Re: [amsat-bb] AO-40 Telemetry Archive Updated

[Bruce Bostwick <lihan@xxxxxxxxxxxxxxxxxx>]

>[...] Something really nasty happened for electronics
>to fail after working for days.  Karl's note, from the
>most conservative person I know in some ways,
>states  that he did not trust to have the 2 meter
>transmitter turned on yet.  I think that is probably
>totally due to the fact that only the S2 would come
>on.  These are widely separated sensors that we appear
>to have failed.  They are spread all over the spacecraft.

One possibility is that an energetic cosmic ray particle hit part of 
the outer frame of the spacecraft and the shower from that happened 
to hit a whole bunch of different parts all at once in one or both 
IHU's.  This would also be a plausible explanation of why the IHU 
crashed, if enough memory errors happened all at once that the IHU 
was unable to resolve them, and if sensor interfaces got knocked out, 
it would also explain why some sensors are reading clearly 
out-of-band values.  Whether or not there is a workaround that will 
allow the sensors to be read is beyond me -- I'm not *that* familiar 
with the electronics -- but it certainly makes a lot of sense the 
more I think about it.  As long as none of the SRAM's have any stuck 
bits, the IHU crash should be a minor issue if anything .. the sensor 
issues may be more of a problem ..

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