We have one of those pot racks which hang from the ceiling and has hooks for pots and pans. It's a small kitchen, so every so often my head hits one of the pots, resulting in a very unpredictable chain reaction of pot clanging against frying pan against saucepan, etc. etc. Gradually the interactions die out and the sounds fade away.
Turns out there could be the same sort of interactions in space, which possibility makes a hazard for ideas of NASA changing the course of an asteroid due to hit the earth. That's mentioned in this piece on NASA plans to practice such things. I applaud both the idea of practicing (see Harshaw rule) and the wisdom of anticipating interactions.