Burning up of satellites severely harms ozone recovery

The rapid expansion of satellite “megaconstellations” is jeopardizing the recovery of the ozone hole.

As satellites fall into Earth’s atmosphere and burn up, they release tiny particles of aluminum oxide. These particles can severely damage Earth’s protective ozone layer.

A recent study revealed that aluminum oxides increased eight-fold between 2016 and 2022, with more accumulation expected as the number of low-Earth-orbit satellites continues to rise.

Satellite megaconstellations

Megaconstellations are large groups of low Earth orbit satellites working together for global coverage. Companies like SpaceX and Amazon lead this effort, aiming to provide high-speed internet worldwide. Starlink, SpaceX’s project, plans up to 42,000 satellites.

Amazon’s Project Kuiper will launch thousands more. These satellites orbit closer to Earth, reducing signal delay and improving internet access in remote areas.

However, megaconstellations pose environmental and space traffic risks. When satellites re-enter the atmosphere, they release aluminum oxides, threatening the ozone layer.

The rapid increase in satellite numbers raises concerns about space debris, which can cause collisions and damage other satellites.

Despite these challenges, megaconstellations represent a significant technological advance, potentially revolutionizing global communication. Balancing their benefits with environmental and safety considerations is crucial for sustainable space development.

Shrinking ozone hole

The 1987 Montreal Protocol successfully regulated ozone-depleting chlorofluorocarbons (CFCs), resulting in a shrinking ozone hole over Antarctica.

Full recovery was anticipated within fifty years. However, the unexpected rise in aluminum oxides may halt this progress in the coming decades.

Proliferation of low-earth-orbit satellites

Currently, there are 8,100 objects in low Earth orbit, with 6,000 of them being Starlink satellites that were recently launched.

The demand for global internet coverage drives the rapid increase in the number of small communication satellites.

SpaceX leads this effort, with permission to launch another 12,000 Starlink satellites and plans for up to 42,000 in total.

Companies like Amazon are also planning constellations ranging from 3,000 to 13,000 satellites.

Ozone threat from satellite lifespans

Internet satellites in low Earth orbit have a short lifespan of about five years. To maintain internet service, companies must continually launch replacement satellites, perpetuating a cycle of planned obsolescence and unplanned pollution.

Aluminum oxides from these satellites trigger destructive reactions between ozone and chlorine, depleting the ozone layer.

These oxides persist in the atmosphere for decades, continually destroying ozone molecules.

Lack of attention to satellite pollutants

Despite the potential damage, little attention has been paid to pollutants formed when satellites burn up in the upper atmosphere.

Previous studies focused on the consequences of launching vehicles into space, such as the release of rocket fuel.

The new study by researchers from the University of Southern California Viterbi School of Engineering provides the first realistic estimate of the extent of long-lived pollution in the upper atmosphere.

Satellite pollution and ozone damage

“Only in recent years have people started to think this might become a problem,” said Joseph Wang, a researcher in astronautics at the University of Southern California and corresponding author of the study. “We were one of the first teams to look at what the implication of these facts might be.”

The experts used advanced modeling to estimate pollution from satellite re-entry. Previous estimates based on micrometeoroids were inaccurate due to the low aluminum content in micrometeoroids compared to satellites.

Ozone depletion and satellite re-entry

In 2022, re-entering satellites increased atmospheric aluminum by 29.5% over natural levels.

The study found that a typical 250-kilogram satellite, with 30% of its mass as aluminum, generates about 30 kilograms of aluminum oxide nanoparticles during re-entry.

Most of these particles are created in the mesosphere, 50-85 kilometers above Earth’s surface.

The researchers estimate that it will take up to 30 years for these particles to drift down to the stratosphere, where 90% of Earth’s ozone is located.

By the time the planned satellite constellations are complete, approximately 912 metric tons of aluminum will fall to Earth annually, releasing around 360 metric tons of aluminum oxides each year, a 646% increase over natural levels.

Ozone layer recovery at risk

The rapid expansion of satellite megaconstellations poses a significant threat to the recovery of the ozone layer.

Immediate attention and further research are crucial to mitigate this emerging environmental challenge and ensure the continued protection of Earth’s ozone layer.

The study is published in the journal Geophysical Research Letters.

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