Click to enlarge. The landing site, picked from a list of four potential locations, was chosen for its mysterious martian polar layered terrain which scientists think may hold secrets about the climate and surface evolution of the planet. It is very different from the ground that covers the planet's mid-latitudes. Observed only at the poles, this rough undulating terrain is composed of layers of compressed dust, sand and water ice, said project scientist Richard Zurek, of NASA's Jet Propulsion Laboratory. He explained that the study of these layers could teach scientists about the history of martian climate much the same way tree rings reveal a great deal about climate and biology on Earth.
Scientists believe the surfaces of the martian north and south poles are relatively young.
These areas appear to be free of craters that pock the rest of the planet's surface. However, this does not mean they are smooth. The layered features seem to have been built up or eroded irregularly over hundreds of thousands, perhaps millions of years. The terrain varies dramatically throughout the polar regions. Some areas are rolling mounds of gently sloping hills, other regions are pocked with king-size potholes, while jagged hillocks and cliffs mark other places.