« on: 12/08/2005 15:45:51 »
Originally posted by Allison
The fuel used to power the space shuttle is super-cooled liquid hydrogen, rather than some kind of petroleum-based fuel. The hydrogen is mixed with liquid oxygen inside the engines (the reaction provides the energy required to blast off), and the clouds of "smoke" that appear when the shuttle blasts of is actually water vapor--incredibly dramatic water vapor, but much less harmful than exhaust from a tail pipe.
Unfortunately, this is only half the story. The three main engines are hydrogen-oxygen powered. The two boosters, that provide ~80% of the lift-off thrust utilize solid fuel. The oxidizer in the Shuttle solids is ammonium perchlorate, which forms 69.93 percent of the mixture. The fuel is a form of powdered aluminum (16 percent), with an iron oxidizer powder (0.07) as a catalyst. The binder that holds the mixture together is polybutadiene acrylic acid acrylonitrile (12.04 percent). In addition, the mixture contains an epoxy-curing agent (1.96 percent). The binder and epoxy also burn as fuel, adding thrust.
As you can see, there are many pollutants available from the SRBs. Once again, the decision to use SRBs was economic. Liquid propulsion was always first choice.
However, Boeing's new Delta IV rocket has an all cryogenic hydrogen-oxygen propulsion system.
"F = ma, E = mc^2, and you can't push a string."