[tutfbhuf]

If a barrier can stop a .50 cal BMG, then it should be sufficient to stop space debris. 20-30 cm of concrete should be enough.

[ben_w]

I have no idea how fast it was going when it hit, but as it is more than 10x the mass of a 50 cal, I wouldn't rely on the assumption that protection from the latter is also protection from the former.