Jean-Pierre Bibring is in charge of several programmes related to the exploration of Mars. He is a professor of physics at the University of Paris-Sud and an astrophysicist at the Institute of Space Astrophysics, at Orsay. Mars is visible with the naked eye and is doubtless the planet that has exercised the most fascination. Because of its colour Mars was associated with blood and symbolised the god of war. But over the last two centuries its status...