Speaker
Description
As part of the ESA-funded Atmospheric Re-entry Assessment (ARA) project (2016 to 2019) we assessed the long-term atmospheric and radiative effects of spacecraft re-entries using detailed global emission inventories for two spacecraft re-entry scenarios (a nominal and a high emission scenarios) in a state-of-the-art global climate model. The spacecraft re-entries cause ozone depletion in the upper stratosphere and in the polar mesosphere due to NO$_{x}$ emissions and heterogeneous reactions on Al$_{2}$O$_{3}$ and TiO$_{2}$ particles. However, the change in ozone is only $−$2.1$\times$10$^{-5}$ % (high emission scenario), which is a factor of 800 smaller than that of historical rocket launchers. Furthermore, we estimate a global mean near-surface temperature change by using the non-linear climate−chemistry response model AirClim, assuming constant spacecraft re-entry frequencies for each scenario between 2017 and 2100. The re-entries cause global warming of climate mainly through changes of ozone and through H$_{2}$O emission, but the calculated surface temperature change amounts to only 220$\times$10$^{-9}$ K for the high emission scenario. Overall, the warming calculated for our re-entry scenarios is much smaller than that caused by other anthropogenic emission sources such as rocket launchers and aviation given the much lower relative emission strength in our re-entry scenarios. Many challenges are remaining related to assessing the atmospheric and climate effects of space transport. Thus, we discuss open issues for chemistry−climate modelling and emission datasets related to space transport.
