On Mars, Dry Ice 'Smoke' Carves Up Sand Dunes: Page 2

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NASA's Mars Reconnaissance Orbiter snapped this series of pictures of sand dunes in the north polar region of Mars, showing how dark sand rises to the top as spring progresses (from left to right) and a surface layer of carbon dioxide ice crack.
NASA/JPL-Caltech/Univ. of Arizona

The escaping gas also carries sand, which forms dark streaks as it spills across the dry ice covering the dune. These dark fans disappear as the seasonal ice evaporates, and Martian winds erase most of the newly formed grooves before the next winter and springtime roll around.

The grooves are smaller versions of the "gullies" MRO has spotted on other, steeper Martian dunes, which were apparently formed in a similar way, researchers said. And similar processes have been observed near the Red Planet's south pole.

"It is a challenge to catch when and how those changes happen, they are so fast," Ganna Portyankina of the University of Bern in Switzerland, lead author of another one of the studies, said in a statement. "That's why only now we start to see the bigger picture that both hemispheres actually tell us similar stories."

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The three new studies, which appear in the journal Icarus, were based on observations made by MRO over three Martian years, or about six Earth years. The papers document a variety of seasonal changes on Mars, including the dune grooves and the distribution of water frost, which is blown around by springtime winds.

This article originally appeared on Space.com.

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