Re: computer language used to program Mars Lander

[pjb@informatimago.com (Pascal J. Bourguignon)]

"jhc0033@gmail.com" <jhc0033@gmail.com> writes:

> On Jul 23, 7:43 am, Michael Oswald <muell...@gmx.net> wrote:
>> I mean, I work in the space
>> business (although not directly on on-board software but rather mission
>> control software and testing equipment) but I haven't heard of Lisp
>> usage. Would definitely be a 'nice to know' for me.
>
> Probably because they weren't too successful. I personally think Lisp
> is super-cool, but inappropriate for space (or any reliability-
> sensitive work).
>
> If I remember correctly, when they used Lisp in the probe, there was a
> bug and they used Lisp's live patching and interactive debugging to
> fix it, so they only missed their target by a quadrillion miles
> instead of missing it by a gazillion miles.

It wasn't the purpose of the mission to hit the target, but to fly by.


> On the other hand, the bug wouldn't have happened in the first place,
> if they used a good static language. I'll let someone who knows better
> fill in the details (that's why I added comp.lang.lisp to the groups)
>
> Happy space exploration and exploitation!

http://en.wikipedia.org/wiki/Deep_Space_1

http://www.nasa.gov/lb/centers/ames/news/releases/1999/99_37AR.html
REMOTE AGENT EXPERIMENT MEETS ALL OBJECTIVES

http://web.archive.org/web/20010923215958/http://rax.arc.nasa.gov/

http://www.flownet.com/gat/jpl-lisp.html

Be sure to read the description of the bug:

http://web.archive.org/web/20061106012026/http://ic.arc.nasa.gov/publications/pdf/2000-0176.pdf

It has nothing to do with Lisp per se.  It could have occured with any
other programming language.  Now, the question is how do you correct a
dead-lock on a running system compiled from Ada code, 3 second-light
away, without rebooting it?  This is what lisp allowed for this space
probe, and what lisp allows also for running web servers.

-- 
__Pascal Bourguignon__