Impact of rocket exhaust plumes on atmospheric composition and climate ― an overview

¹ Deutsches Zentrum für Luft- und Raumfahrt (DLR) Institut für Physik der Atmosphäre Oberpfaffenhofen, Wessling 82234, Germany
² Johannes-Gutenberg-Universität Mainz Institut für Physik der Atmosphäre 21 Johannes-Joachim-Becher-Weg, Mainz 55099, Germany

Abstract

Rockets are the only direct anthropogenic emission sources into the upper atmosphere. Gaseous rocket emissions include CO, N₂, H₂, H₂O, and CO₂, while solid rocket motors (SRM) additionally inject significant amounts of aluminum oxide (Al₂O₃) particles and gaseous chlorine species into the atmosphere. These emissions strongly perturb local atmospheric trace gas and aerosol distributions. Here, previous aircraft measurements in various rocket exhaust plumes including several large space shuttle launch vehicles are compiled. The observed changes of the lower stratospheric composition in the near field are summarized. The injection of chlorine species and particles into the stratosphere can lead to ozone loss in rocket exhaust plumes. Local observations are compared with global model simulations of the effects of rocket emissions on stratospheric ozone concentrations. Large uncertainties remain concerning individual ozone loss reaction rates and the impact of small-scale plume effects on global chemistry. Further, remote sensing data from satellite indicate that rocket exhaust plumes regionally increase iron and water vapor concentrations in the mesosphere potentially leading to the formation of mesospheric clouds at 80- to 90-kilometer altitude. These satellite observations are summarized and the rocket emission inventory is compared with other natural and anthropogenic sources to the stratosphere such as volcanism, meteoritic material, and aviation.