ChatGPT’s math says that a picogram at 0.999c delivers about the energy of a strong human punch. Aside from issues of metal fatigue that wouldn’t seem like the

ChatGPT’s math says that a picogram at 0.999c delivers about the energy of a strong human punch. Aside from issues of metal fatigue that wouldn’t seem like the thing to be most concerned with regardless of distance - the effect to me would seem closer to space rain (assuming you could dissipate the heat which seems like the bigger problem). Dust is a concern but again the typical dust particle size would be about the power of a gun shot of a small caliber rifle. A problem to deal with but a rarer event still. Of course another challenge would be larger dust particles which while improbable are still possible which largely rules out humans in these craft. But that goes without saying since the acceleration to get to that speed would be unlikely something humans could withstand anyway.