SpaceX Rocket Re-entry Linked to Lithium Pollution in Earth’s Atmosphere
Scientists have, for the first time, directly measured high-altitude atmospheric pollution resulting from the uncontrolled re-entry of a rocket stage – specifically, the upper stage of a SpaceX Falcon 9 rocket. The team detected a sudden tenfold increase in the concentration of lithium atoms in the atmosphere, a finding that raises concerns about the potential environmental impact of increasing space activity.
The research, conducted by the Leibniz Institute of Atmospheric Physics in Germany, focused on a plume of lithium observed in February 2025. Researchers were able to attribute the spike to the disintegration of the Falcon 9’s upper stage as it burned up in the Earth’s atmosphere.
Beyond this single event, the study suggests that “recurrent re-entries may maintain a higher level of anthropogenic metal and metallic oxide flux in the middle atmosphere, with relevant cumulative consequences for the climate,” according to the findings.
The Falcon 9’s upper stage is designed to burn up during re-entry, while the lower stage is reusable. However, the process of disintegration releases metals into the atmosphere. Lithium is widely used in spacecraft components, but is only found in trace amounts naturally at the altitudes where the pollution was detected – between approximately 50 and 85 kilometers above sea level (the mesosphere) and the lower thermosphere (85 to 120 kilometers).
The rocket stage re-entered the atmosphere off the west coast of Ireland, creating a spectacular fireball as it broke apart over Central Europe. The tenfold increase in lithium atoms was recorded in Germany approximately 20 hours after the uncontrolled re-entry. Analysis of reverse trajectories, including radar-measured wind variability, traced the air masses back to the Falcon 9’s re-entry path, 100 kilometers west of Ireland.
The lithium column extended from 97 kilometers above sea level and was observed by the researchers for 27 minutes before data recording ceased. These measurements demonstrate that ablation of spacecraft components, particularly those containing aluminum, begins at altitudes of up to 100 kilometers.
The research team emphasizes that this is the first instance of tracing high-altitude pollution directly to a specific spacecraft re-entry. The analysis of geomagnetic conditions, atmospheric dynamics, and ionospheric measurements “supports the claim that the increase [in lithium] was not of natural origin,” according to the study published in Communications Earth &. Environment.
The findings demonstrate, the team says, that it is possible to identify pollutants and trace them back to their sources, which “has important implications for the monitoring and mitigation of space emissions into the atmosphere.” The study also acknowledges that not all released material can be measured due to chemical changes occurring during descent.
Researchers utilized an atmospheric lidar radar, which accurately provides the distribution and properties of aerosols, facilitating a method for measuring this type of pollution.
The authors state that further observations and atmospheric chemistry modeling are needed to fully understand how these pollutants might affect the atmosphere in the long term. However, they warn that the amount of pollution in the upper atmosphere is likely to increase, given the substantial rise in orbital launches over the past decade. SpaceX, founded by Elon Musk, is planning to launch one million satellites in the coming years, potentially exacerbating the issue.
According to reports, around one to two Starlink satellites fall back to Earth each day by design. Each re-entry of a first-generation Starlink satellite produces approximately 30 kilograms of aluminum oxide vapor, a compound that can erode the ozone layer. Prior to 2019, only about 40 to 50 satellites re-entered the atmosphere annually, but SpaceX brought down ten years’ worth of satellites in just six months, adding an estimated 15,000 kilograms of aluminum oxide to the upper atmosphere.
The recent SpaceX Falcon 9 re-entry released approximately 30 kilograms of lithium, significantly more than the 50-80 grams of lithium deposited daily by small meteors.
