Starlink: Musk’s satellites threaten the ozone layer

Old satellites destroyed when they fall into the atmosphere release metal particles that threaten to delay the healing of the ozone hole, a new study warns, as Elon Musk’s SpaceX and other companies launch satellites by the thousands.

The study was published in Geophysical Research Letters Aluminum oxide, or alumina, screens nanoparticles released during satellite re-entry into the atmosphere and destroys stratospheric ozone.

The enrichment of the atmosphere with aluminum due to satellite returns has increased eight-fold between 2016 and 2022, according to estimates by researchers at the University of Southern California in Los Angeles.

Of the approximately 10,000 active satellites currently orbiting Earth, 6,000 of them belong to Starlink, the satellite internet service SpaceX has been offering for a few years.

As the demand for such services increases, the number is expected to increase significantly. SpaceX has obtained permission from the US authorities for another 12,000 satellites, with the possibility of reaching 42,000 satellites, while Amazon and other companies are planning their own constellations, consisting of 3 to 13 thousand ships.

Internet satellites travel at a relatively low altitude of up to a few hundred kilometers to provide fast access. But this means that the satellites accept the pull of air molecules and gradually slow down and begin to fall towards the Earth, and their lifespan is limited to about 5 years. This means that the fleet must be constantly renewed.

Emerging threat

The alumina released when it enters the atmosphere does not directly harm ozone, but acts as a catalyst for chemical reactions that destroy this valuable molecule, which protects living organisms from the sun’s dangerous ultraviolet rays.

Thanks to the Montreal Protocol in 1987, emissions of ozone-depleting CFCs have decreased significantly, and the ozone hole over Antarctica is expected to be completely healed within about five decades.

According to the new study, mass launches of satellites could prolong the problem for many decades.

“Only in recent years has it become clear that it could become a problem,” said Joseph Wang, who led the study. “We are one of the first groups to look at the potential impact.”

Since it is practically impossible to directly measure metal contamination from destroyed satellites, the researchers used computer models of the composition and chemical bonds in the materials of a typical 250-kilogram satellite, which is composed of 15 to 40 percent aluminum. Models simulated chemical reactions in the atmosphere to give an estimate of pollution.

Calculations showed that a typical satellite releases about 30 kilograms of alumina nanoparticles.

The study estimates that by 2022 alone, satellite reentries will increase aluminum levels in the atmosphere by 29.5% above natural levels.

These particles are released mainly into the mesosphere, at an altitude of 50-85 km, but remain suspended for decades, and at some point descend into the stratosphere, where most of the ozone in the atmosphere is located.

When the planned constellations of Internet satellites are completed, the atmosphere will be enriched with 360 tons of alumina per year, an amount that would lead to significant ozone losses.

These results are in addition to a previous study conducted in October that found that 10% of sulfuric acid droplets in the stratosphere, which stabilizes the ozone layer, contain aluminum and other metals from spacecraft, which is a new type of pollution that threatens not only the ozone layer, but It also threatens the ozone layer. As well as the global climate.