28 June 2024

Humanity's satellite habit could end up choking Earth's ozone layer


Large numbers of low Earth orbit satellites such as those operated by Starlink could pose a threat to the planet's ozone layer once they re-enter the atmosphere, according to recent research.

Constellations of small satellites being deployed for purposes such as broadband coverage typically have a relatively short life span, said to be about five years for Starlink, after which they re-enter the atmosphere and burn up, with replacements sent up to take over their roles.

But researchers at the University of Southern California (USC) say that this leads to the generation of aluminum oxides in the atmosphere, which are known to accelerate ozone depletion. The large number of satellites involved – Starlink alone was estimated to have 6,078 satellites in orbit as of May 2024 – could mean this presents a serious risk.

A research letter published in Geophysical Research Letters, "Potential ozone depletion from satellite demise during atmospheric re-entry in the era of mega‐constellations," says the demise of a typical 250 kg satellite can generate around 30 kg of aluminum oxide nanoparticles, which may endure in the atmosphere for decades.

The researchers calculate that large constellations of satellites may cause over 360 metric tons of aluminum oxide compounds to enter the atmosphere per year, which could lead to significant ozone depletion.

Aluminum is one of the most common materials in satellites, the article says, and reacts with oxygen upon re-entry in the atmosphere to generate aluminum oxide that can interfere with ozone chemistry. A chlorine activation reaction catalyzed on the surface of aluminum oxide particles boosts ozone depletion.


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