Jos joku vielä epäili onko Marsissa vettä... "This white patch is present all year round, as the temperature and pressure conditions do not favour the sublimation of water ice. It cannot be frozen carbon dioxide since carbon dioxide ice had already disappeared from the north polar cap at the time the image was taken (late summer in the Martian northern hemisphere). "

Water ice in crater at Martian north pole (via Boing Boing)