Planetary scientists have discovered more than 15,000 km of ancient riverbeds in Noachis Terra, a region in Mars’ southern highlands. This discovery suggests that Mars may once have been much wetter than previously thought. This HiRISE image shows a flat top, heavily eroded fluvial sinuous ridge on Mars; sand dunes can be seen migrating over the top of the fluvial sinuous ridge. Image credit: NASA / JPL / University of Arizona. The nature of the...
