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ISS Computer Failure
A number of readers wrote us with news of the computer problems on the International Space Station. Space.com has one of the better writeups on the failure of Russian computers that control the ISS's attitude and some life-support systems. Two out of six computers in a redundant system cannot be rebooted. The space shuttle Atlantis may have its mission extended until the problem is fixed. A NASA spokesman was optimistic that the problem can be resolved; worst-case scenario would be for the shuttle to evacuate everyone onboard the ISS. Engineers are working on the theory (among others) that the failure may have been triggered by new solar panels installed earlier in Atlantis's mission.
Hopefully they're starting with their DFMEA documentation... "guessing" at the problem and having "theories" is probably not a good way to go. Also, it's apparently a common-mode failure, which you shouldn't have in a safety-critical system; generally this is avoided by having different computer hardware and/or completely different code to do the same tasks.
Quite unfortunate that it seems like systems engineering is lacking in more and more disciplines recently, although I suppose it makes good systems engineers more valuable.
My list for this would be something like: "Computer doesn't boot." Possible reasons: "No Power", "Insufficient power", "Corrupt memory", "Broken circuits", etc. Then you go down that tree further and find the root cause. The most disturbing thing is that they had such a major common-mode failure...whatever happened to the "no single points of failure" mantra?
* sigh *
"There are a dozen opinions on a matter until you know the truth. Then there is only one." - CS Lewis (paraprhase)
At this point, as a US taxpayer, I'd much rather see the ISS finished rather than just leaving it up there as a pile of space junk.
It's kinda like finding out your house you're current building will cost twice as much as normal.
Do you just leave it half finished and abandon it or do you keep pumping money into it?
No.
On NASA's manned space equipment you will find no software that is not controlled by NASA. These folks don't just run a few tests. They spend thousands of dollars per SLOC in testing. They actually mathematically prove their software's correctness. Perhaps the Russian agency's quality isn't quite as high, but I still doubt their (or anyone else's) systems onboard the ISS have any OS at all. Most likely they are all custom embedded systems.
I'd council against jumping to conclusions about the cause of this solely based on the Russian origin of these systems. I remember a lot of people did that with the early Ariane crash based on it being written in Ada, and ended up looking pretty silly when the problem turned out to be some ported code that wasn't rewritten properly for the new platform.
Evacuating ISS would be a very bad thing to have happen. The crew would be fine, as this luckily happened with a shuttle in dock, which can act an emergency lifeboat for the whole crew (plus the Soyuz that's up there with them, if things got too crowded on Atlantis). The biggest problem would be for the hardware - without people up there to keep maintenance tasks going, the station would need to be completely shutdown save for a few critical systems (attitude control, the NH4 cooling systems, power, etc.). In this case, some of those few critical systems are what seem to be giving the trouble.
Evacuating ISS is always a last resort, because should something happen to it while unoccupied, it'd be a total loss. We won't have another shuttle ready for a month or so, and I believe the Russians just recently did a Soyuz exchange, so there'd be no quick return, even if the problems were fixed. With attitude control in question, it could become too unstable for even a shuttle or Soyuz docking to occur.
The first piece of the space station was Zarya, the Russian control module that was launched into orbit November 20, 1998. A few weeks later, on December 4, 1998, the U.S. module Unity was launched into space. On December 7, 1998, the two modules were connected.
That makes the ISS just over 8 years in service.
How old is Atlantis?
Space Shuttle Atlantis has completed 27 flights, spent 220.40-days in space, completed 3468 orbits, and flown 89908732 miles in total, as of September 2006. Atlantis visited visited MIR in 1997!
Atlantis is 23 years old as of last April. 21 years in service. More than twice as old as the ISS.
Now, tell again - which is the real bucket of bolts? ISS or Atlantis?