Martian 'Ghost Dunes' Could Preserve Signs of Ancient Life

Space.com | 7/12/2018 | Staff
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Could pits hold evidence of ancient Mars life? Researchers just found hundreds of crescent-shaped depressions on the surface of the Red Planet. These pits likely used to be sand dunes — each one the size of the U.S. Capitol building, according to researchers.

These 'ghost dunes' remain preserved because of their composition. Lava or sediments washed into the area with water and partially buried these dunes as it streamed around them. Like a mold, the buried part of the dune hardened over time. After wind blew the exposed sand away, the mold inside remained and showed where the full dune used to be.

Making - Ghost - Dune - Crescent-shaped - Dunes

The making of a ghost dune. a) Crescent-shaped barchan dunes form with the steep face away from the prevailing wind, seen with the black arrows. b) A slow-moving liquid such as lava or sediment in water flows around the dunes and buries them halfway before hardening into rock. c-e) Wind blows away the exposed sand and is directed inward to eventually mostly hollow out the pit. f) Some ancient sand may still lurk in the pits' deep crevices, protected from radiation.

"We know that dunes on Earth can support life, and dunes on Earth are very similar to dunes on Mars," lead author Mackenzie Day, a planetary geomorphologist (someone who studies planetary surface changes) at the University of Washington in Seattle, said in the statement.

Problem - Mars - Earth - Surface - Radiation

"One problem that Mars has that Earth doesn't is the surface radiation. If you are inside a dune, or at the bottom of a dune, and you are microbial life, the dune is protecting you from a lot of that radiation," Day added. "There is probably nothing living there now. But if there ever was anything on Mars, this is a better place than average to look."

Features like this aren't unique to Mars. The first ghost...
(Excerpt) Read more at: Space.com
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