[tz] Deep Impact: wrong time zone?

Paul Eggert eggert at cs.ucla.edu
Sun Sep 22 22:36:39 UTC 2013

Deep Impact's chief mission scientist Mike A'Hearn
said, "Basically, it was a Y2K problem, where some
software didn't roll over the calendar date correctly."
The fault-protection software misread any dates
after 2013-08-11, and the misreads triggered an
endless series of computer reboots.

The failure was in the fault-protection software -- i.e.,
if they hadn't tried to prevent failure, Deep Impact
would still be working.

What timescale wraps around on 2013-08-11?  Perhaps
it was something mission-specific, such as the number
of deciseconds since the mission began, or the number
of milliseconds since the previous reboot, and this was
bowdlerized into "calendar date" for the general public.

My source:

Vargano D.
NASA Declares End to Deep Impact Comet Mission.
National Geographic 2013-09-20

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