
What really happened on Mars? (1997) - noir_lord
http://research.microsoft.com/en-us/um/people/mbj/Mars_Pathfinder/Authoritative_Account.html
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kahirsch
“We’ve been looking through the old Pathfinder software. We got duplicate
computers up and running for testing. Same computers they used to find a
problem that almost killed the original mission. Real interesting story,
actually; turns out there was a priority inversion in Sojourner’s thread
management and—”

“Focus, Jack,” interrupted Venkat.

Weir, Andy (2014-02-11). The Martian: A Novel (p. 121). Crown/Archetype.
Kindle Edition.

~~~
xenophonf
I couldn't put that book down. It was probably one of the best bits of hard
science fiction I've read recently.

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kenjackson
Ahh... The classic "better than we ever imagined" turns out to be a nightmare.
This should be required reading for those who test software.

~~~
kzhahou
I didn't understand that part. It describes "high data rate" as "best case".
Does "better than we ever imagined" means they were overflowing in good usable
data? Because too much data sounds like a problem.

Unrelated, note how difficult it is for people to accept 100% responsibility
for a problem. For example:

> Did we (the JPL team) make an error in assuming how the select/pipe
> mechanism would work ? Yes, probably.

There's no "probably"! A mistake was clearly made.

~~~
duaneb
This is science, all knowledge is both inductively reached and imperfect. More
people should use the word "probably"—if you're going to assign blame, which
is not always necessary, it is important to do so accurately.

~~~
reagency
_Everything_ is probability. Why since out some statements as deserving of
qualification?

You said all knowledge is inductively reached, why didn't you say "probably"?!

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ForHackernews
> No, we did not use the vxWorks shell to change the software (although the
> shell is usable on the spacecraft)

That adds new meaning to the phrase "remote shell". Can you imagine how
irritating the latency would be trying to use a shell on Mars?

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nivla
>Can you imagine how irritating the latency would be trying to use a shell on
Mars?

I can I have Comcast. But on a serious note I think for applications like this
a Puppet/Chef style recipe will be used. A complex series of checks and bounds
before and after the changes have been applied and if anything sightly goes
awry, revert back to the previous working condition.

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socceroos
RS6000 processor! Wow.... I remember doing work on one of these back when I
was in college. Turned out I became the only person in my state to be able to
maintain the old RS6000 machines.

...haven't touched or heard of one in over a decade.

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mwcampbell
Is an embedded real-time OS like VxWorks still used in this role on this kind
of mission today, or is a general-purpose OS like Linux used instead?

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transientbug
Pretty sure VxWorks is still used today for a lot of spacecraft; Curiosity[^1]
and at least at one point the SpaceX Dragon capsule[^2] it looks like.

^1:
[http://www.windriver.com/announces/curiosity/](http://www.windriver.com/announces/curiosity/)
^2:
[http://www.spacex.com/sites/spacex/files/pdf/DragonLabFactSh...](http://www.spacex.com/sites/spacex/files/pdf/DragonLabFactSheet.pdf)

