Ozone threat from De-orbiting Satellites

The nearly 10,000 LEO satellites will eventually fall back toward the atmosphere or will be deliberately de-orbited as part of their disposal strategy to burn up on re-entry. On entering the atmosphere, satellites leave behind a trail of tiny particles of aluminum oxide that a recent study has found to have significant consequences for the ozone layer of the stratosphere.

The potential for significant damage comes as a recent United Nations assessment revealed that 99% of ozone-depleting chemicals have been phased out since the 1980s and the ozone layer is on track for a full recovery by 2066.

Up 30% of a typical satellite’s 250-kg mass is aluminum, which during a typical re-entry will generate about 30 kg of aluminum oxide nanoparticles. Researchers at the University of Southern California found that re-entering satellites between 2016 and 2022 have increased the amount of aluminum in the atmosphere by 29.5% over natural levels. By the time all planned LEO constellations have de-orbited, around 397 tons of aluminum oxide will have fallen to the ozone layer, an increase of 646% over natural levels.