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Re: Rocket Science



 
>  > The topic is hypergolic propellents. The shuttle OMS and RCS utilize
>  > monomethylhydrazine (MMH) and nitrogen tetroxide (n2o4), which, when mixed,
>  > ignite producing thrust. I have not been able to discover (even from some
>  > NASA folks) what the reaction product(s) of MMH + N2O4 is(are).
> 
> The nitrogen tetroxide is the oxidizer, so that the monomethylhydrazine
> can burn in the vacuum of space.  MMH is a simple molecule, CH3-NH-NH2,
> so I imagine that the combustion products are simply things like CO,
> CO2, H2O, NH3, and other oxides of nitrogen (NO, NO2).

Just a wild guess on my part, but I'd wonder whether N2 might be a product, ie from N2O4? 
N2 is such a stable molecule, it might be a driving force for the release of oxygen.
 
>  > Another curiosity on a similar topic is my shuttle toxicology book lists
>  > both hydrazine and monomethylhydrazine as shuttle hazards. I can only find
>  > references to the MMH being onboard. Anyone know if there really is
>  > hydrazine present and what shuttle system it's used for?
> 
> My guess is that they are using the term "hydrazines" as a generic
> term to encompass several related compounds.  When I looked up
> monomethyl hydrazine in the toxicology reference PoisIndex, the
> hydrazines are treated as a group with similar properties.  

My guess is that the monomethyl hydrazine is not pure, but rather a mixture of the two. I 
would guess that it would be expensive to make pure monomethyl in large quantities like 
that without impurities, and hydrazine and other hydrazines could be likely impurities. 
They probably have to list all constituents of the mixture.

I used to watch the shuttle landings on NASA-TV, and they used to wait for long periods 
of time, like 45 minutes, before sending people in to open it up. Usually they would send 
in a small contingent with detectors looking (according to the NASA-TV announcer) for 
leaking toxic hydrazine propellant.  Interestingly, in recent landings, they don't seem 
to spend so much time sniffing for the propellant, so perhaps they have developed faster 
ways of detecting it, or perhaps they changed the propellant mixture.


************************************
*    Bill Jones   Sweden Maine     *
* wejones@megalink.net             *
* http://www.megalink.net/~wejones *
************************************
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