Re: Ariane5 FAQ

["Robert I. Eachus" <rieachus@attbi.com>]

Hyman Rosen wrote:
> Mike Silva wrote:
> 
>> So you are arguing that, lacking written documentation to the
>> contrary, any piece of code should be assumed capable of handling all
>> possible input values in a way that is appropriate to all possible
>> systems in which the code is employed.  Tell me, honestly, would you
>> fly in a rocket designed under such assumptions?
> 
> 
> But we're not talking about "any-all". This was a combined
> hardware and software module being moved from one rocket
> version to the next.
> 
>> the Ariane-5 people had no legitimate reason to assume that what
> 
>  > the code did would also be right in the Ariane-5 system.
> 
> And yet they acted that way. That argues that they did have
> a legitimate reason. Even though it turned out to be wrong
> in retrospect. As I keep saying, there is a difference between
> "no reason to assume it will work" and "reasons why it will
> not work".

Yes, several someones assumed that the software HAD been designed with 
the Ariane 4 and Ariane 5 requirements in mind.  But a 
political/financial decision was made not to allow the team developing 
the SRI to have access to the Ariane 5 performance data.

The reasoning behind that decision was that it would give them a leg up 
on other bidders for portions of the Ariane 5 software development. 
This was probably true.  So the requirements scrub should have been done 
by the Ariane 5 developers.  But that never got done because they did 
not have access to the SRI documentation, just the source code.  THAT 
was the monumental stupid blunder.  Eliminating (for financial reasons) 
the scheduled tests in which the guidance system would be ground tested 
with Ariane 5 trajectory data was the (third) shoe.  It took all three 
pieces to make a disaster, and there is (fairly obviously) no evidence 
of collusion.

-- 

                                           Robert I. Eachus

�In an ally, considerations of house, clan, planet, race are 
insignificant beside two prime questions, which are: 1. Can he shoot? 2. 
Will he aim at your enemy?� -- from the Laiden novels by Sharon Lee and 
Steve Miller.