
The First Bug on Mars - AndreyKarpov
http://www.viva64.com/en/b/0462/
======
junke
From "REALLY REMOTE Debugging: A Conversation with Glenn Reeves" (2010) [0]:

 _We did see the problem before landing, but could not get it to repeat when
we tried to track it down. It was not forgotten nor was it deemed unimportant.
Yes, we were concentrating heavily on the entry and landing software. Yes, we
considered this problem lower priority. Yes, we would have liked to have
everything perfect before landing. However, I didn 't see any problem, other
than that we ran out of time to get the lower priority issues resolved._

 _We did have one other thing on our side -- we knew how robust our system was
because that is the way we designed it. We knew that if this problem occurred,
we would reset. We built in mechanisms to recover the current activity so that
there would be no interruptions in the science data (although this wasn 't
used until later in the landed mission). We built in the ability (and tested
it) to go through multiple resets while we were going through the Martian
atmosphere. We designed the software to recover from radiation induced errors
in the memory or the processor. The spacecraft would have even done a 60-day
mission on its own, including deploying the rover, if the radio receiver had
broken when we landed. There were a large number of safeguards in the system
to ensure robust, continued operation in the event of a failure of this type.
These safeguards allowed us to designate problems of this nature as lower
priority. We had our priorities right. _

[0] [http://www.drdobbs.com/architecture-and-design/really-
remote...](http://www.drdobbs.com/architecture-and-design/really-remote-
debugging-a-conversation-w/228700403)

~~~
JoeAltmaier
I don't understand. Flip a flag. That was the bug fix. They instead tested
around it, considered it a reasonable risk, launched a rocket to Mars _without
flipping the flag_. What could they have been thinking.

~~~
maxander
First, note the phrase "could not get it to repeat when we tried to track it
down." Secondly, I'm pretty sure that that flag wasn't just labelled
SERIOUS_RUNTIME_ISSUE_ACTIVE; there were presumably other good reasons for the
flag to be set the way it was, and other serious problems that flipping it
_might_ have caused, as far as they could determine pre-launch.

~~~
JoeAltmaier
Nope. It was a semaphore, and it had a flag, and it was set wrong (contrary to
policy), and they noticed it and documented it. Whether or not they could
reproduce the problem _they had already predicted_ the only reason NOT to fix
the bug was, institutional inertia. I.e. can't change code because the process
says we cant without an elaborate ritual.

------
xssfoofoo
Is it just me that finds this 'article' completely unreadable? There are
diagrams given with very little explanation and there seems to be very little
to guide the ready through what the problem was and how it was solved.

------
junto
On a side note, I'm guessing many of us have seen the movie "The Martian", but
whether you enjoyed it or not, I would highly recommend the novel. The detail
that goes into how he survives is amazing, which is somewhat missing in the
film.

~~~
junke
Yes, the book is great.

The movie had other good things, like PVS/Lisp code in a spaceship ;-)

[http://scifi.stackexchange.com/questions/115255/what-
program...](http://scifi.stackexchange.com/questions/115255/what-programming-
language-is-used-in-the-martian)

[https://www.reddit.com/r/lisp/comments/3nnvnp/fluff_anyone_e...](https://www.reddit.com/r/lisp/comments/3nnvnp/fluff_anyone_else_notice_lisp_in_some_of_the_code/)

[https://github.com/nasa/pvslib/blob/master/power/exponentiat...](https://github.com/nasa/pvslib/blob/master/power/exponentiation_aux.prf)

------
spraak
The title is borderline clickbait considering the search for life on Mars..
It's really the "First [Computer] Bug on Mars".

~~~
blowski
I assumed that if life had been found on Mars, I wouldn't be hearing about it
from an un-famous blog on Hacker News. It's just a pun, and that doesn't make
it clickbait, just good headline-writing.

