Title: Valles Marineris Hemisphere, Mars

Source: U.S. Geological Survey, Flagstaff, Arizona

Information: Mosaic of the Valles Marineris Hemisphere of Mars projected into point perspective, a view similar to that which one would see from a spacecraft. The distance is 2,500 kilometers from the surface of the planet, with the scale being 0.6 kilometers per pixel. The mosaic is composed of 102 Viking Orbiter images of Mars. The center of the scene (latitude -8, longitude 78) shows the entire Valles Marineris canyon system, more than 2,000 kilometers long and up to 8 kilometers deep, extending from Noctis Labyrinthus, the arc-like system of graben to the west, to the chaotic terrain in the east. Many huge, ancient river channels begin from the chaotic terrain and from north-central canyons running north. Many of the channels flowed into a basin called Acidalia Planitia, which is the dark area in the extreme north of this picture. The three Tharsis volcanoes (dark red spots), each about 25 kilometers high, are visible to the west. South of Valles Marineris is very ancient terrain covered by many impact craters.