There was a paper published in June in the peer-reviewed Geophysical Research Letters titled Potential Ozone Depletion from Satellite Demise During Atmospheric Reentry in the Era of Mega-Constellations.
As can be deduced by the lengthy title, the scientists have uncovered a new risk coming from the reentry of low-orbit satellites through the atmosphere. Scientists at the University of Southern California Department of Astronautical Engineering are reporting the increased risk to the ozone layer by the upcoming massive increase in the number of satellites that will be returning to earth each year.
Low-orbit satellites contain a lot of aluminum, and when a satellite falls to Earth it creates aluminum oxide, which results in a chemical reaction that kills ozone. The issue doesn’t just arise at the time that a satellite falls to Earth, because the aluminum oxide particles can linger for up to five years as the particles slowly fall out of orbit.
This is a serious problem…
Depletion of the ozone layer is a serious problem, and a complete destruction of ozone would end most life on the planet since the ozone protects us from cosmic radiation and ultraviolet light coming from the sun. Even a partial depletion means increased skin cancers, cataracts, and damage to marine organisms, plants, and plastics. The planet has come a long way towards stopping depletion of the ozone layer with the Montreal Protocol in 1989 that phased out CFCs and other chemicals that deplete ozone. This treaty resulted in reducing harmful chemicals by 95%. In 2013, scientists predicted that we were a few decades away from the full recovery of the ozone layer.
This issue points out that there are often unintended consequences from any major deployment of a new technology. It’s impossible to deny the huge benefits of low-orbit satellites, and it seems likely that nobody saw this coming. This is obviously an issue that must be addressed, now that the problem has been identified. Perhaps it will be as simple as reducing or eliminating aluminum from low-orbit satellites. But the time to fix this is before there are tens of thousands of satellites in orbit.