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?
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").
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?