

NASA Declares End to Deep Impact Comet Mission - gliese1337
http://news.nationalgeographic.com/news/2013/09/130920-deep-impact-ends-comet-mission-nasa-jpl/

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hcarvalhoalves
> "Basically, it was a Y2K problem, where some software didn't roll over the
> calendar date correctly," said A'Hearn. The spacecraft's fault-protection
> software (ironically enough) would have misread any date after August 11,
> 2013, he said, triggering an endless series of computer reboots aboard Deep
> Impact.

Men build a $267m spacecraft, send it to space, target it at a meteor, manage
to make it inspect the meteor upclose at thousands of kms/hour... and still,
writing correct software is an impenetrable problem.

Amazing.

~~~
binarymax
Not only that, the problem was _date /time_ related. Dates and times seem to
be one of the most tricky things to account for and are consistently taken for
granted, introducing unexpected errors. You would think by now someone would
have made a fortune developing a robust radiation tolerant datetime IC, that
has enough bits to count milliseconds from the big bang until the estimated
end of the universe.

~~~
projectileboy
As Peter van der Linden says in his (excellent) book Expert C Programming:
"Anyone who thinks programming dates is easy to get right the first time
probably hasn't done much of it."

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mturmon
It had been retargeted, with its last couple kgs of fuel, to a potential
year-2020 asteroid encounter:

[http://spaceflightnow.com/news/n1112/17deepimpact/](http://spaceflightnow.com/news/n1112/17deepimpact/)

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anon-140
Here is the latest SCLK kernel for the mission:
[http://naif.jpl.nasa.gov/pub/naif/DEEPIMPACT/kernels/sclk/DI...](http://naif.jpl.nasa.gov/pub/naif/DEEPIMPACT/kernels/sclk/DIF_SCLKSCET.00121.tsc)
and if you are not among the JPL/NAIF/SPICE cognoscenti and don't have the
numbers sense to grok it from that file, here is one of the SPICE required
reading files:
[http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/req/sclk.ht...](http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/req/sclk.html)
to get you started. SPICE is one of the most robust, well-commented and
-documented toolkits I have ever seen. There is more information about the
spacecraft clock in the PDS archives e.g.
[http://naif.jpl.nasa.gov/pub/naif/pds/data/di-c-
spice-6-v1.0...](http://naif.jpl.nasa.gov/pub/naif/pds/data/di-c-
spice-6-v1.0/disp_1000/catalog/spiceds.cat)

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pintglass
> "I'm a little biased, but I think the taxpayers saw very good value from
> this mission,"

I'd say that was biased. I personally would have rather $267 million be spent
on something more permanent and practical. How about spending it on our Earth-
based telecopes?

~~~
zalzane
Because pretty much everything that was possible to discover with earth based
telescopes has been discovered. Sure, you can always do "science" with earth-
based telescopes - reconfirming existing theories, making sure theoretical
data matches up to real observed data, but there's a limit to how much
"discovery" can actually be done.

Extra-planetary experiments like the deep impact mission allow scientists a
glimpse at new experimental data that can confirm theories that there is no
other way to confirm. Sure, you can observe a comet's tail to figure out its
surface composition - but that has limited resolution and many elements simply
can't be detected that way. This isn't even taking into consideration all the
sub-surface elements that would be utterly impossible to detect from
observation alone.

In essence, even if the Deep Impact mission mostly failed and scientists only
gathered a limited amount of data, it is still very much worth its value when
the alternative of building permanent terrestrial telescopes does nothing more
than confirm data that has been confirmed countless times in the past.

~~~
Sharlin
> _even if the Deep Impact mission mostly failed and scientists only gathered
> a limited amount of data_

I don't think you meant it that way, but I'd like to clarify that Deep
Impact's mission most definitely did not fail. The spacecraft survived for
eight years after it completed its primary objectives in 2005.

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projectileboy
Does anyone know more about the software? (Operating system, language, etc.)

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ArekDymalski
unbeliveable. whole world was alerted about the upcoming y2k doom and nothing
particularly spectacular happened. but those guys managed to do it anyway.
several yrs later.

~~~
Jgrubb
The y2k mention was an analogy, not literally the same bug, because as you
correctly stated it would be impossible to trip over the y2k bug several years
after y2k. It was a calendaring bug.

