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Extensive mega-ripple activity in the Arctic region of Mars

2 Driven by summer katabatic winds modulated by cap retreat, it produces the highest known sand flux on the planet. The width of the view is about 1km. Credits: HiRISE Digital Elevation Model DTEPC_036176_2640_035926_2640_A01 and Color Ortho Image ESP_053345_2640. HiRISE data: NASA / JPL / University of Arizona “width =” 600 “height =” 270 “”/>

“Mega Ripple” is a bed foam with a clear wind that occurs on the surface of the Earth and Mars. Here, using the data returned from the High Resolution Imaging Science Experiment (HiRISE), this perspective view shows the megaripple in the lower center adjacent to the Arctic dunes.These Arctic megaripples and dunes are driven by seasonal CO-modulated summer katabatic winds, producing the highest known sand flux on Earth.2 Cap retreat. The width of the view is about 1km. Credits: HiRISE Digital Elevation Model DTEPC_036176_2640_035926_2640_A01 and Color Ortho Image ESP_053345_2640. HiRISE data: NASA / JPL / University of Arizona

Megaripple, a medium-sized bed foam caused by the action of wind, has been extensively studied and, with a few exceptions, is believed to be an inert relic for most of the past climate. A new paper by research scientist Matthew Hoinatsuki of the Institute of Planetary Sciences shows that abundant megaripple populations have been identified throughout the Arctic region of Mars and are moving with sand dunes and ripples.


Martian Mega Ripple is about 1-2 meters high and 5-40 meters apart. The size is between ripples about 40 cm high and 1-5 meters apart and dunes hundreds of meters high and 100 meters apart. Up to 300 meters. Although the speed of movement of Mega Ripple is relatively slow (average 0.13 meters per year on Earth), some of the nearby ripples have been found to move an average of 9.6 meters per year in just 22 days of summer in the Northern Hemisphere. I did. This is an unprecedented speed on Mars. These high sand movements help explain the activity of Mega Ripple.

“We investigated the dynamic activity of polar bedforms using repetitive HiRISE images taken over a long period of 6 years on Mars or 13 years on Earth. The thin atmosphere of Mars mobilizes coarse-grained megaripples. And it turns out that these can overturn the previous notion of static relic terrain. From past climates. Megaripple across the Arctic Sand Sea, the largest collection of Martian dunes fields. And mapped the adjacent bed form. ” Journal of Geophysical Research: Planets..

Extensive mega-ripple activity in the Arctic region of Mars

Polar bed foam site with active mega ripple as seen on HiRISE. The approximate transport direction is at the bottom left and the inset is 100 meters wide.Credits: HiRISE Data: NASA / JPL / University of Arizona

Part of the uncertainty in studying the polar terrain of the planet is the long, cold polar winters that eventually cover the area with carbon dioxide and water ice. For wind-driven bed foams such as Mega Ripple, that means they can’t move for almost half a year. “But the late spring and summer breeze from the polar cap looks more than compensating for these other periods of inactivity,” Choinakki said.

“We found that Mega Ripple is spread throughout the region and is moving at a relatively high speed compared to other parts of Mars at low latitudes. This enhanced activity is driven by the summer. It may be related to the large flow of sand found in the adjacent dunes. Seasonal winds when polar ice is sublimating. This is because much of the surface of Mars is ancient or static. Not only does it support the idea of ​​being actively modified, “said Chojnacki. “In contrast, other megaripples appear to be stable, which may be the result of grain boundary ice in low wind regions.”


Hidden order of windswept sand


For more information:
Matthew Chojnacki et al, Extensive Mega Ripple Activity Across the Arctic Erg on Mars, Journal of Geophysical Research: Planets (2021). DOI: 10.1029 / 2021JE006970

Quote: Extensive megaripple activity found in the Arctic region of Mars (January 12, 2022) is from https://phys.org/news/2022-01-widespread-megaripple-martian-north-pole.html to 2022 Obtained on January 12, 2014

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Extensive mega-ripple activity in the Arctic region of Mars

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