor’s propaganda machine into obsessive consumerism, the fatted calves await for the Asian sacraficaial alter to arrive. Nothing from the skys will save them, nothing found on Mars will change earthly facts, America is not only broke, but deeply in debt – the largest debtor nation in the history of mankind – and mostly to the growing Asian hoards.
    Time is soon, the holocaust will arrive, the U.S. dollar will fial, there will be no mercy, no oil, no electricity, no food, America ! The capital is fleeing with the corporatists! You are so doomed!

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