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Martian North-Pole Ice Cap
This image of the Martian north polar ice cap shows layers of water ice and dust. Here we see cliffs which are almost 2 kilometers high, and the dark material in the caldera-like structures and dune fields could be volcanic ash. The image, digitally reconstructed into a perspective view, was taken by the High Resolution Stereo Camera on board the ESA's robotic Mars Express spacecraft currently orbiting Mars.