and 0.1% in the altitude range of 30 to 40 km and less at lower altitudes. Most of the ozone in the atmosphere is located between about 23 and 35 km. These water vapor injections are unlikely to have any direct effect on the ozone content as a whole. However, they will be concentrated in an area above the launch site, and the consequences of this localization should be explored. TABLE 30 SHUTTLE VEHICLE WATER VAPOR INJECTION INTO THE STRATOSPHERE The percentage increment in water vapor is large in the highest region of the stratosphere near 50 km, due to the fact that the atmosphere is extremely thin and consequently its total'water content is low, even though the mixing ratio is about twice that observed at lower levels. The chemistry of water vapor in the upper stratosphere has been studied but there is great uncertainty regarding the possible consequences of increments in water vapor on the order of 10%. Water vapor is photodissociated to form hydrogen, hydroxyl, and hydroperoxyl radicals and hydrogen peroxide molecules which will react with ozone, and molecular and atomic oxygen. The latter constituent is abundant at this level. Since some of the NOX at lower levels is produced in the mesosphere and carried downward through the region in question, it is conceivable that changes in the water vapor content will influence the natural flux of NOX to the level of the ozone layer. Consequently, the effects of shuttle flight water vapor injection in the region of 40 to 50 km should receive further study. Booster engines using solid fuel are also employed during the first two minutes after launch. These consume a total of 3x 1 O' 6 pounds of fuel per launch, of which 4x 10s pounds consist of CO, HC1, and NO. We have been unable to obtain information regarding the chemical form of the remaining exhaust products. Even if all of it is water, it is unlikely that there will be any adverse effect on the stratosphere due to water vapor pollution. According to Martell (55), vertical eddy mixing is very rapid throughout the mesosphere (50 to 80 km) and the lower thermosphere (80 to 100 km) and for this reason the effect of water vapor emissions in these regions has not been calculated. The region of the atmosphere from the stratopause to 100 km in altitude contains only 0.1% of the total mass of the atmosphere, or about 5x18* 8 grams. The annual injection of water vapor into this region will be about 12xl09 gms. Injection of water and other exhaust products will, of course, be very localized, so that large increases in the abundance of water vapor will be expected in the very small region near the launch
RkJQdWJsaXNoZXIy MTU5NjU0Mg==