When I was peripherally working on some HPC stuff, there was a comment by one of the hardware guys that it mattered which national lab you were building the supercomputer for, because the guys at high altitude like Los Alamos get a lot more bitflips than someone closer to sea-level like Argonne. Although that said, for an exascale supercomputer, the mean time between uncorrected bit flip somewhere in the machine is on the order of a few hours, which means that large supercomputer-scale workloads should actually expect to hit a bit flip in their computation.

Cosmic rays can probably be resolved with some parity bits and redundancy. Especially since these don't have to be located way up in geosynch, lower orbits get you more magnetosphere protection.

Not that it isn't a problem, but I think heat dissipation will have the edge.

I mean, LLMs are already a pile of stochastic output .. maybe that just adds to the fun? /s