MadSci Network: Environment/Ecology

Re: Does the solid rocket fuel that NASA uses depleat the Ozone Layer?

Area: Environment/Ecology
Posted By: David Ellis, Researcher, NASA Lewis Research Center
Date: Tue May 6 09:11:28 1997
Area of science: Environment/Ecology
ID: 861841970.En

NASA uses several catagories of rocket engines and fuels. Among them are:

The ozone layer is normally depleted by halogen (F, Cl, Br, I, At) containing gases. The liquid fuel rockets fueled with hydrocarbons such as kerosene produce essentially the same products as your car engine; CO, CO2, H2O. Because of the method of burning the fuel and the extremely high temperatures involved, the chemical reaction tends towards completion, and the main products are CO2 and H2O. The hydrogen fueled rockets are even cleaner with the only combustion product being H2O. Hypergolic rockets can use chemicals containing halogens, but they are very small rockets used in space for steering and small corrections to the flight path. They are used above the atmosphere and should not contribute anything to ozone depletion.

For solid fuel rockets, the "Other" class contains a variaty of fuels. Most NASA rockets, as opposed to the large Air Force and Navy rockets, are liquid fueled. One of the main uses for the solid fuel rocket is as a booster for satellites placed into orbit by the space shuttle. There the products of the chemical reaction are high above the Earth's atmosphere and should not have any significant effect. There really is not a significant use of solid fueled rockets beyond that at NASA other than the space shuttle.

The Solid Rocket Boosters or SRBs used in the space shuttle are probably the only NASA rocket that could contribute anything significant to ozone depletion. One of the components of the SRB fuel is ammonium chloride. The resulting gas formed during combustion could deplete the ozone. However, consider the frequency and amount of ozone depleting gases produced. NASA is typically flying 8 shuttle missions per year. In addition, Stennis Space Center test fires a few SRBs a year. While there is considerable smoke and flame, the total amount of ozone depleting gases is fairly minimal compared to the other sources such as leaking chlorinated fluorocarbon (CFC) refrigerant. As such, the ozone depletion from NASA space missions has to be considered minimal.

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