Re: [PSUBS-MAILIST] New to PSUB (measurement units)

[Erik Muller <emm03@uow.edu.au>]

I agree somewhat.,but in any design process, murphys law
lurks. The only way around it is to make sure that you can
reduce the number of opportunities for something to go wrong.
The longer your conversion chain, the more opportunities there
are to make a mistake.  Converting between janskys and joule
distance is no big deal, radio and optical astronomers also
talk about spectra in terms of frequency and wavlength. These
all have direct, physical standards. A foot does not. It is
only (I think) belligerance and illogical inflexibility that
is the hiccup. Farenheit in particular defys common sense. I
thank god that we dont measure brightness temperature in
Farenhiet, this is an utterly meaningless unit.
                                    
I dont think that anyone can claim that it is ok to have to do
many conversions. The key point in the case of the mars probes
is that if the system was consistent from the beginning, the
problem would not have occurred. At least, not THAT particular
problem, one less. Scientists and engineers in NASA should
know better (sorry if that was you, but there you go, im sure
the lesson is well learned).
-------------------------------------------------
Hello
'subbers,                                                                 
                                                                                
        I was involved in the science part of this mission.
Anyone who          
thinks that unit conversion would be abolished by converting
to SI is fooling themselves. As a physicist, I find the
English system riddled with vertiginous wretching horror.
However, I can tell you we've had 'oops' with space telescopes
for example because someone forgot to convert Jansky's to
micro-joule angstroms or some such. Both of those are SI
units, but depending on your field (i.e. infra-red astronomer
vs. photo-electric engineer) you have a preference.
Conversions are necessary in any complex system at some point,
what's key is the processes that manage those conversions. 
       Bottom line: the problem isn't the measurement, it's
the management