For the first time in history, scientists have observed in near real time clouds of air pollution formed as space debris burns up in Earth’s atmosphere. This groundbreaking measurement will help atmospheric chemistry researchers unravel the complex chemical reactions caused by toxic air pollution that occur during atmospheric reentry, which can have devastating effects on Earth’s atmosphere and climate.
A cloud of lithium was detected on the upper stage of SpaceX’s Falcon 9 rocket on February 20, 2025. crashed over europedebris is scattered throughout Poland. A team of researchers from the Leibniz Institute for Atmospheric Physics in Germany made the detection using LIDAR, a pulsed laser instrument that excites specific chemical elements based on the frequency of light.
“We thought it was a good opportunity, so we checked the wind and it looked good, so we fired up the LIDAR and took measurements the next night,” Wing said. “When we processed the data, we observed a very strong signal with a 10-fold increase in lithium density at almost the exact time and at almost the exact altitude.”
Wing said most of the rocket evaporated at an altitude of about 60 miles (96 kilometers) above the Irish coast. It then took about 20 hours for the resulting plume of air pollution to be carried by winds across Western Europe and into Germany. Meanwhile, pieces of debris traveled 930 miles (1,500 kilometers) from Ireland to western Poland in about two and a half minutes.
To confirm whether the plume was indeed the result of Falcon 9’s re-entry, the researchers performed back calculations using a global atmospheric circulation model from the European Center for Medium-Range Weather Forecasts. The model placed the plume at a location that would intersect the trajectory of the Falcon 9 debris as it reentered at the correct time.
The researchers focused on lithium, which naturally exists in trace amounts in the atmosphere.
“We believe that lithium is an excellent tracer for: [human-made] “Natural meteorites contain very little lithium, estimated around 80 grams per day worldwide. But a single Falcon 9 rocket, with its aluminum and lithium hull and lithium battery, has about 30 kilograms.”
Space debris reentry has become a growing concern in recent years. As the number of satellites in orbit has skyrocketed over the past decade, the amount of space junk disappearing into Earth’s atmosphere has increased accordingly. The European Space Agency estimates that: 3 or more space debris — Old satellites, spent rocket stages, and all kinds of debris spiral back to Earth every day.
Hundreds of tons of space junk burns up in the atmosphere every year, releasing chemicals that don’t occur naturally. The total amount of re-entering junk is only a fraction of the amount of natural meteorites that Earth encounters. But scientists believe that unlike natural space rocks, air pollution from space junk can damage the protective ozone layer and alter the thermal balance.
Wing said most of the scientific discussion so far has focused on aluminum, the most abundant metal in spacecraft fuselages, and little is known about lithium’s effects on atmospheric processes. Aluminum is known to react with oxygen during atmospheric combustion to form aluminum oxide, or alumina. Alumina is a powdered substance known to accelerate ozone layer depletion, change atmospheric reflectance, and potentially cause temperature changes on Earth.
“Measuring aluminum is actually very difficult,” Wing says. “Aluminum reacts with oxygen very quickly, within microseconds. So the moment the aluminum evaporates from the rocket hull, it combines with the first oxygen atom it finds.”
In the future, researchers hope to use LIDAR instruments to measure aluminum oxide concentrations after reentry.
Eloisa Marais, Professor of Atmospheric Chemistry and Air Quality at University College London and a leading expert on the effects of air pollution from space debris, said: “This study marks an important milestone in observing the effects of space sector activities on the atmosphere, especially now that ablation reentry is “Given that it is the only viable and scalable way to clean up an increasingly messy orbit,” Eloisa Marais, professor of atmospheric chemistry and air quality at University College London and a leading expert on the effects of air pollution from space debris, commented on the study.
“Insights from this study, and hopefully similar follow-on and related studies, will be critical to improving our models, as we rely on these insights to assess the effects of spacecraft reentry on the Earth’s environment.”
Scientists have speculated for years about the effects that increasing amounts of re-entering space debris will have on the atmosphere. A 2023 study based on measurements from high-altitude aircraft confirmed that about 10 percent of aerosol particles are in the stratosphere (Earth’s second layer). earth’s atmosphere At altitudes between 16 and 50 miles, Contains metal particles From an incinerated satellite. A new paper links specific re-entries to visible air pollution plumes for the first time.
“For the first time, we can directly demonstrate that we have the ability to track and observe contamination plumes from space debris to a single reentry event,” Wing said. “This is a bit of a breakthrough, both observationally and computationally. It’s just never been done before.”
Leibniz’s team will continue to make observations. Since the successful detection in February 2025 falcon 9 After atmospheric reentry, they built a new LIDAR instrument that could measure traces of multiple metal compounds simultaneously.
“We’ll measure lithium, a tracer in space debris, sodium, a tracer in natural meteorites, and we’ll scan all the different elements present in the spacecraft, including copper, titanium, silicon, gold, silver, and lead,” Wing said. “So we’ll be able to actually try to estimate what’s coming into the atmosphere and how much of it is anthropogenic. This could give our colleagues who do atmospheric and chemical modeling a hint at how space debris re-entry might affect the stratosphere.”
of study was published in the Nature Family Journal Communications Earth & Environmental on Thursday, February 19, 2026.