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Re: AO-40 telemetry interruption



>From: "John P. Toscano" <tosca005@tc.umn.edu>
>We now know that there *IS* a problem that led to the interruption
>of telemetry, not just testing of the UHF transmitter, not just
>another IHU2 crash, not just awkward antenna squint angles.
>
>But we ALSO know that there is an incredibly talented, unbelievably
>devoted group of people who are working on the problem.  Unless they
>tell us to give up hope, DON'T GIVE UP HOPE!  Give them a chance to
>do what they need to do, trust in their skills.

John,

That was a very fine message.  And certainly we can only wait with the
command crew to see what happens on Saturday.

Trying to decipher the announcement from Amsat leads me to speculate a
little {with your permission}:

My best guess {and I am not an expert on the systems in AO-40, so I may be
completely wrong}, is that there has been a controller shutdown that has
disabled the RF system, perhaps in some "fail-safe" mode.  I would guess
that the designers put some redudancy into the hardware and software
design.  Also, perhaps the software is timed to go to certain recovery
routines after not hearing from a ground station over a certain time period.

Or perhaps they have uploaded a specific software recovery command.

I would try not to hazard a guess on what caused the shutdown, but they
were involved in remotely studying the propulsion system and possibly that
required commanding different states of the system.  Perhaps an erroneous
command crept in somehow.  They have the most information on this...not me,
plus the expert knowledge of how things work.

Now these "guys" have been living with this satellite for years getting it
ready for launch.  They know it inside out.  I am confident that they are
working on several approaches to recovery.  I know it must be extremely
stressful, but only they can fix it!

I know that we all wish them success!

For now we will have to wait.  Later on I'm sure we will be filled in on
what transpired, to the best of their knowledge.  For now I'm content to
let them work on it...unmolested.  I hope that my speculation will not
cause any harm to this effort.  I suspect that there are many things to be
tried before coming to any conclusion on the long term health of the
satellite.

HOPING FOR THE BEST!
Ed  

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