Planetary researchers have mapped and characterized ancient sand dune fields in the canyons of Valles Marineris on Mars. Their discovery offers new insights on past climatic conditions on the Red Planet. This oblique color view from the HiRISE instrument onboard NASA’s Mars Reconnaissance Orbiter shows a lithified field of sand dunes within Melas Chasma, Valles Marineris. The large degree of preserved morphology for many of these paleodunes reveals...