Thank you, others pointed this out too. Proves that "celestial mechanics" is trickier than I thought. I guess if a collision is messy enough, there would be se

Thank you, others pointed this out too. Proves that "celestial mechanics" is trickier than I thought. I guess if a collision is messy enough, there would be secondary collisions between debris pieces, and it sounds like these in principle can push some junk into higher orbits. But I think the probability is really low; this should not be a concern.