Sand Dunes Thawing on Mars
Credit: HiRISE, MRO, LPL (U. Arizona), NASA
Posted on 03/03/2008 2:20:32 PM PST by sig226
Explanation: What are these strange shapes on Mars? Defrosting sand dunes. As spring now dawns on the Northern Hemisphere of Mars, dunes of sand near the pole, as pictured above, are beginning to thaw. The carbon dioxide and water ice actually sublime in the thin atmosphere directly to gas. Thinner regions of ice typically defrost first revealing sand whose darkness soaks in sunlight and accelerates the thaw. The process might even involve sandy jets exploding through the thinning ice. By summer, spots will expand to encompass the entire dunes. The Martian North Pole is ringed by many similar fields of barchan sand dunes, whose strange, smooth arcs are shaped by persistent Martian winds.
Darn global warming. We need to ban SUVs on Mars.
OK, so how large are these dunes? I can’t get a reference scale pictured.
Arakis ping
No idea. I followed the Barchan dunes link, which gives a typical 34 degree upwind slope and 15 degree downwind slope for them on Earth. From there, some bored post grad could calculate the different angles for Mars, then determine the position of the sun, the relative sizes of dune and shadow, and compute the height of the dune.
I would suggest that he get a girlfriend first.
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