A SpaceX Falcon 9 rocket stage re-entered the atmosphere uncontrollably in February 2025, releasing vaporised metals that drifted over Europe. Researchers detected a significant spike in lithium from the debris, marking the first tracing of such pollution to a specific spacecraft. This incident highlights growing concerns over atmospheric impacts from increasing satellite launches.
In February 2025, the upper stage of a SpaceX Falcon 9 rocket, intended for reuse after splashing down in the Pacific Ocean, suffered an engine failure and lost control. It fell from orbit over the north Atlantic, burning up and producing a plume of vaporised metals, including lithium and aluminium, that spread across Europe.
Observers in Europe witnessed fiery debris streaking through the sky, with some pieces landing behind a warehouse in Poland. Prompted by news reports, Robin Wing and colleagues at the Leibniz Institute of Atmospheric Physics in Germany activated their lidar instrument. Twenty hours after re-entry, it recorded a 10-fold increase in lithium concentrations in the upper atmosphere as the plume, which had traveled 1,600 kilometers, passed overhead. This research, published in Communications Earth & Environment, represents the first instance of linking high-altitude pollution directly to a particular spacecraft re-entry.
The metal particles from such events may catalyse ozone destruction, form clouds in the stratosphere and mesosphere, and alter sunlight transmission through the atmosphere, according to Wing. "But all of this is understudied," he added.
With around 14,500 satellites currently in orbit, and SpaceX seeking approval for up to 1 million more to support orbital data centers for artificial intelligence, concerns are mounting. Satellites are deorbited to burn up at the end of their lives to prevent collisions, but this could multiply space debris particles by 50 times over the next decade, surpassing 40 percent of the mass from natural meteoroids.
The Falcon 9 incident released an estimated 30 kilograms of lithium, along with substantially more aluminium. Vaporised aluminium forms oxide particles that facilitate chlorine-induced ozone breakdown in the stratosphere. Annual emissions from spacecraft re-entries now total about 1,000 tonnes of aluminium oxide and are rising, potentially exacerbating the southern hemisphere's ozone hole despite progress from phasing out certain refrigerants.
Eloise Marais at University College London noted that anthropogenic sources are increasingly dominating upper atmospheric pollution, with space debris risking reversal of ozone recovery efforts. Additionally, these particles could nucleate cirrus clouds in the upper troposphere, which trap heat and contribute to warming, though the effect remains minor compared to carbon dioxide.
Daniel Cziczo at Purdue University emphasized debunking the idea that debris fully dissipates upon re-entry: "Let’s tap the brakes here, and let’s really do some thorough analysis of what effect this material could have." Potential mitigations include using alternative materials like wood for satellites—despite risks of black carbon release—or directing more to high-altitude graveyard orbits. Wing urged caution: "We need to take a little bit of time and think about what we’re doing before we do it."
