Thousands of satellites are currently parked in low Earth orbit, some of which will eventually become defunct and fall back into our planet’s atmosphere. When satellites re-enter the atmosphere, they leave behind a trail of chemicals that eat away at the ozone layer. A new study warns against the growing number of internet satellites that have contributed to a shocking eightfold increase in harmful oxides in the Earth’s atmosphere over a six-year period.
Not all satellites are created equal. Internet satellites typically have a shorter lifespan of about five years, after which they are deorbits and plummets toward Earth’s atmosphere. Of the nearly 10,000 satellites in orbit today, two-thirds belong to SpaceX’s broadband constellation, Starlink.
SpaceX has launched more than 6,000 Starlink satellites into orbit, and the company’s billionaire founder Elon Musk hopes to build a massive constellation of 42,000 satellites. SpaceX isn’t the only company building a constellation in low Earth orbit. Blue Origin’s Kuiper Project also plans to send 3,000 satellites into space, while Europe’s OneWeb wants to build a constellation of 648 satellites. These figures give us great anxiety about Kessler’s syndrome.
Related article: What you need to know about Kessler syndrome, the ultimate space disaster
Besides the increased risk of collision, Internet satellites are in more frequent rotation than their longer-lived counterparts, with companies repeatedly releasing replacements to support their broadband services. At the end of their short lives, satellites generate pollutants as they fall through the atmosphere. Satellite reentry produces tiny particles of aluminum oxide that trigger chemical reactions that destroy stratospheric ozone, according to a recent study published in Geophysical Research Letters. The oxides do not react chemically with the molecules of the ozone layer; instead, they cause destructive reactions between ozone and chlorine that eventually deplete the protective layer in Earth’s atmosphere.
“It’s only in recent years that people have started to think that this might become a problem,” said Joseph Wang, an astronautics researcher at the University of Southern California and lead author of the new study. statement. “We were one of the first teams to look at what the significance of these facts might be.”
Using a model of the chemical composition of the material used to build satellites, the researchers found that a typical 550-pound (250-kilogram) satellite, with aluminum making up 30 percent of its mass, would generate about 66 pounds (30 kilograms) of nanoparticles of aluminum oxide (1 to 100 nanometers in size) during its re-entry. Based on this modeling, the study found that satellite re-entry increased the amount of aluminum in the atmosphere by 29.5% over natural levels from 2016 to 2022.
It only gets worse from here. According to the study, it would take about 30 years for the aluminum oxide particles to descend to the same altitude as the Earth’s stratosphere, where 90% of the ozone is found. By the time the planned Internet constellations are built in low Earth orbit, 1,005 tons of aluminum will fall into Earth’s stratosphere. This would release about 397 tonnes of aluminum oxides annually into the atmosphere, a 646% increase over natural levels.
Just when things started looking up for Earth’s ozone layer. A recent assessment of the United Nations Environment Program revealed that the ozone layer is on track to be fully recovered by 2066. Nearly 99% of ozone-depleting chemicals have been phased out since the 1980s thanks to an international treaty to protect our ozone signed in 1987.
The recent study underscores the need for better regulations to help mitigate the effects of a growing space industry — one that likes to deploy satellites all around Earth.
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