“Chlorine is one of the key actors in the ozone hole,” said John Dykema, an applied physicist at Harvard School of Engineering and Applied Sciences. He was talking about what happens when satellites burn up, and SpaceX has just reported a lot of them doing exactly that.
In its semi-annual report to the Federal Communications Commission, SpaceX said it deorbited 260 Starlink satellites between December 2025 and May 2026. The count was 176 first-generation satellites and 84 of the bigger second-generation ones. Engadget’s take was blunt: the number sounds large, but it is not unusual.
Bigger years on record
In 2024, SpaceX found a common issue in a small group of version-one satellites that could raise the chance of failure. It brought down 406 satellites in response, then followed with nearly 500 from December 2024 to May 2025.
There is no fixed schedule. Orbital Radar, a satellite tracking platform, counts more than 9,500 active Starlink satellites, so retirements are common. SpaceX has also applied to the FCC to launch a million satellites for an orbital data center for SpaceXAI.
Where and how they come down
SpaceX prefers not to wait for satellites to fail. “Controlled, propulsive deorbit is much shorter and safer than a comparable uncontrolled, ballistic deorbit from an equivalent altitude,” the company said, adding that it lets satellites keep their maneuverability and collision avoidance during the descent.
The company usually aims for open ocean, away from populated islands and busy air or sea lanes. To pick the spot, it holds attitude control down to around 125 km. One collision could do heavy damage to the satellite broadband industry.
Not everything vanishes. SpaceX has acknowledged that some parts have high melting temperatures. For the V2 mini, it believes silicon from the solar cells could make it through. It predicts about 5 percent of a satellite’s mass could survive, in tiny fragments with negligible impact energy. Engadget summed that up as a small splash in the ocean.
Satellites fly below 600 kilometers, where atmospheric drag would bring one down naturally within five years, the company says in its sustainability document. An FCC rule adopted in 2022 requires low Earth orbit operators to deorbit within five years of mission completion.
This year, Michael Nicolls, VP for Starlink Engineering at SpaceX, announced that satellites flying near 550 kilometers will be lowered to 480 kilometers through 2026. He said the number of debris objects and planned constellations is “significantly lower below 500 kilometers,” “reducing the aggregate likelihood of collision.” Deorbiting from there is also quicker. Elon Musk said the lower shell will let Starlink serve a higher density of customers.
The ozone question
Scientists are still working out whether any of this affects the atmosphere. Harvard Climate Brief notes that burning organic materials such as carbon-fiber composites releases black carbon, or soot. Its effect, if any, is unclear.
Aluminum is the bigger worry. When it burns, it can form aluminum oxide particles, and those particles could convert ambient chlorine into a highly reactive form. “And so if you add a new surface that converts existing chlorine into reactive and free radical forms, that will also promote ozone loss,” Dykema said.
He does not see cause for alarm yet. But if aluminum oxide keeps accumulating as deorbits become more frequent, it could slow the recovery of the ozone layer, which began when chlorofluorocarbons were phased out in 1987. American and Chinese companies are both launching big batches for their own megaconstellations, and Amazon is building one for its Leo broadband service.
