Scientists are keeping a close eye on the possible effects of Earth’s orbital congestion on our atmosphere. The effects of aluminum oxide particles left over from the burn-up of former satellites are clarified by a recent study. According to the research team, there has been an eight-fold rise in these oxides between 2016 and 2022.
As the quantity of satellites in low-Earth orbit keeps increasing at a rapid pace, the issue is predicted to get worse. Researchers predict that aluminum oxide in orbit has increased by 646% beyond its natural levels. Through the regulation of chlorofluorocarbons (CFCs), the 1987 Montreal Protocol effectively solved the ozone depletion catastrophe. The detritus from defunct satellites, however, presents a fresh danger to the ozone layer’s recuperation.
Constellations of internet satellites are clogging Earth’s orbit more and more. Usually, these satellites spend five years or more in orbit. When their time is up, they burn up and leave behind aluminum oxide particles in the Earth’s atmosphere. The cycle is then completed when these satellites are replaced with new ones that will burn up in five years.
SpaceX’s Starlink satellites make up the majority of objects in low Earth orbit. There are currently about 6,000 SpaceX satellites orbiting Earth. The company has permission to launch another 12,000, and it aims to eventually send as many as 42,000 to LEO. Other companies like Amazon, with its Project Kuiper, are also looking to send thousands of internet satellites to space.
Scientists from the University of Southern California, Los Angeles, point out that aluminum oxides spark chemical reactions that destroy stratospheric ozone, potentially widening holes in the ozone layer. The researchers published their findings in Geophysical Research Letters, stating that aluminum oxides trigger destructive reactions between ozone and chlorine.
Furthermore, aluminum oxides are not consumed by these chemical reactions, meaning they will continuously destroy ozone molecules as they drift down towards Earth. According to researchers, the oxides can stay in Earth’s atmosphere for decades. This means the trend of sending satellites to LEO to be burned up in five-year cycles could have a cumulative destructive effect.
Joseph Wang, an astronautics researcher at the University of Southern California, explained that only in recent years have people started to think this might become a problem. The scientists used computer models to estimate the effects of satellites burning up on reentry. In 2022, aluminum in the atmosphere increased by 29.5% over natural levels due to satellite reentries.
Their models indicate it would take roughly thirty years for aluminum oxide particles to drift down to stratospheric levels, where most ozone molecules are located. They estimated that based on current trends, we will eventually see 397 tons of aluminum oxide particles falling to Earth yearly, a 646% increase over natural levels, based on the scenario that all currently planned satellites will fly to LEO.
