Metal pollution from a rocket reentry detected for the first time

For the first time, scientists have directly observed metal pollutants leaching from a piece of orbital junk: a SpaceX rocket as it burned in the atmosphere. Such pollutants can damage the ozone layer, meaning the findings will help monitor potential harms from space debris, researchers report February 19 in Communications Earth and Environment.

While humans have been launching metal things to orbit for nearly 70 years, the pace has skyrocketed in the past decade. Private companies plan to escalate this in the near future — for instance, SpaceX’s Starlink system, which provides internet to far-flung places, will eventually consist of more than 40,000 satellites in low-Earth orbit. Nearly 10,000 are currently orbiting Earth.

Each piece of equipment has a planned lifetime of about five years, after which it burns up in the upper atmosphere, releasing metals such as lithium, aluminum and copper, all of which may catalyze chemical reactions that destroy ozone and have other adverse effects. A 2023 study found that about 10 percent of stratospheric particles contain pollutants from burnt-up satellites and rocket stages.

That motivated a research team to see if they could directly trace such particles to a piece of reentering space debris. On February 19, 2025, the researchers observed a cloud of lithium about 100 kilometers above Germany blowing out of a Falcon 9 rocket’s upper stage disintegrating over Ireland and the United Kingdom.

“A few hours after the reentry of this rocket, we could see 10 times more lithium than we would have observed otherwise,” says Claudia Stolle, a meteorologist at the Leibniz Institute of Atmospheric Physics in Germany.

The measurements relied on lidar, which shoots laser pulses tuned to specific wavelengths that bounce off particular materials, such as lithium. The team also ran sophisticated atmospheric simulations to show that the prevailing winds had carried the lithium plume from the spot where the rocket came down in over the North Atlantic to the area over Kühlungsborn, Germany, where the lidar was located.

Though there is a natural influx of metals into the atmosphere from meteorites, the combined load of all reentering space debris may one day boost metal pollution by around 40 percent, Stolle and her colleagues conclude. Tracking such contaminants and their effects will become increasingly important as more companies and countries get interested in launching satellites to orbit.

“All of them will burn up sooner or later,” Stolle says.