During its historic close encounter with Phoebe in June 2004, the Cassini spacecraft captured a series of high-resolution images of the small moon, six of which have been put together to create this mosaic. The image shows evidence for the view that Phoebe may be an ice-rich body coated with a thin layer of dark material. Small bright craters in the image are probably fairly young features. This phenomenon has been observed on other icy satellites, such as Ganymede at Jupiter. When impactors slammed into the surface of Phoebe, the collisions excavated fresh, bright material -- probably ice -- under the surface layer. An accurate determination of Phoebe's density will help Cassini mission scientists understand how much of the little moon is composed of ices. (© AP Images)