The Mars Express spacecraft has returned stunning images of mountains and valleys that show signs of past volcanic activity, and suggest that glaciers once shaped the red planet’s surface. The pictures from Mars Express show the western end of the Valles Marineris canyon system, which stretches for about 4,000 kilometres close to the martian equator. In places, the main canyon is 10 kilometres deep, more than six times as deep as the Grand Canyon in Arizona. Mars Express’s High Resolution Stereo Camera (HRSC) has now photographed this area in more detail than ever before, picking out features as small as 50 metres across