"This event has been described as the first direct observation of a pollutant plume from a specific piece of space debris reentry."

Lithium Plume Detected in Upper Atmosphere Tied to SpaceX Rocket Reentry

A study published in the journal Communications Earth & Environment has presented observational evidence linking the reentry of space debris to the presence of lithium in the upper atmosphere. Researchers utilized ground-based lidar technology to detect a lithium plume and traced its origin to the uncontrolled reentry of a SpaceX Falcon 9 rocket upper stage.

Key Findings

• On February 20, 2025, a lidar instrument in northern Germany detected a sudden tenfold increase in lithium atoms in the lower thermosphere. The plume extended from approximately 97 down to 94 kilometers above sea level and was observed for 27 minutes, beginning shortly after 00:20 UTC.
• Atmospheric wind models were used to calculate the plume's trajectory. The most probable source was identified as a Falcon 9 upper stage that reentered the atmosphere over the Atlantic Ocean, west of Ireland, approximately 20 hours prior to the observation.
• Researchers determined that natural atmospheric processes were an unlikely source of the detected lithium.
• This event has been described as the first direct observation of a pollutant plume from a specific piece of space debris reentry.
• The findings were published on May 1, 2026, in Advances in Space Research and simultaneously in Communications Earth & Environment.

Methodology

The research team, led by Robin Wing from the Leibniz Institute of Atmospheric Physics (IAP) in Germany, used a laser-based remote sensing instrument (lidar) to measure lithium atom concentrations in the lower thermosphere. Lithium is a component in some spacecraft materials, including lithium-ion batteries and lithium-aluminum alloys.

According to reports, a single Falcon 9 upper stage can contain approximately 30 kg of lithium within its tank walls. In comparison, an estimated 80 grams of lithium enter the atmosphere daily from cosmic dust particles.

The lidar instrument detected a lithium plume that was distinct from naturally occurring meteor material. The detection represents the first known demonstration of ground-based lidar detecting ablation from space debris.

Atmospheric Context

The study investigated an area of the upper atmosphere known as the Mesosphere and Lower Thermosphere (MLT), which lies approximately 50 to 120 kilometers above sea level. This region is critical for radio and GPS communications, atmospheric weather patterns, and the stratospheric ozone layer.

The research indicates that reentering satellites and rocket stages introduce materials that differ in composition from natural meteoroids, including aluminum alloys, composite structures, and rare earth elements.

Previous reports from the US National Oceanic and Atmospheric Administration (NOAA) have indicated that approximately 10 percent of sampled sulfuric acid particles in the stratosphere contain aluminum and other metals consistent with the burn-up of rockets and satellites. Some projections suggest this percentage could increase to as much as 50 percent in the coming years.

Ongoing Research and Recommendations

Michael Gerding of the IAP stated that lithium is a key species for investigating anthropogenic impacts on the middle atmosphere due to its use in the space industry. Leonard Schulz of the Technische Universität Braunschweig stated that there is a need for dedicated searches for space waste that survived reentry and impacted ground, along with detailed observations of space waste ablation.

The research team recommends coordinated, multi-site observations and whole-atmosphere chemistry-climate modeling to better understand how reentry emissions influence atmospheric chemistry and particle formation. The long-term effects of these pollutants on radiative transfer, ozone chemistry, and aerosol microphysics remain subjects of ongoing investigation.

The number of satellites in orbit has increased rapidly, currently at approximately 14,000. Projections indicate that several tonnes of spacecraft material could burn up in the upper atmosphere daily by 2030. Currently, there is no specific regulatory framework for these emissions, and monitoring options remain limited.