 Surface water ice is unstable at distances less than 5 AU from the Sun , so it is expected to sublime if it is exposed directly to solar radiation . Water ice can migrate from the deep layers of Ceres to the surface , but escapes in a very short time . As a result , it is difficult to detect water <unk> . Water escaping from polar regions of Ceres was possibly observed in the early 1990s but this has not been unambiguously demonstrated . It may be possible to detect escaping water from the surroundings of a fresh impact crater or from cracks in the subsurface layers of Ceres . <unk> observations by the <unk> spacecraft detected statistically significant amounts of hydroxide ions near Ceres ' north pole , which is a product of water vapor <unk> by ultraviolet solar radiation . 
