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MARTIAN HILLS
What forces shaped the complex layers in these Martian hills? One theory suggests the lower areas are made of older rock, like sedimentary rock on Earth. The ridges in this image, captured by the Mars Global Surveyor orbiter, are wide enough for a truck to drive on them. Three robotic explorers from Earth, arriving over the holidays, will attempt to unlock other scientific secrets of the red planet.
(12/24/03)