Thousands of satellites are currently parked in low Earth orbit, with some that will eventually become defunct and fall back towards our planet’s atmosphere. As they reenter the atmosphere, satellites leave behind a trail of chemicals that eat away at the ozone layer. A new study warns against the growing number of internet satellites, which have contributed to a shocking eight-fold increase of harmful oxides in Earth’s atmosphere over a span of six years.
Not all satellites are created equal. Internet satellites tend to have a shorter lifespan of around five years, after which they aredeorbited and plummet toward Earth’s atmosphere. Out 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 to orbit, and the company’s billionaire founder Elon Musk is hoping 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 Project Kuiper also plans to send 3,000 satellites to space, while Europe’s OneWeb wants to build a constellation of 648 satellites. Those numbers are giving us major Kessler Syndrome anxiety.
Related article: What to Know About Kessler Syndrome, the Ultimate Space Disaster
Aside from the increasing risk of collision, internet satellites are in a more frequent rotation than their more long-lasting counterparts, with companies repeatedly launching replacements to maintain their broadband services. At the end of their short lifespan, the satellites generate pollutants as they fall through the atmosphere. Satellite reentry produces tiny particles of aluminum oxide, which trigger chemical reactions that destroy the stratospheric ozone, according to the recent study published in Geophysical Research Letters. The oxides don’t react chemically with the molecules of the ozone layer; instead they set off destructive reactions between ozone and chlorine that end up depleting the protective layer in Earth’s atmosphere.
“Only in recent years have people started to think this might become a problem,” Joseph Wang, a researcher in astronautics at the University of Southern California and lead author of the new study, said in a statement. “We were one of the first teams to look at what the implication 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% of its mass, will generate about 66 pounds (30 kilograms) of aluminum oxide nanoparticles (1 to 100 nanometers in size) during its reentry plunge. Based on that modeling, the study revealed that reentering satellites increased the amount of aluminum in the atmosphere by 29.5% over natural levels from 2016 to 2022.
It only gets worse from here. It would take about 30 years for the particles of the aluminum oxides to drift down to the same altitude as Earth’s stratosphere, where 90% of the ozone is located, according to the study. By the time the planned internet constellations have been built in low Earth orbit, 1,005 tons of aluminum will have fallen to Earth’s stratosphere. That will release around 397 tons of aluminum oxides per year to the atmosphere, an increase of 646% over natural levels.
Just when things were starting to look up for Earth’s ozone layer. A recent assessment from the United Nations environment program revealed that the ozone layer is on track for a full recovery by 2066. Nearly 99% of ozone-depleting chemicals have been phased out since the 1980’s thanks to an international treaty to protect our ozone signed in 1987.
The recent study highlights the need for better regulations to be put in place to help mitigate the effects of a growing space industry—one that loves putting satellites all around the Earth.
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