Concentrations of ozone-damaging aluminum oxide in Earth’s atmosphere could rise by 650% in the coming years due to an increase in the number of unused satellites burning up during re-entry, according to a first-of-its-kind study. As mega satellite satellites continue to attract interest from private companies, this could be pretty bad news for our planet’s protective shield known as the ozone layer.
Increasing concentrations of satellite-derived pollutants could cause “potentially significant” ozone depletion, thus hindering the slow and steady recovery of the ozone layer, the study’s authors say.
The ozone layer needs to be repaired first because a hole in this layer opened up over Antarctica in the 1980s due to the use of chlorine and fluorine-rich gases in refrigerants and aerosol sprays. However, this hole is closing thanks to the Montreal Protocol, which banned these disturbing substances in 1987. But if the team’s new study is correct, this healing process may soon face a major obstacle due to a new man-made threat: megaconstellations. In short, megaconstellations are clusters of hundreds (sometimes thousands) of individual satellites working together.
In recent years, Scientists began to express concerns It is about the increasing number of satellites burning in the Earth’s atmosphere. Spacecraft bodies are made of aluminum, which when burned releases aluminum oxides that destroy ozone. The new study, conducted by researchers from the University of Southern California (USC) in Los Angeles, is the first to model the occurrence of these pollutants in the atmosphere and predict the evolution of their concentrations based on the projected proliferation of satellites.
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“This study used atomic-scale molecular dynamics simulation to measure the amount of aluminum oxide produced for reentry into a model satellite and then used the number of reentry satellites planned for satellite megaconstellations to predict the amount of aluminum oxide produced in the future.” Space Sciences at USC. Joseph Wang, professor of Aerospace and Mechanical Engineering and corresponding author of the study, told Space.com.
Researchers found that approximately 332 metric tons of old satellites burned up in the atmosphere in 2022, producing 17 metric tons of aluminum oxide particles in the process. Between 2016 and 2022, atmospheric concentrations of these oxides increased eightfold and will continue to increase further with the increasing number of launched and re-entering satellites.
According to the European Space AgencyThere are currently approximately 12,540 satellites in Earth orbit, of which approximately 9,800 are operational. By the end of this decade, that number could increase tenfold as private companies plan to build mega-constellations of tens of thousands of internet-beaming, low-Earth orbit satellites. SpaceX’s Starlink megaconstellation, for example, currently includes more than 6,000 spacecraft, and the company has plans to deploy up to 40,000 satellites in total for the effort. Companies such as OneWeb, Amazon and Chinese projects G60 and Guowang are developing their own mega-constellations.
If all these plans come to fruition, up to 3,200 metric tons of satellite bodies will burn up in the atmosphere every year until the 2030s. As a result, researchers estimate, 630 metric tons of aluminum oxide could be released into the upper atmosphere annually, leading to an increase of up to 650% in concentrations of these particles compared to natural levels.
The particles, which first accumulate at an altitude of about 50 miles (85 kilometers) where most of the satellite material evaporates, take up to 30 years to reach altitudes where the ozone layer is located, Wang said. Only then would the oxides begin their destructive work. The researchers did not study the effect on the protective ozone shield in detail. But they stressed the effects could be “significant.”
Most of the planet’s protective ozone concentrated in the stratosphere at altitudes between nine and 28 miles (15 and 30 km). Ozone protects living organisms on the planet’s surface from damage by absorbing harmful ultraviolet (UV) radiation.
Unlike traditional ozone-depleting substances, aluminum oxide particles trigger ozone destruction processes without being consumed in reactions, the researchers said. The concentrations of these substances therefore remain constant and the oxides to continue their harmful work until they naturally descend to lower altitudes below the ozone layer. However, Wang said this could also take up to 30 years.
Although much more meteorite material enters the Earth’s atmosphere each year from artificial satellites, this natural space rock does not pose any risk to the ozone layer because it does not contain aluminum. More research is needed to fully understand the risks megaconstellations pose to our planet, the researchers said.
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“The chemistry and physics of these reentry byproducts as they cool and precipitate in the atmosphere, including chemical reactions with ozone, are not the subject of this study and are not fully understood by the public,” José Pedro Ferreira, a research assistant at USC and lead author of the study, told Space.com in an e-mail. -he said in the mail. “Therefore, it is premature to draw any conclusions regarding environmental impacts. These known unknowns should serve as an incentive to devote more resources to this line of research currently being pursued by our group at USC.”
Study It was published June 12 in the journal Geophysical Research Letters.