Look up on a clear night and you’ll see the streaks of our new space age. What you don’t see is the growing fallout for the atmosphere that keeps us alive.

A wave of satellite launches and reentries is changing the chemistry and physics of the middle and upper atmosphere.

Studies warn of ozone depletion, stratospheric heating and new metal aerosols from burning spacecraft. The pace is accelerating fast and unless we redesign how we use and retire satellites, we risk swapping one environmental problem (congestion in Earth orbit from too many spacecraft) for another (an atmosphere seeded with rocket soot and satellite ash).

The problem is that most satellites are de-orbited when they reach the end of their lives. Essentially, they self-destruct in the Earth’s atmosphere, disintegrating as they are heated to thousands of degrees Celsius. But there is an increasing move to extend the lives of satellites in orbit by, for example, refuelling them. They could also be de-orbited in a gentler manner, so that parts can be reused.

Orbital launches hit fresh records in 2024 and 2025 as companies raced to establish and refresh mega-constellations, which are large networks of many satellites launched to provide a particular service, such as internet access.

SpaceX’s Starlink is one example. Independent estimates report between 259 and 271 launches in 2024 and more than 315 in 2025, driven largely by commercial broadband fleets. That launch pace means unprecedented reentry traffic: thousands of satellites self destructing in the atmosphere.

Researchers estimate that by the 2030s, re-entering satellites could inject thousands to........

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