Panels c and d are close-ups of the pits, showing the crescent shapes of barchan dunes. But if there ever was anything on Mars, this is a better place than average to look.'ĭune cast pits (panel b) found at Noctis Labyrinthus, west of Valles Marineris, indicated as the black star in panel a. 'There is probably nothing living there now. 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. 'One problem that Mars has that Earth doesn't is the surface 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. (Image credit: Mackenzie Day/David Catling/AGU)

f) Some ancient sand may still lurk in the pits' deep crevices, protected from radiation. c-e) Wind blows away the exposed sand and is directed inward to eventually mostly hollow out the pit.

b) A slow-moving liquid such as lava or sediment in water flows around the dunes and buries them halfway before hardening into rock. a) Crescent-shaped barchan dunes form with the steep face away from the prevailing wind, seen with the black arrows.

Face of mars ghost