[anotheryou]

The US monitor a lot of the tiny chunks flying around and predicts where they go. Worst case the satellite has to flight an evasive maneuver. Usually it's a false alarm, but we can't measure well enough to make perfect predictions.

I think they do it with radar right now and the future cloud would be lasers, especially for more accurate measures of things already flagged as dangerous. I might mix things up here though.