Stereo topography of the south polar region of Mars: Volatile inventory and Mars Polar Lander landing site

Viking stereo images and topographic maps reveal that the south polar layer ed deposits of Mars are topographically complex and morphologically distinc t from the north polar layered deposits. The dominant feature is a 500-km-w ide topographic dome that rises 3 km above the surrounding plains. This dom e underlies the residual ice cap but is at least 50% larger in area. Erosio nal scarps and terraces indicate that this dome was once more extensive and has undergone erosional retreat. Adjacent to the dome, layered deposits fo rm a vast plateau 1-1.5 km high extending similar to 1000 km beyond and to one side of the residual south polar cap. This plateau is relatively flat a t kilometer scales, although it is cut in places by troughs and depressions , which have locally steep scarps up to 2 km high and sloping up to roughly 10 degrees. Contiguously flat kilometer-scale regions the size of the Mars Polar Lander (MPL) landing ellipse are present. These are in the form of p lateaus 100-300 km wide and 1-2 km high. One of the largest of these platea us tias been proposed as a landing site for the Mars Polar Lander (MPL). Th e volume associated with the south polar layered deposits may be comparable to those of the layered deposits at the north pole. Although this doubles the current probable inventory of surface ice on Mars, it still fails far s hort of accounting for the inferred volume of water on Mars in the past.