Time-exposed image of the Hale Bopp comet at sunset, as seen over the earth's atmosphere during Space Shuttle Columbia mission STS-83, 4th to 8th April 1997. STS-83 is a science research mission that was cut short after four days, instead of a planned 15-day duration (Image via Getty)
A Falcon 9 rocket which carried 22 Starlink satellites experienced a malfunction in February 2025 when it failed to execute its scheduled deorbit burn.
The rocket drifted for 18 days before beginning an uncontrolled descent approximately 100 kilometers off the west coast of Ireland.
An accident in Poland resulted in debris falling there which caused no injuries but resulted in the termination of Poland's space agency director.
Researchers at the Leibniz Institute for Atmospheric Physics led by Robin Wing discovered a lithium plume which they traced back to the upper atmosphere after the reentry event.
Their findings which they published in Communications Earth & Environment present the first direct proof of upper-atmospheric pollution which results from rocket reentry.
Upper-Atmosphere Pollution Linked to Rocket Reentries
Detection of the Lithium Plume
Wing and colleagues used a resonance fluorescence lidar system in Kühlungsborn, Germany, to monitor the upper atmosphere.
On February 20, 2025, around midnight, the instrument detected a sudden increase in lithium vapor levels.
Background lithium concentrations in the upper atmosphere are normally around three atoms per cubic centimeter.
Measurements showed a spike to 31 atoms per cubic centimeter between 94.5 and 96.8 kilometers above sea level, approximately 20 hours after the Falcon 9 descent.
The lidar system recorded the plume for 27 minutes until data collection ceased.
The spike in lithium coincided precisely with the descent of the Falcon 9 upper stage, indicating a direct connection between the reentry and the observed plume.
Linking the Plume to a Specific Rocket
To determine the source, the team used atmospheric wind models to trace the path of the lithium back to the reentry point over the Atlantic Ocean west of Ireland.
They ran 8,000 backward wind simulations from their lidar station to the Falcon 9 trajectory. Other potential sources of lithium were investigated and ruled out.
Falcon 9 upper stages contain roughly 30 kilograms of lithium, including lithium-ion batteries and aluminum-lithium alloy hull plating.
Implications for Atmospheric Studies
Previous research on space debris reentry has focused on the risk of debris reaching the ground. Wing et al. noted that the effects on the mesosphere (50–85 kilometers) and lower thermosphere (85–120 kilometers) are less understood.
Their study represents a first case of measuring upper-atmosphere pollution from a single rocket stage.
The authors emphasize that not all materials released during reentry can be measured due to chemical transformations during descent.
They also highlight that further lidar observations and atmospheric chemistry modeling will be necessary to understand potential long-term effects.
Increasing Relevance with Satellite Launches
The increase in orbital launches creates a need to monitor chemical emissions from space debris.
The research conducted by Wing and her team developed a technique to identify and study pollutants present in the upper atmosphere.
The research establishes a system to track future Falcon 9 reentry events and their effects on atmospheric makeup.
The research demonstrates that rocket reentries release detectable amounts of lithium into the upper atmosphere which scientists need to consider for environmental assessment and satellite deorbiting methods.
The study shows that the expansion of megaconstellations in low Earth orbit creates an urgent requirement for ongoing surveillance.
