Starlink & Co.: Crashing satellites pose a major threat to the ozone layer
The number of satellites is increasing rapidly and this is set to accelerate. This could pose a threat to the ozone layer, warns a research team.
(Image: muratart/Shutterstock.com)
Satellite constellations such as SpaceX's Starlink could jeopardize the recovery of the ozone layer and cause ozone depletion in the stratosphere over decades. This has been determined by a US research group, which explains that the danger comes from the crashing satellites. They are already leaving behind more and more aluminum oxide, which is directly responsible for the depletion of the ozone layer. However, because the particles merely trigger the harmful reactions in the atmosphere and remain intact, this is a persistent danger that jeopardizes the successes achieved in protecting the ozone layer. Between 2016 and 2022 alone, the amount of dangerous oxides in the atmospheric layers increased eightfold.
More and more satellites crashing much faster
The mega-constellations of thousands of satellites are dangerous for two reasons: Firstly, they ensure that there are many more artificial objects orbiting the Earth than has ever been the case - Starlink alone currently accounts for around 6000 of 8100 active satellites. Secondly, the satellites that are supposed to provide the earth's surface with low-latency, high-speed internet connections orbit at a much lower altitude and therefore remain in orbit for a much shorter period of time. This means that the much larger number of satellites crash and burn up in the atmosphere much more quickly than was previously the case. To determine the consequences, the research team led by José Ferreira from the University of Southern California has investigated the effects of the crashes at a molecular level.
As the research group explains, the aluminum oxide particles that remain after the satellites burn up do not react directly with the ozone. Instead, they trigger reactions between ozone and chlorine, which deplete the ozone layer. Because the aluminum oxide is not used up in the process, it can remain in the atmosphere and continue to do so for decades as it drifts through the stratosphere. In addition, the aluminum oxide does not appear in the stratosphere immediately after burning up, but is formed further up in the mesosphere. It would take up to 30 years for it to reach the stratosphere. The depletion of the ozone layer would therefore only begin once the mega-constellations have been in space for a long time and would then be a long-term problem.
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Considering the plans for mega-constellations consisting of several thousand satellites each, the aluminum used in them could jeopardize the successes in the fight to preserve the ozone layer, according to the research group. It found that by 2022, the amount of aluminum in the atmosphere was already almost a third above the natural level. If the current satellite plans are implemented, the more than 900 tons of aluminum that fall over the earth every year could cause 360 tons of aluminum oxide to be released into the atmosphere each year. This would be more than six times the natural amount and could significantly deplete the ozone layer. The work is presented in the scientific journal Geophysical Research Letters.
Because the ozone layer is a particularly important protection for life on Earth, changes to it could have drastic consequences in the worst-case scenario. The emission of chlorofluorocarbons (CFCs) first put it at risk at the end of the last century, but thanks to international cooperation it was possible to take action against this and the measures taken subsequently are now showing results. While research into the consequences of the new space age has so far been limited to rocket launches, the new work shows that satellites themselves also pose a threat. At the same time, it is not the first warning of possible unforeseen consequences of Starlink.
Not the first unforeseen danger
SpaceX has been building Starlink since 2019, and the thousands of satellites now provide fast internet connections on all continents. In the future, 30,000 satellites will allegedly connect regions where conventional technology is not economically viable. Companies such as Amazon are also planning their own mega constellations. Initially, there was criticism of the light pollution caused by the many satellites passing through the sky. However, SpaceX has already promised to reduce this interference, and the satellites should at least no longer be visible to the naked eye. It was later revealed that the Starlink antennas could even interfere with weather forecasts.
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(mho)