>| Space shuttle exhaust is simply water vapor.  They are combining
>| hydrogen with oxygen to get water.

        The solid rocket booster's do burn some aliminum based compound
if memory serves me correctly. The shuttle itself, produces steam and maybe
a bit of nitrogen oxides which form around the edges of the exhuast jet
as that should be quite hot (though I don't know if the same conditions that
make nitrogen oxdies form in an enclosed space would be present on the
edge of the exhaust jet)...

dave