Weird Crater on Mars is a Mystery

by Nancy Atkinson on August 27, 2010

Orcus Patera is an enigmatic elliptical depression. Credits: ESA/DLR/FU Berlin (G. Neukum

This is one of the strangest looking craters ever found on Mars, and this platypus-tail-shaped depression, called Orcus Patera, is an enigma. The term ‘patera’ is used for complex or irregularly shaped volcanic craters, but planetary scientists aren’t sure if this landform is volcanic in origin. Orcus Patera lies between the volcanoes of Elysium Mons and Olympus Mons, but its formation remains a mystery. This is the latest image of the object, taken by ESA’s Mars Express.

It could be an impact crater that originally was round, but then subsequently deformed by compressional forces. Or, it could have formed from two craters next to each where the adjoining rims eroded. However, the most likely explanation is that it was made in an oblique impact, when a small body struck the surface at a very shallow angle.

Relief image of Orcus Patera. Credit: ESA/DLR/FU Berlin (G. Neukum)

It is 380 km long by by 140 km wide, and has a rim that rises up to 1,800 meters above the surrounding plains, while the floor of the depression lies 400–600 m below the surroundings. The floor of the depression is unusually smooth.

The image above was created using a Digital Terrain Model (DTM) obtained from the High Resolution Stereo Camera on ESA’s Mars Express spacecraft. Elevation data from the DTM are color-coded: purple indicates the lowest-lying regions, and beige the higher elevations. The scale is in meters.

Source: ESA


Tagged as: craters, esa, Mars, Mars Express

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  • durga2112

    I’m not an expert by any means, but I wonder if this could be a crater chain, similar to Enki Catena on Ganymede, but caused by many different-sized objects? There’s obviously a lot more going on here, but to me it looks like there are a number of “partial craters” (for lack of a better word), especially along the left side of the feature.

    Again, not an expert, but I’m sure that’s already apparent since I really have no idea what I’m talking about. :)

  • Aqua

    How about an extremely close crater chain – meteor or volcanic? A sequential impact pattern fracturing the crust along a line? OR maybe an elongated object impacting flat to the length of the object? SPLAT! Whatever… sure is trick! But wouldn’t that be the color Blue indicating the lowest regions?

  • Aqua

    No.. I see it now. Purple it is!

  • Spencer

    I’ve spent a while looking at this photo. I don’t think it could be much of a crater, or two combined for that matter. If it were it would probably be much deeper, like some of the surrounding craters.

    Instead I’d like to say it’s a dry lakebed. Comparing it to an earthen dry lakebed, it looks quite feasible that it could have been a lake. Furthermore, it has those line-like impressions leading into it. I ask: rivers perhaps? Even though rivers on earth aren’t quite as straight, it still is a possibility. Last I see the darkened region within the impression that looks like dark dust that has been shifted by the wind. Looking at earthen dry lakebeds, they have can have patterns similar to this at their bottoms. Caused by what, I do not know, but it does seem like it would be rather out of place in crater.

    What do you think? Legitimate or definitely a crater?

  • DallenS

    Someone please verify that one of three things are wrong:
    1. The scale at the bottom of the first image
    2. The dimensions given in the article
    3. Or ME!

    I wanted to get some perspective as to how big this crater is so measured out the dimensions in Google Maps and found it to be about as wide as Pennsylvania and about half as tall if you go by the size given in the article. However when I measured the width of the crater using the scale it’s closer to 600km wide. That would add New Jersey and half of Long Island to the width – not a small difference!

    What gives? Am I the crazy one? :)

  • Jon Hanford

    A good view of this area is available using Google Earth at Mars or WWT Mars. The ESA release gives the coordinates as: 14deg N 177deg W. It’s easy to spot the graben mentioned in the article on the left side of the crater, stopping at the rim. In one case, a faint extension of a graben on the other side of the crater is visible! More images and info here: http://www.esa.int/SPECIALS/Mars_Express/SEMDV9BO3DG_1.html

  • Torbjorn Larsson OM

    I would like to see a simulation of a shallow impact reproducing that. Meanwhile a crater chain that have been heavily modified is much easier to buy.

  • Torbjorn Larsson OM

    “simulation – could be a scale model experiment. The point is that not only are shallow impacts giving ellipses few due to the very shallow angle required, it’s not at all given what track would result.

  • William928

    I tend to agree with SPENCER. A dry lakebed would make sense taking into account the relatively smooth floor, shape, and size and depth. The additional impact craters that exist inside the lakebed(yes, I’m calling it a lakebed) also support this conclusion.

  • Aqua

    On second thought… it looks like somebody came out of hyperdrive a little too close to the planet!

  • Don Alexander

    Absolut Mars 8-)

  • the_nthian

    I recommend you take a look at
    46°03’36″N 81°03’18″W
    It’s called the Sudbury Igneous Complex.
    http://ottawa-rasc.ca/wiki/images/d/d3/Odale-sudbury-00_shade_topo.jpg
    That’s the first thing I thought it looks like.

  • the_nthian

    I recommend you take a look at
    46°03’36″N 81°03’18″W on Earth.
    It’s called the Sudbury Igneous Complex.
    http://ottawa-rasc.ca/wiki/images/d/d3/Odale-sudbury-00_shade_topo.jpg
    That’s the first thing I thought it looks like.

  • agmartin

    I remember this, that’s where the saucer section of the enterprise D crashed.

  • Aqua
  • DrNothing

    I say it was an oblique impact crater that by chance occurred when there was a very large still partially molten area of lava from either Olympus or Elysian Mons. Could that not explain it’s shape as well as smoothness, as well as, perhaps the pattern of the high elevation northern and southern walls that are wider at the smaller southern end and taper off to the east, and are non-existent on the southern and eastern most rims?

  • Spoodle58

    I would agree with durga2112 & Aqua, in saying a crater chain, I can see possibly 6 craters and there could be more. Looks like the impactors hit at an angle and like what Nancy says in the article above but instead of one oblique impact their appears to be more.

    Those who say a lakebed have to into account the relief map also, notice how the edge of the depression rises up out of the surrounding plains, this is more associated with crater formation, it may be possible that a lake existed there after the formation of the feature.

    If we take an object like comet shomaker levy 9 that broke into some 21 fragments or the crater chain Enki Catena on Ganymede as well as dozens more of these features throughout the solar system we have a way of explaining the crater chain formation, take also into account the erosion and deposition qualities that Mars possesses, (dust storms etc) and we have a explanation as to how the crater floors have a relatively even surface fill.

    A extremely interesting feature and a great place to send a geologist, human preferably :) .

  • HeadAroundU

    God, I love the 2nd pic. It’s punk plastic Andy Warhol.

  • Emilio

    We should send Radar Satellite to Mars so that we can see the topography under the surface fill.

  • http://www.cheapastro.com Steve Nerlich

    Any skier or snow boarder could pick this immediately. It’s a face plant.

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