Why the constellation of Starlink satellites threatens the ozone layer

The burning of end-of-life satellites and rocket fuel could create a new hole in the ozone layer and disrupt the global climate. In question: These thousands of satellites contain large amounts of aluminum.

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[EN VIDÉO] How many satellites revolve around the earth?
According to the UCS (Union of Concerned Scientists) Association there were 2,787 satellites operational as of December 31, 2020, of which more than half were launched by the United States. Three-quarters of the satellites in operation orbit in low orbit (between 500 and 2,000 km altitude), and are used for telecommunications systems, terrestrial imagery or meteorology.

already accused light pollution or increase collision hazard, satellites of the constellation starlink Now suspected of causing “climate catastrophe”. Alert was started by Aaron Bole, co-teacher astronomy andastrophysics at the University of British Columbia, in a study published in scientific report, last May. The reason for his concern:aluminum Materials in satellites that can polluteAtmosphere When consumed during deorbitation. Starlink’s 12,000 satellites” Will cause the arrival of 2 tons of material per day in the Earth’s atmosphere. This is far less than the 54 tons of meteorites that come daily, but contain only 1% aluminium. », underlines the researcher.

A new hole in the ozone layer?

However, aluminum produces alumina, or aluminum oxide, when combustion. and previous studies have shown that fuel containingLess likely to be poor ozone layer. « 1,000. emissions resulting from the launch of rockets Suborbital can reduce ozone density in the highlands by 5-6% per year latitudes, which is equal to the effect of CFC [les chlorofluorocarbones interdits par la protocole de Montréal en 2006, ndlr] », warns Martin Ross, in the Journal of the Aerospace Corporation Geophysical Research Papers. Typically, satellites burn up in the upper layers of the atmosphere: between 50 and 90 km, or more ozone layer Which extends from 10 to 60 km. ” But the particles will eventually sink to the lower layers. », confirms Gerhard Drolshagen from the University of Oldenburg in Germany, questioned by Space.com.

A giant experiment in uncontrolled geoengineering

And this isn’t the only climate catastrophe that is likely to happen to all of these satellites at the end of their lives. ” shows alumina Light at certain wavelengths, and if you release enough of it into the atmosphere, you’ll changealbedo of planet », with a guard Aaron said. Injection of alumina is also one of the means considered cool the climate as part of’Geoengineering Experiments. except that here,” It is an experiment without any oversight or regulation […] We don’t know what the thresholds are and how it will affect the upper atmosphere », adds the researcher.

US telecommunications operator Viasat also cited concerns about the effects of aluminum oxide on the atmosphere during its request. Federal Communications Commission (FCC) SpaceX to postpone the launch of the mega-constellation Starlink until a proper environmental review of its potential impacts is completed. ” These changes can increase the risk of harm to health and the environment to unacceptable levels. » writes Viasat.

Spread of end-of-life satellites

« Humans are exceptionally good at underestimating their ability to disrupt the environmenthorrified, paradoxically, said Aaron spread of these constellations. In two years, the number of active and dead satellites in the lower atmosphere has increased by more than 50%, to reach nearly 5,000 by March 30, 2021. SpaceX alone is on track to add 11,000 more and has already submitted an authorization request. 30,000 others with the FCC “. One possible solution would be to replace aluminum in rockets and satellites with another material. But which one? Aluminum is very light and melts very well during atmospheric re-entry. Using stronger materials will increase the risk of debris falling to the ground. A real puzzle!

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