Marks on Martian dunes may be tracks of dry-ice sleds

Marks on Martian dunes may be tracks of dry-ice sleds

NASA research indicates hunks of frozen carbon dioxide — dry ice — may glide down some Martian sand dunes on cushions of gas similar to miniature hovercraft, plowing furrows as they go. Researchers deduced this process could explain one enigmatic class of gullies seen on Martian sand dunes by examining images from NASA’s Mars Reconnaissance Orbiter (MRO) and performing experiments on sand dunes in Utah and California.

via ScienceDaily: Top Science News:

June 11, 2013 — NASA research indicates hunks of frozen carbon dioxide — dry ice — may glide down some Martian sand dunes on cushions of gas similar to miniature hovercraft, plowing furrows as they go.Researchers deduced this process could explain one enigmatic class of gullies seen on Martian sand dunes by examining images from NASA’s Mars Reconnaissance Orbiter (MRO) and performing experiments on sand dunes in Utah and California.”I have always dreamed of going to Mars,” said Serina Diniega, a planetary scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., and lead author of a report published online by the journal Icarus. “Now I dream of snowboarding down a Martian sand dune on a block of dry ice.”The hillside grooves on Mars, called linear gullies, show relatively constant width — up to a few yards, or meters, across — with raised banks or levees along the sides. Unlike gullies caused by water flows on Earth and possibly on Mars, they do not have aprons of debris at the downhill end of the gully. Instead, many have pits at the downhill end.”In debris flows, you have water carrying sediment downhill, and the material eroded from the top is carried to the bottom and deposited as a fan-shaped apron,” said Diniega. “In the linear gullies, you’re not transporting material. You’re carving out a groove, pushing material to the sides.”Images from MRO’s High Resolution Imaging Science Experiment (HiRISE) camera show sand dunes with linear gullies covered by carbon-dioxide frost during the Martian winter. The location of the linear gullies is on dunes that spend the Martian winter covered by carbon-dioxide frost. By comparing before-and-after images from different seasons, researchers determined that the grooves are formed during early spring. Some images have even caught bright objects in the gullies.Scientists theorize the bright objects are pieces of dry ice that have broken away from points higher on the slope. According to the new hypothesis, the pits could result from the blocks of dry ice completely sublimating away into carbon-dioxide gas after they have stopped traveling.”Linear gullies don’t look like gullies on Earth or other gullies on Mars, and this process wouldn’t happen on Earth,” said Diniega. …

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ScienceDaily: Top Science News

Marks on Martian dunes may be tracks of dry-ice sleds

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