False-colour representation of the topography of the two river valleys in the Libya Montes region
False-colour representation of the topography of the two river valleys in the Libya Montes region
Data acquired by the nadir channel of HRSC, which is aligned perpendicular to the surface of Mars, and the stereo channels can be used to generate Digital Terrain Models of the Martian surface with an accuracy of up to ten metres per pixel. These colour-coded representations clearly show the absolute heights above a reference surface, an Areoid (derived from the Greek word for Mars, Ares). Blue means low-lying; white indicates high altitude. North is on the right of the image. The water episodically flowing through the highlands has excavated valleys into the landscape with a depth of several hundred metres. There is a difference in altitude of about 3000 metres between the start of the valleys at the edge of an extremely weathered crater, which was presumably filled by a lake (on the left side of the image), and the plains around 150 kilometres further north on the right side of the image. This is around a thousand metres more than between the source of the River Inn near St. Moritz and the point where it flows into the Danube near Passau, but only about a third of that river’s length, so the average gradient of this river on Mars was three times as steep as a typical Alpine river.