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Old January 23rd 04, 01:04 AM
Gary W. Swearingen
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Default 'Spirit' Communications Emergency

(Remy Villeneuve) writes:

Is it possible for a stray/garbled signal from Earth to be
misinterpreted by the rover? I guess there's a CRC mechanism for
uplinks but... any thoughts?


Yes, it's possible, but like every other known risk, it should be a
small risk, with commonication errors probably much lower than most
risks. It was said at the briefing that the data is protected by ECC
code that correct single bit errors and detect double (often even
numbers of) errors per data block and I suppose there's other,
CRC-type checks too. And they didn't transfer much data up before the
error. Previously uploaded data (particularly software) had been
pretty-well checked out in the last many days. Cosmic ray problems
should be just as low risk.

I'm speculating that it was some circuit board problem that was bad to
start and got worse from the bouncing and explosive devices and
finally gave up when jostled by a wind gust or whirl or temperature
change (it was afternoon local time). Maybe some memory has been
lost, as the communication systems seem to be working OK and the
computer is working well enough to answer the phone, but it's not able
to send data to the communications systems. Probably caught in some
low-level "safe" mode, occasionally trying to exercise software that's
gone and going back to safe mode. But let's hope it's something
temporary. They might be able to reload software code and data, even
mapping out bad memory hardware, if needed.