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Re: AO-40 info from AMSAT-UK



At 11:53 PM 12/17/2000 , you wrote:
>on 12/17/00 10:37 PM, sco@sco-inc.com at sco@sco-inc.com wrote:
>
> >> Please note that this is a *software* watchdog. There is no hardware
> >> watchdog. If the IHU has crashed, than a RESET command can be issued from
> >> ground. This would be the last resort. It is a very fail-safe system, 
> which
> >> has been used before on AO-10 and AO-13. However, it was decided to check
> >> and analyze all other possibilities before issuing such a drastic command.
> >> There is no need to hurry and we don't want to miss any option...
> >
> > I may not be an engineer but know that NASA usually has two different
> > backup systems to the primary. Am I to assume that we did not even have one
> > backup to the software watchdog system, in case of computer failure? If so
> > I think we should fix that in any future sats.
> >
> > Still hoping for good news.
>
>No, I don't think that's correct.  Peter says it is a "fail-safe" system.
>Fail-safe by definition means there is redundancy built in.  Additionally,
>if you read on you'll see that there is also the master reset command that
>they can issue from the ground.

If the motor ran 3 minutes longer than planned could it have caused a heat 
or vibration problem to any critical components?

W4SCO

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