In February 2025, a SpaceX Falcon 9 rocket carrying 22 Starlink satellites suffered a malfunction and failed to execute the planned deorbit burn. It remained adrift in orbit for 18 days before descending uncontrollably near the west coast of Ireland. Some parts fell in Poland, causing no injuries, but the episode generated political and scientific concern.
A study led by Robin Wing and colleagues from the Leibniz Institute of Atmospheric Physics revealed that the reentry of the Falcon 9 caused a lithium cloud in the upper atmosphere. Using a resonance fluorescence lidar system in Kühlungsborn, Germany, the researchers detected a spike in lithium vapor levels just after the rocket’s descent.
Normally, the atmosphere contains only 3 lithium atoms per cm³, but 20 hours after the event, the density skyrocketed to 31 atoms per cm³ between 94.5 and 96.8 km altitude.
Lithium as a Pollutant
Lithium is a key component of the Falcon 9’s upper stage, present in the lithium-ion batteries and in the aluminum-lithium alloy coating of the hull. It is estimated that the stage contained about 30 kg of lithium, compared to the mere 80 grams daily contributed by meteorites to the global atmosphere.
Atmospheric models confirmed that the detected cloud coincided with the rocket’s reentry, ruling out other possible sources.
Environmental Implications
This is the first documented case where a space incident is directly linked to an atmospheric pollution cloud. The finding raises crucial questions:
- What impact will lithium have on atmospheric chemistry?
- How can the risk of contamination be limited in the intentional deorbiting of satellites and rockets?
- What consequences might the increase in launches have on communication megaconstellations?
Technology and Modeling
Scientists conducted more than 8,000 wind trajectory simulations to trace the cloud back to the point of reentry. Additionally, they identified that the Falcon 9’s coating begins to melt at 98.2 km altitude, coinciding with observations.
This approach combines direct observations with atmospheric modeling, offering a method to track pollutants derived from space activity.
A Growing Challenge
As satellite and rocket launches increase, space and atmospheric pollution becomes a topic of growing relevance. Scientists warn that understanding and mitigating these impacts will be essential to ensure the sustainability of space operations.
The case of the Falcon 9 and the lithium cloud sets a precedent in space-related environmental research. Beyond the anecdote, it opens a debate on the need to regulate and monitor the effects of the space industry on Earth’s atmosphere. This study is just the first step towards a deeper understanding of how our activities beyond the planet can alter Earth’s chemical balance.
