The impact of the spacecraft system Saenger on the composition of the middle atmosphere

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A two-dimensional chemical model and physical considerations are used to estimate the impact of the spacecraft system SANGER on stratospheric and mesospheric ozone in relation to other spacecraft and other anthropogenic perturbations. Perturbations of middle atmospheric NO,, H,O and H2 concentrations, and their impact on the radiative balance of the atmosphere, including contrail formation, are discussed. It is found, that in case of about 24 launches per year the perturbations due to S U G E R are about negligible on a global scale. However, if a S U G E R version would be used for a hypersonic fleet of commercial aircraft a serious ozone depletion is predicted. W THE SPACECRAFT SYSTEM SANGER The concept of the spacecraft system S m G E R is, that it can take off and land like an aeroplane. It consists of a lower and upper stage. In contrast to existing spacecraft systems the engines of the lower stage use ambient air for combustion like conventional airplanes. The he1 is liquid hydrogen. The spacecraft system has no solid fuel boosters. The mission of the lower stage can be divided in 5 typical phases: take off at airbases in Europe and ascent to lower stratosphere in turbojet mode; ascent from 19.6 km to 26 km in ramjet mode; cruise at 26 km to about 20” latitude in ramjet mode: further ascent to 34.6 km and acceleCopyright 1992 by Wax Planck Society. Published by the American Institute of Aeronautics and Astronautics, h c . with permission. ration to Mach 6.5 with release of the upper stage to orbit; return cruise to Europe in ramjet-mode at about 26 km altitude. The typical flight patterns are given in Fig. 1. The engine of the upper stage is fueled by liquid hydrogen and oxygen. It has a thrust of 1400 kN and bums from 34.6 km to 70 km altitude, the perigeum of its first orbit. After reentry, the upper stage returns to the surface in a similar way as the space shuttle.