Re: "Accurate [..] predictions are essential for understanding the hazard they pose to spacecraft"
Near space is very much cluttered but the problem is the size of the debris which can be a fleck of paint or less than a fraction of a millimetre. And no, satellites. do not "autonomously move themselves to avoid collisions" especially if the debris can not be seen or detected. Read about the RemoveDEBRIS project, which attempts to deflect debris into entering our atmosphere, and thus burning up.