The discovery, based on research in Alaska, opens a window on processes at play early in Mars' history, when it hosted an environment that could have harbored microbial life.
Shifting dunes on Mars, especially those near the planet's north pole, may harbor layers of liquid water not far beneath their ice-encrusted surfaces.
That is the implication of studies of sand dunes in Alaska's Kobuk Valley National Park, some 380 miles northwest of Fairbanks. There, above the Arctic Circle, researchers using the dunes as stand-ins for dunes on Mars have found evidence for liquid water trapped between the dunes' icy winter coat and subsurface layers of ice or freeze-dried silt that form a temporary, cement-like barrier that prevents the water from percolating deeper into the dune.
The water remains liquid because it exists in an environment of temperature and pressure that allows liquid water, ice, and water vapor to exist side by side.
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