Effects of launch vehicle emissions in the stratosphere

A plume dispersion and chemical kinetic model has been used to estimate the total impart of motors of different propellant types on stratospheric ozone. In precious studies, industry standard rocket motor performance and plume flowfield computer programs were used to model the chemistry in the rocket combustion chamber and expansion nozzle and also in the downstream afterburning region of the plume. Our model and the results of previous studies were used to follow the plume chemistry for up to a day as the plume dispersed into the ambient stratosphere. Several large motor-types were analyzed: two different solid-fueled motors without chlorine and one with chlorine, an amine/N2O4 fueled first stage, a kerosene/liquid oxygen (LOX) fueled first stage, and an l-H-2/LOX fueled engine with two nozzle variants. The modeled motors are based loosely on existing vehicles, but we varied several parameters to create hypothetical vehicles that may be viewed as prototypes of next-generation launchers. Two dispersion rates were used, a worst case and a best guess, based on published models. In the worst case, ozone depletion due to NOx or other exhaust species was several orders of magnitude smaller than depletion due to chlorine in the exhaust. Depletion due to motors using LOX was minimal within 5 min of vehicle passage in all cases.