Strange circular dunes on Mars spotted in these NASA photos

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The sand dunes were imaged as part of a program to see how frost melts on the Red Planet in late winter.

An image of almost perfectly circular sand dunes on Mars taken by the HiRISE camera.
An image of almost perfectly circular sand dunes on Mars taken by the HiRISE camera. (Image credit: NASA/JPL-Caltech/UArizona)

Planetary scientists have captured an image of near-perfectly circular sand dunes on the surface of Mars. While sand dunes across the Red Planet come in a wealth of shapes and sizes, such well-defined circles are unusual.

The slight asymmetry in the sand dunes shows their steep sides are orientated towards the south. The University of Arizona, which operates the High-Resolution Imaging Experiment (HiRise) camera used to take the image, pointed out in a statement that this indicates sands are blown southwards, though the Martian winds may be variable.

The image was taken on November 22, 2022, at a latitude of 42.505 degrees and a longitude of 67.076 degrees. It comes as part of a series of pictures taken by the HiRise camera that orbits Mars on the Mars Reconnaissance Orbiter (MRO) spacecraft.  

Related: Mars: Everything you need to know about the Red Planet

The collection of images is being used to monitor how frost recedes and melts on the Martian surface as the Red Planet reaches the end of its winter season. Illustrating this, while this image appears frost-free a similar image of the same sand dunes previously taken shows what they looked like while still covered in frost. 

The sand dune image was taken while the MRO was at an altitude of around 185 miles (300 kilometers) over the Martian surface. Each pixel in the image represents 25 centimeters (9.8 inches). 

This is just one of 60 sites on Mars being monitored by HiRise. The high-resolution camera has been orbiting the Red Planet since the MRO reached Mars in 2006 and began conducting the first dedicated survey of the planet's sand dunes.

Collecting repeated observations of sand dunes over the Martian year (lasting 687 Earth days) has allowed planetary scientists to monitor how fast the dunes move. This has revealed that sand dunes from the equator to the poles are advancing at rates of up to 3.3 feet (1 meter) per Martian year.

Circular sand dunes on the surface of Mars covered in frost.  (Image credit: NASA/JPL-Caltech/UArizona)

The camera has recorded a variety of Martian sand dunes with an impressive range of both sizes and shapes, revealing a great deal about weather conditions on the Red Planet. For example, while examining the Lyot Crater in the northern lowlands of Mars in 2010, HiRise imaged dune fields that indicated how local winds are channeled through the topology of this 146-mile-wide (236-kilometer) complex impact crater. 

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HiRise is also conducting ongoing research that looks at glacier-like formations across Mars and examines the crevasse-type fractures that punctuate their surfaces. By collecting repeated observations over time, the images can help scientists determine the kind of fracture mechanics that occur in so-called "viscous flow features" found at the bases of slopes on Mars. These deposits are believed to have once been rich in ice, but the source of this ice is thus far a mystery, according to NASA.

On December 21, 2010, the primary mission of the MRO ended five years and six months after its launch on August 12, 2005. This new image shows that even 12 years after the end of that mission the contribution to science made by the spacecraft and its HiRise camera is far from over. 

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Robert Lea
Robert Lea
Senior Writer

Robert Lea is a science journalist in the U.K. whose articles have been published in Physics World, New Scientist, Astronomy Magazine, All About Space, Newsweek and ZME Science. He also writes about science communication for Elsevier and the European Journal of Physics. Rob holds a bachelor of science degree in physics and astronomy from the U.K.’s Open University. Follow him on Twitter @sciencef1rst.

8 Comments Comment from the forums
  • rflulling
    Admin said:
    The sand dunes of Mars come in a wide range of shapes and s, but a new image shows sand dunes that are surprisingly near-perfect circles.

    Strange circular dunes on Mars spotted in these NASA photos : Read more
    While I generally respect that NASA knows what they're talking about. The images posted to this topic. I see no visual cues in the imagery that would indicate these are actually Dunes. In fact the exact opposite there's nothing there. They are holes. They don't appear to be very deep but they are holes. In fact there are several cues that would indicate this. Along the southwestern Edge you can see where the wind has blown up debris from inside the hole and formed a lip. You can also see where debris has rained down from actual Dunes that are present around the outer perimeter. And the differentiating color pattern of that material forms a trail. Like water running down the side of a rock.

    No there are several things that could be potential causes of this. It could be anything from a gas eruption under the surface. To potentially a life form. A worm for example. We have a number of animals here on Earth which produce very similar nests. But assuming it's not a living thing. It could also be an asteroid impact. Debris raining down from something. I think it's most likely to be gas erupting from under the surface. But whatever it is it is a hole.
    Reply
  • Chris Wood
    See https://en.wikipedia.org/wiki/Crater_illusion
    I'll go with what NASA says.
    Reply
  • jamestmallow
    rflulling said:
    While I generally respect that NASA knows what they're talking about. The images posted to this topic. I see no visual cues in the imagery that would indicate these are actually Dunes. In fact the exact opposite there's nothing there. They are holes. They don't appear to be very deep but they are holes. In fact there are several cues that would indicate this. Along the southwestern Edge you can see where the wind has blown up debris from inside the hole and formed a lip. You can also see where debris has rained down from actual Dunes that are present around the outer perimeter. And the differentiating color pattern of that material forms a trail. Like water running down the side of a rock.

    No there are several things that could be potential causes of this. It could be anything from a gas eruption under the surface. To potentially a life form. A worm for example. We have a number of animals here on Earth which produce very similar nests. But assuming it's not a living thing. It could also be an asteroid impact. Debris raining down from something. I think it's most likely to be gas erupting from under the surface. But whatever it is it is a hole.
    Hmmm, should I go with the planetary scientists or some random guy that thinks they are holes created by worms ?
    Reply
  • TruthB Told
    "There are more things in Heaven and Earth, Horatio, than are dreamt of in your philosophy." Hamlet Act 1 Scene 5
    Reply
  • Maxfester
    Admin said:
    The sand dunes of Mars come in a wide range of shapes and s, but a new image shows sand dunes that are surprisingly near-perfect circles.

    Strange circular dunes on Mars spotted in these NASA photos : Read more
    rflulling said:
    While I generally respect that NASA knows what they're talking about. The images posted to this topic. I see no visual cues in the imagery that would indicate these are actually Dunes. In fact the exact opposite there's nothing there. They are holes. They don't appear to be very deep but they are holes. In fact there are several cues that would indicate this. Along the southwestern Edge you can see where the wind has blown up debris from inside the hole and formed a lip. You can also see where debris has rained down from actual Dunes that are present around the outer perimeter. And the differentiating color pattern of that material forms a trail. Like water running down the side of a rock.

    No there are several things that could be potential causes of this. It could be anything from a gas eruption under the surface. To potentially a life form. A worm for example. We have a number of animals here on Earth which produce very similar nests. But assuming it's not a living thing. It could also be an asteroid impact. Debris raining down from something. I think it's most likely to be gas erupting from under the surface. But whatever it is it is a hole.
    I tend to agree, mostly, with your observations. My first thought was they were created by an upwelling of gases. Their proximity seems likely to be caused by a subterranean event of some kind.
    Reply
  • Unclear Engineer
    I tend to think of the word "dune" to mean a mound of particles (e.g., sand or dust) configured by wind.

    Using that definition, it seems strange that there would be nearly ciruclar dunes, especially given the interpretation that the same side of all of them show the effects of being "down-wind".

    So, I am wondering what physical process determines their consistent round shape?

    I can think of several natural processes for depressions (sink holes, meteor swam strike, etc.) but none that would create a batch of similar size and shape raised piles of particles. I would think that even volcanic vents spewing particles would probably have a more conical shape, rather than a flat dome shape.
    Reply
  • COLGeek
    Am I the only one thinking Martian mole men? :rolleyes:
    Reply
  • Think twice
    Unclear Engineer said:
    I tend to think of the word "dune" to mean a mound of particles (e.g., sand or dust) configured by wind.

    Using that definition, it seems strange that there would be nearly ciruclar dunes, especially given the interpretation that the same side of all of them show the effects of being "down-wind".

    So, I am wondering what physical process determines their consistent round shape?

    I can think of several natural processes for depressions (sink holes, meteor swam strike, etc.) but none that would create a batch of similar size and shape raised piles of particles. I would think that even volcanic vents spewing particles would probably have a more conical shape, rather than a flat dome shape.

    It also looks like there are vague hints of other circle shapes in the sand in between the main circular holes. I agree with the speculation of sink holes. Maybe a flow or movement of liquid underground is undermining the area and it’s slowly collapsing in holes. Can I link a photo of sinkholes?
    https://www.alamy.com/stock-photo-sinkholes-craigmore-maungati-near-timaru-south-canterbury-south-island-26066445.html
    Reply