No ice AFAIK, it's the space station on the edge of an expanding area with alternate laws of physics (cellular automaton stuff) which they enter somehow and which is quite hostile to them.
I really liked the idea of how people are perfectly okay with their identity being only information, and sending themselves through space as radio waves etc.., I think it's similar to Diaspora in that.
But now I'm curious what sheets of ice you're talking about :P Just started reading book 1 of the Orthogonal trilogy, so far it's pretty cool.