[time-nuts] Standards for units

SAIDJACK at aol.com SAIDJACK at aol.com
Wed Apr 4 01:46:57 EDT 2007


 
In a message dated 4/3/2007 19:29:25 Pacific Daylight Time, didier at cox.net  
writes:

An  Arianne 5 rocket had to be destroyed with its cargo when it veered 
off  course because of a faulty conversion from English to metric in the  
guidance software. What a bummer!
I hate it when that  happens!!!


Hi Didier,
 
actually unless there was a second explosion I don't know about, the first  
Arianne-5 proto-rocket exploded due to a variable parameter overflow  (missing 
saturation check) in a calculation.
 
The conversion problem you mentioned happened on a Mars mission.
 
There was a lengthy and technically detailed report in the German CT'  
magazine, it said the designer of the routine proved extensively that the  routine 
would never overflow on Arianne 4 due to it's flight configuration, and  in 
fact it never did.
 
He left the company, and the guys who followed just copy-pasted his code  
into the Arianne 5 flight software were the code did overflow due to missing  
saturation tests and a different flight configuration.
 
BTW: I didn't expect my email about our strange US units to start such a  
lengthy discussion on the board...
 
bye,
Said



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