Images taken by Europe's Mars Express spacecraft show a crater on the Red Planet that looks like a "happy face". Crater Galle contains parallel gullies on its southern rim, a possible sign of liquid water running on Mars' surface. Its interior has also been shaped by the action of wind and shows signs of "dust devil" tracks, which have removed the bright surface coating of dust. A US space agency (Nasa) orbiter has also sent back its first colour image after arriving at Mars on 11 March. The "face" in the European images was first pointed out in photos taken...