Re: computer language used to program Mars Lander

["Brian" <phaedrusalt@hotmail.com>]

<jhc0033@gmail.com> wrote in message 
news:807ef880-b2ac-4ac6-877c-21274e8ff4ab@d77g2000hsb.googlegroups.com...
> On Jul 14, 4:49 am, Nick Keighley <nick_keighley_nos...@hotmail.com>
> wrote:
>
>> contrary to popular expectations space probes are very
>> conservative in their use of technolgy.
>
> I disagree. Actually, the space industry will try anything and stick
> with it until stuff explodes (Ariane rocket) or crashes into the wrong
> celestial body because of faulty software. They did use Ada widely
> before, and they even programmed some of their probes in Lisp. Seems
> like C is the new fad there. Wait until they get bitten by macros and
> dangling pointers.

And I disagree with your disagreement.  The Ariane rocket disaster is a good 
example of trying to migrate existing software on a "known" platform in 
response to a business situation.  Also, the crashes you refer to "because 
of faulty software" are examples of software that wasn't adequately tested 
before implementation in order to comply with non-changing, and 
non-changeable, mission requirements.  Celestial mechanics won't let you 
slip your ship date!

JPL, along with the rest of NASA has an extraordinary success record with 
their software.  It would be stunning in any kind of endeavor, but is 
especially so when you consider the kinds of missions, and the kinds of 
things that happen with their funding and manpower on a yearly basis.  Then, 
just to make the engineering problem a bit more interesting please remember 
that there isn't a lot of hardware that functions in that environment, and 
it's a few million miles from anybody who might be able to hit CTRL-ALT-DEL. 
With all this in mind, I think that these guys deserve a lot of respect.

So, why did they choose C for this application?  I wasn't there when the 
decision was made, but I'd suspect that it was the language that their 
coders were most familiar with, the language that had the right libraries 
for their application, and the language that they felt was most appropriate 
for this application.  In other words, good engineering judgment.

Give 'em their "props", okay?

Brian