The number of satellites in Earth orbit has exploded in recent years. With the rise of megaconstellations, like SpaceX’s Starlink, their disintegration in the atmosphere could have major consequences for Earth’s climate. A study published on October 3, 2024 in the journal Scientific Data, in which researchers from University College London (UCL) took part, highlights the potential effects of this phenomenon.
The process of disintegration of satellites, especially when they burn up at high altitudes, generates metallic particles that enter the stratosphere and mesosphere, experts explain. These particles can have a direct impact on the chemical composition of the air, in particular by contributing to the degradation of the ozone layer.
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Chemical reactions (partly) responsible for the degradation of the ozone layer
The conclusions of this study tell us that particles resulting from combustion, mainly alumina (aluminum oxide), can alter the thermal balance of the atmosphere. Indeed, alumina reflects sunlight, which could ultimately cause warming of the upper layers of the atmosphere.
“We observed gradual warming in the upper layers, with cascading effects that change the chemical composition of the airexplains Connor Barker, researcher in chemical modeling at UCL and author of the study, cited in an article in the MIT Technology Review. These particles can also interact with ozone and gases in the stratosphere, increasing the likelihood of long-term ozone depletion.” These particles remain in the atmosphere for decades or even centuries.
Scientists are warning that warming in the upper layers of the atmosphere could cause a change in the distribution of humidity, another factor likely to compromise the integrity of the ozone layer.
They also inform us that the chemical reactions triggered by the return of satellites into the atmosphere produce nitrogen oxides, which are responsible for part of the degradation of the ozone layer. About 50% of the ozone loss associated with the disintegration of satellites and rocket launches comes from nitrogen oxides.
Major climate changes are to be feared
The environmental impact of satellites is not limited to the ozone layer alone. Simulations carried out as part of the study showed that these phenomena could contribute to major climate changes in the long term. Researchers fear that the amount of metal residue sent into the atmosphere will increase considerably as megaconstellations multiply. By 2033, the number of vaporized space debris could reach 4,000 tonnes per year, ten times more than today.
“The real challenge lies in the uncertainty surrounding the magnitude of these effects”continues Connor Barker. Although the contribution of satellites to air pollution is still small (around 0.1% of current ozone depletion), their impact could grow significantly in the coming decades, depending on the increase in the number of satellites. and the frequency of their returns to the atmosphere.
This study sheds light on the urgency of more rigorous management of end-of-life satellites. If controlled disintegration in the atmosphere remains the preferred means of avoiding the accumulation of debris in space, the environmental consequences of this practice will have to be taken into account in a more systematic manner.
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