[Buttons840]

Are you sure? My KSP intuition tells me this is wrong.

Orbits are circular and constant (accurate enough for my argument). An impact might cause some debris to go up, but when the debris that went up comes back around to the same spot in its orbit, it will again be going up. Well, extrapolate that backward a bit and you realize the debris that is going up was inside the atmosphere moments before.

In other words, if an instant impulse causes an orbit to have a higher apoapsis, it must also lower its periapsis. Which means the piece will go deeper into the atmosphere, and you don't come back from deep in the atmosphere.