Argyre crater. Computer artwork of the surface of Mars, showing the Argyre impact basin (large area, centre) and the Galle crater, which lies on its eastern rim at upper right. The Argyre basin is approximately 1800 kilometres in diameter and is surrounded by mountains. It is the second largest impact basin on Mars. The Galle crater is about 230 kilometres wide and is often known as the 'smiley face' or 'happy face' crater because of the illusion of a smiley created by a semicircular mountain range and two smaller craters within the main crater.