> easily afford a kilometer or two of shielding. Since even the most energetic
> secondary radiation isn't going to penetrate more than a few hundred meters of
> solid matter, that means that impacting nanoprobes are no threat at all.
I don't know. A relativistic piece of matter is a lot like radiation. Damn dense radiation. If it's fast enough it may tunnel through quite deep before it gets down slow enough to unleash its havoc.
Has anyone modeled this?