Global Climate Effect from Space Debris Reentry: Engineering and Policy Implications

Space objects are routinely reentered into Earth’s atmosphere for disposal. During reentry, space objects demise and produce ablation by-products, including alumina ([Formula: see text]) particles that can interact with Earth’s radiative balance, and possibly influence climate change. In this work, we model a future reentry scenario with [Formula: see text] of alumina entering into the South Pacific from controlled reentries to estimate the implications of a hypothetical policy that requires all reentries to demise over this region. We find that reentry alumina particles remain aloft in the atmosphere for 714 days, generating a direct radiative cooling effect of [Formula: see text] at the top of the atmosphere and [Formula: see text] at the tropopause. These South Pacific reentries create a concentration of particles in the southern stratosphere, leading to asymmetrical radiative forcing. When compared to aviation, the direct radiative forcing from a single reentry is greater in magnitude than a single commercial airliner flight, but reentries as a whole produce less radiative forcing per dollar of industry revenue than commercial aviation. These results support policies that encourage satellite design for demise and reentry as a form of decommissioning but warn against limiting reentry to the South Pacific only.