Hydrazine combustion in space?

[edtman]

Hi,
I know this is a chemistry question but I was hoping there'd be a kind soul with a chemistry background whose willing to help!
The space research group I work for has 2 satellites which have hydrazine (N2H4) monopropellant thrusters. From what I understand the pressurized hydrazine is sprayed through ab iridium heating bed where it reacts and breaks down into ammonia and nitrogen. I am told that this reaction will occur without the iridium heating beds.
My question is what induces the reaction? My chemistry is rusty, but I know heat can cause chemical reactions, and the ideal gas law show that heat and pressure are proportional...so is reducing the pressure analogous to reducing heat? And if so why will adding heat to the system through iridium heat beds speed up the reaction? Is it common for chemicals under pressure to react when released in vacuum. Thanks for your time!

Ed

 

[edtman]

To answer my own question...after reading what I wrote and reviewing the good-ol' chemistry text. First of all I meant combustion in the most liberal use of the word, since oxygen and burning is required for true combustion to occur.
What happens is the irridium acts as a catalyst to induce a decomposition reaction of hydrazine. By definition a catalyst changes the speed of a chemical reaction without under going a permanent change itself. And why did it take me so long to figure that out? Vacation make the grey (or is it gray?) matter go mush...