The news
SpaceX launched 27 more Starlink satellites on 27 October on a Falcon 9 rocket from Vandenberg in California. According to the website Orbital Radar, 10,077 Starlink satellites were working on 17 October. From the start of 2026 to 17 October, another 439 Starlink satellites fell back into the atmosphere and burned up, which is about 1.5 satellites a day. A satellite’s body contains aluminum, and when it burns it turns into very fine particles of aluminum oxide. Researchers worry that these particles could damage the ozone layer. The ozone layer is a layer of gas high in the atmosphere that protects us from the Sun’s harmful rays.
How Starlink satellites could hurt the ozone layer
- Probable: In 2024, researchers at the University of Southern California used a computer model to calculate that the satellites that burned up in 2022 left about 17 tonnes of aluminum oxide at a height of 50 to 85 kilometers above the Earth. By their calculation, a 250 kg satellite makes about 30 kg of these particles as it burns.
- Probable: The same study says the particles help the chlorine in the air break down ozone. The particles are not used up in this process, so they can keep breaking down ozone for years. It can take up to 30 years for them to sink from that height to the ozone layer.
- Certain: In 2023, researchers from the US National Oceanic and Atmospheric Administration and Purdue University took air samples from an aircraft. In the part of the atmosphere that holds the ozone layer, about 10% of the sulfuric acid particles wider than 120 nanometers contained aluminum and other metals from burned-up spacecraft.
- Probable: Satellite companies plan to launch many more satellites. The University of Southern California researchers calculated that if all of them are in orbit and burn up when their work ends, more than 360 tonnes of aluminum oxide will reach the atmosphere every year. That is more than seven times the amount of aluminum oxide that nature puts at the same height.
How Starlink satellites could help the Earth
- Certain: A satellite that has finished its work burns up in the atmosphere and does not stay in orbit as space junk. From the start of 2026 to 17 October, 439 satellites left orbit this way. This figure comes from Orbital Radar.
- Our estimate: Today’s amount is still below the forecast. If each of those satellites weighs 250 kg and makes 30 kg of aluminum oxide, the total for all 439 is about 13 tonnes. That is less than 4% of 360 tonnes. If the satellites are heavier, the total is higher.
Our conclusion
For the Earth, burning satellites up in the atmosphere solves the problem of space junk, but it sends metal into the upper atmosphere in return. Today’s amount is small, but it grows as the number of satellites grows. In our view, until the effect of these particles on ozone has been measured, the amount of aluminum that burns up in the atmosphere should not rise.
We suggest that SpaceX publish every year the weight of every satellite that burns up and the materials it is made of, and that atmospheric agencies measure the amount of aluminum oxide in the upper atmosphere.
Tell us what you think
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Sources
- Spaceflight Now, West Coast Falcon 9 rocket launches 27 Starlink satellites, 27 October 2026.
- Orbital Radar, Starlink reentries per day (data to 17 October 2026).
- Ferreira et al., Potential Ozone Depletion From Satellite Demise During Atmospheric Reentry in the Era of Mega-Constellations, Geophysical Research Letters, 2024.
- Phys.org, Satellite megaconstellations may jeopardize recovery of ozone hole, June 2024.
- Murphy et al., Metals from spacecraft reentry in stratospheric aerosol particles, PNAS, 16 October 2023.
