This was something I just saw and not 100% sure of the circumstance, but it seemed like one of my bunker doors broke, maybe without even dropping its materials, right as it finished closing. The meteor might have actually been inside the door, I'm not sure. The door is at the very top of the asteroid.
This is also on the minibase map, so the door is right next to neutronium on its left
close bunker door, have a meteor hit it in just the right way