(Photo by MARIANA SUAREZ/AFP via Getty Images)
More and more satellites, like those from SpaceX’s Starlink, continue to launch into Earth’s orbit. But what happens when they retire and burn up in the Earth’s atmosphere?
As Phys.org reports, a new peer-reviewed research paper estimates that the demise of so many satellites might threaten the Earth’s ozone layer. That’s because the satellites are bound to release harmful chemicals in the form of aluminum oxides when they descend through the atmosphere—a risk that has previously drawn concern from environmental groups.
The research, published in Geophysical Research Letters, comes from four scientists at the University of Southern California, who wanted to examine the effects of so-called “mega constellations” on potential ozone depletion.
SpaceX, Amazon, and other companies are working to build these mega constellations by launching thousands of low-Earth orbiting satellites in the coming years to power space-based internet services. These same constellations will also be refreshed over time as the older satellites deorbit, sending them on a path to completely burn up in the atmosphere.
(Credit: SpaceX)The problem is that these satellites are usually made of aluminum, which can generate harmful, ozone-depleting chemicals if released into the Earth’s atmosphere. The study found that the “demise of a typical 250-kg satellite can generate around 30 kg of aluminum oxide nanoparticles, which may endure for decades in the atmosphere.”
Correlating their findings to the amount of satellite-related space debris that has likely fallen through the Earth’s atmosphere in recent years, researchers estimate “an eight-fold increase in aluminum oxide compounds” within the atmosphere between 2016 to 2022.
The paper then estimates that the amount of aluminum oxide compounds could increase by over 20 times in the coming years, citing “increased reentry rates” from future satellite mega constellations. The result would create a 640% excess of aluminum oxide levels in the Earth’s mesosphere, which rests above the stratosphere, where the ozone layer mainly resides.
(Credit: European Environment Agency)“Due to their small size, the byproducts of spacecraft reentry can endure in the atmosphere and remain unnoticed until ozone concentration levels start decreasing,” the researchers added. “As reentry rates increase, it is crucial to further explore the concerns highlighted in this study.”
Although the research raises some alarm bells, it doesn’t offer an estimate on how much of the ozone layer could deplete, or if the effects would be minor. Current stats show the hole in the Earth's ozone layer has only slightly increased from 2022 to 2023.
SpaceX didn’t immediately respond to a request for comment. But the company has long defended Starlink against orbital hazard concerns. This has included working with scientists to prevent Starlink satellites from interfering with astronomical observations.