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Comment by themodelplumber | Hacker News Reader

That's pretty fascinating. I admit I find it kind of strange that only the encryption key was affected in this way, i.e. that finding the newly-correct key proved a fix to the issues, as opposed to fixing one issue out of many linked to such an event.

It made me wonder--what are the odds of that? What is the relative exposure area of the encryption key compared to the rest of the onboard assets which could have been mangled?

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It probably wasn't the only thing affected. It's just flipping bits in encryption keys has much more dramatic and obvious effect than flipping other random bits in memory. Flip a bit in a raster image and you get one funny-looking pixel. Flip a bit in an AES key and you completely corrupt all the data handled by that key.

There's basically two things that happen with radiation in orbit.

* Ionizing dose weakens and disrupts crystalline structure. Wears things out / degrades their specs.

* Single, very high energy particles-- e.g. protons-- come in at high speed and change a voltage somewhere. This can have massively bad effects (e.g. it can, for non-radiation hardened parts, cause parts of the chip not meant to be a transistor to become one shorting power and ground-- this is a "single event latchup"). Or, it can affect the operation of one or a few adjacent bits of memory ("single event upset").

https://en.wikipedia.org/wiki/Single-event_upset

They probably had to find the key to get it to accept a command to restart and reread the key from ROM.

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