Re: Ariane5 FAQ

["Bobby D. Bryant" <bdbryant@mail.utexas.edu>]

On Wed, 23 Jul 2003 19:24:17 +0000, Robert I. Eachus wrote:

> Tarjei T. Jensen wrote:
>> Robert I. Eachus  wrote:
>> 
>>>Also the SRI software used the Ariane 4 moments of inertia in its
>>>control laws.  The report seems to indicate that there was a 10 Hz
>>>ocillation building up due to this.  If it had gone on would that have
>>>been sufficient to destroy Ariane 501?  Probably.
> 
>> I believe that I saw a program on Discovery in which it was claimed
>> that the oscilations would eventually have destroyed the rocket.
> 
> As I said, probably.  But if it didn't, the oscillations would result in
> the Ariane 5 not reaching the expected orbit.  Less dramatic, but just
> as fatal for the payload.
> 
> And that is why I keep posting on this topic, hoping that everyone will
> "get it."  The actual failure scenario is interesting, but the fact that
> there were two others waiting to happen means that you should look at
> what they all have in commmon:  The missing "scrub" of the SRI
> specifications against the Ariane 5 requirements.  We are talking about
> something that should have taken about a week for three or four people,
> if there were no major discrepancies.

And of course, if there *were* major discrepancies it becomes even more
important to have done it.

> Of course, in this case, the bill would have been higher, but a lot less
> than the bill for the failure.

-- 
Bobby Bryant
Austin, Texas