Sand structures, intermediate in size, that are not quite like anything on Earth, are among the mountainous dunes and small undulating ripples of Mars.
The physics of how ripples and dunes arise on Earth are incompatible with the physics of how the sand on Mars forms.
The results suggest that scholars may be able to reconstruct the atmospheric history of Mars using fossils. There is a mathematical relationship between atmospheric density and the size of wind blown ripples and dunes.
"This is important because it is thought that Mars used to have a thicker atmosphere in the past, perhaps sustaining Earth-like surface conditions," Laptre said. We don't really know why it lost most of it.
Air flow or torpedoes?
dunes that extend for miles to tiny ridges barely high enough to hide a crab are just some of the shapes and sizes of sand grains on Earth and Mars. The crests of the ripples are usually a few inches apart. They're found in deserts, on beaches, and in sandstone. Impact ripples are caused by wind blowing grains into sand mounds.
Images of similar patterns on the surface of Mars were returned in 2015. In addition to giant dunes, the images showed smaller waves at two different scales: Some were close to the size of impact ripples familiar in similarly sized grains on Earth; others were about 10 times bigger, yet still smaller than dunes.
Scientists have been puzzled by how these two different scales came together on Mars. The middle-sized structures are caused by the constant growth of impact ripples on Mars. Scientists had observed an unexplained absence of ripples with crests between 8 and 30 inches apart.
According to Laptre and other scientists, the shapes could be a result of the same instability that causes wind blown dunes in deserts and similar undulating mounds in sandy riverbeds.
The size of larger Martian ripples and dunes, and ripples that form underwater on our own planet, could all be controlled by the same shift, or anomalies, in the flow of air or water, according to researchers. This shift is caused by interplay among global atmospheric properties like density and local factors.
Scientists had only been able to theorize about the anomalies from tightly controlled experiments. It hadn't been seen in the dunes.
The Dune is recognized.
Together with lead author Lior Rubanenko, Laptre and colleagues set out to test these theories with data from Mars. This is the first time that scientists have used real data from the red planet to test a theory that says the size of Mars' smallest dunes should decrease where the air is thicker.
A computer vision model developed to pick out different types of objects from a background was used to pick out three people, a bus, and two cars in a photo. In order to train the model, the team manually labeled the dunes in a small subset of images.
The authors looked at the data along with the calculations of atmospheric density. The waves are not impact ripples at all. The structures on Mars are more like miniature dunes that stop growing at a certain point because of the thin, turbulent atmosphere close to the surface.
According to Rubanenko, impact ripples on Mars are the same size as they are on Earth. The mechanism that creates impact ripples has more to do with sand transport than it does with the atmosphere.
Laptre said that the size of ripples in rocks can be used to reconstruct the history of Mars.
The morphometrics of barchan dunes reveal a distinct ripple-formation regime on Mars. There is a DOI titled: 10.1038/s41467-.
Journal information: Nature Communications
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