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Though Mars is the Red Planet, false-color images can help us learn about its weather and geology. This image shows a variety of wind-related features on the Red Planet near the center of Gamboa Crater. Larger sand dunes form sinuous crests and individual domes.
There are tiny ripples on the tops of the dunes, only several feet from crest-to-crest. These merge into larger mega-ripples about 30 feet apart that radiate outward from the dunes. The larger, brighter formations that are roughly parallel are called “Transverse Aeolian Ridges” (TAR). These TAR are covered with very coarse sand.
The mega-ripples appear blue-green on one side of an enhanced color cutout while the TAR appear brighter blue on the other. This could be because the TAR are actively moving under the force of the wind, clearing away darker dust and making them brighter. All of these different features can indicate which way the wind was blowing when they formed. Being able to study such variety so close together allows us to see their relationships and compare and contrast features to examine what they are made of and how they formed.
Image Credit: NASA/JPL-Caltech/University of Arizona
Last Updated: Jul 25, 2022
Editor: Yvette Smith
Well, Martians were not little green, but little blue men.
Small dunes are likely made by martian wind, the large one are unlikely to survive millions of years to be made by some kind of water flow.
Martian atmosphere density is slightly less than 1%, while it’s gravity on surface is 30% of the Earths, so I would think, it would take a very persistent and unusually strong wind to create smaller dunes. Length of day and obliquity are near-same as Earths but year and therefore seasons are nearly two times longer so wind could persist as long as one Earth’s year, sufficient time to build, break and re-orientate smaller dunes.
Big puzzle are big ripples, I would speculate (due to low gravity, hence low density of sand packing) they could be caused by small ground movements or vibrations, due to prolong heating and cooling (year ~690 days) or more likely liquefaction from minor quakes in the martian lithosphere.
Liquefaction
https://www.britannica.com/science/soil-liquefaction
Vuk, I share your thoughts about liquefaction. Here is the upper surface of a sandstone bed with similarly shaped rounded ridges and depressions that I think were produced by earthquakes. The scale is vastly different: these ridges and depressions are just a few millimeters wide.
When I enlarged the image, it appears there is ‘direction’ on the large dunes. Steeper slopes all on the same side and lower gradient slopes on the opposite.
I would speculate the dominate wind direction is near the lower left corner of the image passing out of the top of the image right of center
Ripples, yeah. But I’m finding the depressions separating the rippled areas really interesting. The pattern seems really odd to me, but then I’m not a geologist who might know why those pockets form that pattern.
Just being pedantic, but the study of Martian landscapes and planetary structures are Areologic not Geologic.
I was looking for an analogue here on Earth, but I also didn’t know that.
So, thanks for giving me a new term, RS. 👍
I see a picture of an example of liquification in a comment to Vuk just above. It does look similar to the image for the article.
This digital scene appears to be far more complicated than just ripples produced by wind, as the ripples swirl through various orientations and even cross-cut each other. If I saw this image from a similar setting here on our planet I might think it rained, producing rill marks, on top of wind-scoured sand dunes. Nice resolution, showing great technology in acquiring the data and transmitting it back here.
As an average Joe, it looks like the white, light purple & light yellow areas on
top of the flat ridges are exposed rock, which actually determines the shape
of the larger, sand covered ridges. The rocks determine the shape of the
larger ridges, including occasional gouges. Some of the sand ridge lines
look like they’re filling gaps between separate rock islands that project out of the surface. The very fine lines look like finger prints. (all one big SWAG)
I agree that the linear blue features look more like rills than dunes.
Mars Guy: https://www.youtube.com/c/MarsGuy
frames by Rado: https://www.youtube.com/c/framesbyrado
Fantastic photos from the rovers.
Very lovely.
Now tell us why that crater is not full of water.
Mars is very cold. I doubt very much if we’ll find any liquids at all. While water ice might be found, the best we can hope for is “dry ice” aka frozen CO2.
Don’t pack your beach towels. But dune surfing might be available. Although, the much lower gravity might make the ride rather slow.
Ridiculous.
Misinformation.
With NO scale there is NO possibility to venture an interpretation.
From the left to the right margin of the picture, how many km, meters, cm, mm, … ?
Then, what is the difference between this picture and some abstract expressionist painting?
Yes, a scale might have been nice. If you would care to perform some analysis, contact NASA. If you merely wish to vent your ignorance you are performing nicely.
From the article:
This is a HiRISE image, although that isn’t mentioned in this terse article. A quick online search provides the information that the HiRISE instrument has a resolution of 12″ per pixel.
False color images are helpful when they can be used to differentiate otherwise invisible to the naked eye features.
False color images, as this one is, should always be clearly labeled — unlike hundreds of NASA images of stars and nebulae.
HiRISE has three bands: Blue-green, Red, and Near-IR. There is no mention of how those three bands are mapped to the RGB channels of the output display device. That is important information because it would tell us which bands are most reflective for the various features. That might help some of us geologists to speculate on what we are seeing.
Just beautiful. Now I won’t need to travel there to see. I did apply to be a Canadian physician astronaut some years back but somehow that didn’t come to pass. My wife, who had been measuring my wardrobe space and wondering how long I might be away, suggested they may have got wind of my year of birth. The saddest part is that the merriment my application afforded my children was quickly extinguished once they realized I would need to stay in my day job for a while longer.
Also you need Covid vaccination as they won’t let you go not Mars without it