Inner Channels in Martian Valleys: First Results from High Resolution Stereo Camera (HRSC) images

Abstract

Inner channels are the best evidence found of sustained fluid flow on Mars. The first inner channels have been observed in high-resolution MOC imagery in Nanedi and Nirgal Vallis. These channels have widths between 50 m to 150 m, but only small parts of the channel lengths of a few kilometer are covered by MOC. New inner channels have been obseserved in the image data of the High Resolution Stereo Camera (HRSC) onbord of Mars Express in Libya Montes, south of Isidis Planitia (0°-5°N and 82°E and 90°E). The great advantage of the HRSC-images is the large covering of the surface in one image (50 km x ~1500 km) in combination with a high resolution of 12 m/pxl, and the additional stereo imaging. This gives us the opportunity to retrack inner channels over a long distance. The channels are located in kilometer broad valley networks and have an average width of about 150 m with observable lengths up to 130 km. They show meandering patterns, are sometimes interrupted and age relations can be seen by superimposed craters.