Author Topic: GNC Errors  (Read 3871 times)

Offline rdale

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GNC Errors
« on: 09/26/2008 08:03 pm »
Due to some errors overnight, GNC 1 has been taken off as primary and GNC 2 activated. They disabled GPS as a possible cause, but problems could occur again so that's why GNC 1 is still running in a backup config.

Last night they had to hand over to the Russian segment and go over to low-data rate, but with the current config -- a repeat error on one GNC would just switch to the backup and not the Russian side.

They'll troubleshoot overnight and Saturday, but if no fix by Sunday they'll need to roll back all the MDM's to the last version and go from their.

Strangely - no mention in today's ISS Daily Report as it says everything is running fine. This came from what I heard during the wakeup call, and more info from the daily planning conference this afternoon.

Offline erioladastra

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Re: GNC Errors
« Reply #1 on: 09/27/2008 12:56 am »
Due to some errors overnight, GNC 1 has been taken off as primary and GNC 2 activated. They disabled GPS as a possible cause, but problems could occur again so that's why GNC 1 is still running in a backup config.

Last night they had to hand over to the Russian segment and go over to low-data rate, but with the current config -- a repeat error on one GNC would just switch to the backup and not the Russian side.

They'll troubleshoot overnight and Saturday, but if no fix by Sunday they'll need to roll back all the MDM's to the last version and go from their.

Strangely - no mention in today's ISS Daily Report as it says everything is running fine. This came from what I heard during the wakeup call, and more info from the daily planning conference this afternoon.

To clarify, new software, release 7, was loaded to the GNC and Command and COntrol (C&C) MDMs this week.  As soon as the nvaigation data is enabled the GNC MDMs have been failing.  There is clearly a software error.  We are discussing whether we stay on it with nav disabled or roll back.

Offline rdale

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Re: GNC Errors
« Reply #2 on: 09/27/2008 01:18 am »
Thanks for filling in the gaps... Is this not a "problem" or did the status report writer just not know about it? What is the Sunday "deadline" referenced for fix or rollback?

Offline rdale

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Re: GNC Errors
« Reply #3 on: 09/27/2008 02:46 pm »
They interrupted the start of today's DPC to ask the crew to stay off the PCS's while they install an R7 patch over the next hour...

Offline rdale

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Re: GNC Errors
« Reply #4 on: 09/27/2008 11:13 pm »
Today's ISS report says there is a possible debris avoidance manuever on Monday - which might be why they want to rollback tomorrow if fix didn't take? Still no mention of GPC problems for some reason...

Offline rdale

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Re: GNC Errors
« Reply #5 on: 09/28/2008 12:31 am »
Late today they took Greg to private conference to discuss R6 rollback options.

Offline erioladastra

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Re: GNC Errors
« Reply #6 on: 09/28/2008 12:55 am »
Late today they took Greg to private conference to discuss R6 rollback options.

The R7 patch had nothong to do with the problems.  This was a planed patch to the crews laptops to work with the new software.  Problem still not known.  Debris is not an issue.  Sunday was picked because weekend is less impact.  Likely stay in this config (using Russian nav data) until problem understood.  Yes this is a problem, have no idea why the status report didn't list - don't even know who writes those.

Offline rdale

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Re: GNC Errors
« Reply #7 on: 09/28/2008 01:35 am »
Thanks again... Why are some non-medical/personal conferences taken to private? Even heard them tell him to go to Columbus for some of the discussion about this yesterday.

Offline rdale

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Re: GNC Errors
« Reply #8 on: 09/29/2008 11:07 pm »
Any update on this? I didn't hear anything yesterday, and missed the morning conference (evening one today had no news, and the daily status report says all is working fine.)

Offline Life_Support_32

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Re: GNC Errors
« Reply #9 on: 09/30/2008 12:22 am »
The vehicle is in a safe configuration right now and flight controllers are going to hold off on changing the situation until testing can be done in the test models to replicate the problem and develop the fix.  As of this afternoon, they have not been able to replicate the problem.

Offline rdale

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Re: GNC Errors
« Reply #10 on: 10/09/2008 01:47 am »
GNC Issue Troubleshooting:   After recent intermittent anomalous behaviors of both GNC MDM (Guidance, Navigation & Control Multiplexer/Demultiplexer) computers, flight controllers uploaded a software patch to the MDMs to gather more data for diagnostic analysis.  The patch will not be exercised on orbit until after the Soyuz 16S undocking.

Offline erioladastra

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Re: GNC Errors
« Reply #11 on: 10/10/2008 12:00 am »
GNC Issue Troubleshooting:   After recent intermittent anomalous behaviors of both GNC MDM (Guidance, Navigation & Control Multiplexer/Demultiplexer) computers, flight controllers uploaded a software patch to the MDMs to gather more data for diagnostic analysis.  The patch will not be exercised on orbit until after the Soyuz 16S undocking.

Not quite right.  The patch is loaded.  If a GNC should fail, it will allow us to capture more data.  However, some of the testing we want to do that might induce a failure (since it can't be reproduced on the ground) will be deferred until after 16S undock.

Offline rdale

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Re: GNC Errors
« Reply #12 on: 10/10/2008 12:52 am »
At least the daily reports finally acknowledged there is a problem - we can't ask for everything ;)

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