bild

Water on Mars. Computer artwork looking south over water around the snow-covered Apollinaris Patera volcano on Mars 3.5 billion years ago. The volcano is about 5 kilometres high and the caldera (centre crater) is around 80 kilometres across. The Gusev Crater (upper centre) has an outlet to the Ma'adim Vallis (Ma'adim Valley) behind it. Eroded features seen on Mars today, suggest that water once flowed there. Mars is now a desert world. The water was ultimately lost due to the thin Martian atmosphere and weak gravity. The topography was drawn with Terragen software, using data from the laser altimeter on the Mars Global Surveyor probe. (KEYSTONE/SCIENCE PHOTO LIBRARY/KEES VEENENBOS)