[oclug] Mars

[Matthew Wilcox]

On Tue, Jan 06, 2004 at 12:44:38AM -0500, Robert Brockway wrote:
> Rockets going into space (and I would hope mars landers/rovers) run
> multiple software packages on multiple platforms all written to a single
> spec operating in a fail-over configuration.  The number of such packages
> has typically been 5 or 7 I think.  This is true for engine control
> systems, navigation systems, etc. This is to protect against any single
> flaw/vulnerability in software or hardware causing a rocket to
> catastrophically fail.
> 
> So it is entirely possible an OSS OS is on many of these craft along with
> other OSes that shall go unnamed.

Um, kind of ... what I heard was 5 computers, 4 running the same
combination and one completely independent.  But you have to bear in
mind that these computers have the processing power of a small peanut.
They don't run general purpose operating systems.  They're space-hardened
and safety-critical.

landers and unmanned vehicles are merely mission-critical.  i suspect
other engineering decisions (such as cost) prevent there from being 5
independent systems.  i would expect them to run only one OS.

the "independent systems buys you more reliability" thinking is slightly
a myth anyway.  i've read about studies that give the same problem to
20 different students and 19 of them coming back with the same bug in
their program.  nothing substitutes for good testing, remember Ariane 5?

I have some amateur satellite contacts, would there be interest in
getting someone up here to talk about use of Linux in the amsat community?

-- 
"Next the statesmen will invent cheap lies, putting the blame upon 
the nation that is attacked, and every man will be glad of those
conscience-soothing falsities, and will diligently study them, and refuse
to examine any refutations of them; and thus he will by and by convince 
himself that the war is just, and will thank God for the better sleep 
he enjoys after this process of grotesque self-deception." -- Mark Twain