The European Space Agency’s Mars Express photographed the interesting upper part of the Reull Vallis region of Mars with its high-resolution stereo camera in 2012. The discovery of this ancient Mars river gives scientists a glimpse of the distant martian past. Scientists think that Reull Vallis formed when running water coursed through the red planet’s surface, carving a steep-sided channel through the Promethei Terra Highlands before running on towards the floor of the immense Hellas basin.
The ancient river system, which spans approximately 1500 km across the martian landscape, has numerous tributaries, one of which can be spotted making its way into the main valley towards the upper north side.
The ESA’s images show that the sides of Reull Vallis are sharp and steep, with parallel longitudinal features covering the floor of the channel itself. Scientists believe that these structures were caused by the passage of loose debris and ice during the “Amazonian” period due to glacial flow along the channel.
Scientists believe that liquid water carved the structure during the Hesperian period, which thought to have ended between 3.5 billion and 1.8 billion years ago.
This discovery comes as NASA’s Curiosity Mars rover recently captured an image with its Mastcam at “Yellowknife Bay” that offers some of the best evidence yet that Curiosity’s landing site was once a much warmer, wetter place. The image reveals white veins of minerals flowing through rocks on the floor of the red planet’s Gale Crater.