Duration: 9 months
The re-entry rate of space debris (spent rocket motors and defunct satellites) is already comparable in mass terms to the natural cosmic dust input. The ablation of some metals – Al, Li, Cu, Nb, Ag – from this debris is now the dominant input, which is likely to grow rapidly over the next decades due to the projected increase in space-based assets with limited orbital lifetimes. The purpose of this project will be to quantify – for the first time - impacts on the stratospheric ozone layer caused by the injection of alumina particles produced from space debris ablating above 60 km. These impacts will include the surface-catalyzed photolysis of hydrogen chloride (the major chlorine reservoir), and increased freezing of polar stratospheric clouds: both of which would enhance ozone destruction, changing the radiative balance of the atmosphere and increasing harmful UV light at the surface. We will use a new version of the Community Aerosol and Radiation Model for Atmospheres (CARMA) model implemented within the Whole Atmosphere Community Climate Model (WACCM), to simulate the injection of alumina particles from space debris ablation, and their subsequent transport and interactions with sulfuric acid and meteoric smoke particles in the stratosphere; and hence model the potentially important impacts of these particles on chemistry and related atmospheric dynamics and climate. We will work closely with Juan Carlos Gómez Martín (IAA-CSIC, Granada), who will be funded through an OSIP to study experimentally the ablation of space debris materials. In the current absence of experimental data for some physico-chemical parameters related to alumina (e.g. uptake coefficients and photochemical quantum yields), our modelling work will involve sensitivity studies of these parameters, along with the magnitude and location of ablation. The resulting scoping study will be invaluable for planning future experimental work and contextualizing the scale of the environmental problem.
