View Full Version : ISS Computer failure: how Do Triply-Redundant systems fail?
06-15-2007, 08:32 AM
I heard the news about the ISS problems-the russian engineers are working like mad to find a fix. my question; how do three seperate computers fail, all at the same time? probabbility-wise, that ought to be impossible! tahe computer no. 1-let's say it has a 0.01% chance of failure, as do no.s 2, and 3. multiply the probablilities, and you have a very LOW number-like 1 x 10 exp (-12). How does such an event take place? :confused:
06-15-2007, 08:39 AM
It's not just random bug, so probability calculations doesn't fit at all. It's probably that bug causes computer to crash under certain conditions, so when this conditions occur (like installing new solar panel) computer crashes, then backup computer crashes, then secondary backup crashes and voila! - complete crash.
06-15-2007, 09:38 AM
I was just reading the news about this. Apparently the solar panels are causing interference in the computers, and the Russians are stating that Nasa knew this when compressors located near the computers during ground tests would crash the system when the compressors would turn on.
This is just what I read, I make no claims to its actual validity.
06-15-2007, 09:50 AM
According to NASA, the computers aboard the Space Station appear to be sensitive to the noise created by the electrical interference from the solar arrays.
"They did find that these were sensitive to this power noise and in fact, a couple of instances on the ground where activiating compressors around the test stands would cause them to have upsets and shut themselves down," Mike Suffredini, NASA Space Station Program Manager, told ABC News. http://abcnews.go.com/Technology/story?id=3281714&page=1
06-15-2007, 10:21 AM
http://abcnews.go.com/Technology/story?id=3281714&page=1"They did find that these were sensitive to this power noise ..."That was my first thought. They are all on the same power source. A system isn't really redundant unless it has separate power sources and wiring. From the sound of it the solar panels are putting noise on the power line that the computers can't tolerate.
Is this another example (such as the O-ring and foam breaking off) of NASA knowing about a defect and hoping for the best?
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