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DrQuine
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Preventing Upside-Down Sensors
DrQuine   7/10/2013 4:43:31 PM
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The use of keyed connectors that can only be assembled one way is a good precaution to prevent reversed connections.  Of course, if the connector is wired backwards that won't help.  The second essential step is to gather baseline data and confirm that the device is operating properly. If indeed the sensor was installed upside-down, it should have been reported inverted data when standing on the launchpad. Exhaustive testing certainly proves its worth if it can catch a tiny error before it causes a huge failure.

CMathas
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Re: Preventing Upside-Down Sensors
CMathas   7/10/2013 6:11:11 PM
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Huge failure is right. One would think that there would be several tests and confirmations in place before actual launch. That's a huge loss of resources based on something that should have been easily caught.

_hm
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CEO
Quality Control and testing in Space Electronics
_hm   7/10/2013 8:37:23 PM
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Quality control in Space electronics is very essential. And this type of mistakes are often discovered. One common exapmple is polarized capacitor. Many times, they are mounted with polarity reversed.

Another aspect is testing. Testing is very improtant in this type of critical missions. It should try to encompass all this possibilities. And yes, poke yoke problem must also be avoided.

Tom Murphy
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Dubious Source
Tom Murphy   7/10/2013 9:45:20 PM
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I'm not sure I'd put a lot of stock in an unidentified source and the Interfax news agency. I mean -- these are rocket scientists we're talking about, and they know how to install sensors.  In any case, how would they know at this point?

LarryM99
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CEO
Re: Quality Control and testing in Space Electronics
LarryM99   7/10/2013 11:55:08 PM
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We can't necessarily be too smug about this. I seem to remember an American Mars probe that sailed right past that planet because someone put a period instead of a comma in a line of FORTRAN code. I have had friends that worked on the Saturn 5 that left because of the tension of building systems that could never be completely tested prior to a launch. We may be better off today with a combination of more experience and better test equipment, but we are also building more complex systems.

Kevin Neilson
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Manager
Genesis
Kevin Neilson   7/11/2013 12:45:56 AM
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Wait a second--I hope this isn't true, because this is exactly what happened with the Genesis probe.  It returned to earth and the drogue was supposed to come out after it had decelerated to a certain speed, but the accelerometers were mounted upside down so the deceleration was interpreted as acceleration and the drogue never came out and the probe cratered in the desert.

Sanjib.A
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CEO
Re: Dubious Source
Sanjib.A   7/11/2013 1:18:21 AM
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@Tom: I agree with you. I am a bit skeptic about the source, which has pointed to an important sensor getting installed "Up-side Down" as the cause of the failure. Why I think so?...several reasons. One is already mentioned by Tom. Also:

1. There should have been well-established processes for design, development and manufacturing space equipments as this kind of space programs deal with huge money, reputation and safety. The process should have been rugged enough to prevent this kind of human error. If not prevented, atleast, it should have been caught in inspection or some kind of quality checking/reviews.

2. Even if it was a mistake, I think design should have had redundant sensors to take care of this kind errors. Hope not all of those were mounted "upside-down"...otherwise there must had been a serious process gap somewhere.

I don't think this kind of error getting un-detected is something which could be expected from a well settled space organization isn't it?

Tom Murphy
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Blogger
Re: Dubious Source
Tom Murphy   7/11/2013 1:28:08 AM
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Good point, Sanjib.  You would think that there would be redundant systems. In the US, it's standard practice to have triple redundancy on space probes. And the monitoring stations on the ground watch every indicator.  There is certainly a possibility that this report is true, but I think there is a larger chance that the report is based on poor information.

Kevin Neilson
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Manager
Re: Dubious Source
Kevin Neilson   7/11/2013 3:34:46 AM
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Genesis had redundant accelerometers.  They were all mounted backwards.

prabhakar_deosthali
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CEO
Re:
prabhakar_deosthali   7/11/2013 7:23:32 AM
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It is very difficult to believe that such a mistake could have been made !

It will be interesting to know the design of the sensors- where there was an indication of how to mount them . If the basic instructions has been overlooked then it shows a poor standard of inspection and testing of a billion dollar product

 

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