[rescue] Re: [geeks] Crap! Not again...

[Michael Free]

I was under the impression that the shuttle's computer systems were pentuple
redundant... 5 systems concurrent, an odd number to avoid a "mexican
standoff". This was before the latest refit however, when the wiring was
replaced, I don't know if it still uses that many.

It sounds to me that a pinhole in the left wing slowly spread, severing
wires and sensors as it went, until it finally weakened the airframe enough
that it failed.

I'm listening to the NASA briefing at the moment, and they're currently
discounting the lost piece of foam as to damage to the tiles.

Mike Free
----- Original Message -----
From: "Lionel Peterson" <lionel4287 at yahoo.com>
To: "The Rescue List" <rescue at sunhelp.org>
Sent: Saturday, February 01, 2003 4:18 PM
Subject: Re: [rescue] Re: [geeks] Crap! Not again...


> --- ed at the7thbeer.com wrote:
> > Got me to wondering if maybe the computer(s) screwed up and the bird
> > came in too hot.  Not that computers ever make mistakes, but poorly
> > coded software will.  And what an amazing way to sabotage something
> > as complex as the shuttle.  Change a decimal place in some code,
> > wait till it gets loaded and let it do the rest.
>
> Two words - triple redundant
>
> The shuttles mission critical systems are triple redundant (IIRC) -
> they have two computers that perform the calculation, then a third
> compares (or is it three, and a fourth compares, majority wins?)...
>
> Also, they are programmed by different teams, because a software bug
> would invalidate the redundancy in many cases.
>
> Also, the "Hacker Terrorist" (were it intentional) woul dhave to pass a
> security clearance check - a non-trivial effort, I assume.
>
> =====
> Lionel
>
> "Nothing would please me more than being able to hire ten
> programmers and deluge the hobby market with good software"
> Bill Gates, in "An OpenLetter to Hobbyists" dated February 3, 1976
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