Falcon 9 reentry pollutes upper atmosphere, Pg2

Key Highlights:

• Researchers tracked a plume of metal vapor from a Falcon 9 rocket reentry on February 19, 2025, confirming space traffic alters the upper atmosphere's chemistry.
• The study, published in Communications Earth & Environment, used a resonance lidar in Germany to detect a surge in lithium atoms 96 km above the surface.
• The lithium concentration was 10 times higher than natural levels, linked to the rocket's disintegration over the west coast of Ireland.
• Falcon 9 rockets contain roughly 30 kg of lithium, used in lithium-aluminum alloys and lithium-ion batteries.

Detailed Insights:

• The rise of mega-constellations like Starlink, with thousands of satellites designed to de-orbit and burn up, is increasing atmospheric pollution.
• The reentry of these satellites injects metals like aluminum and lithium into the mesosphere and lower thermosphere (MLT).
• Scientists are concerned this pollution could harm the ozone layer and change how the atmosphere traps heat, impacting climate.
• Natural space dust contributes only about 80 g of natural lithium to Earth per day, highlighting the significant impact of rocket reentries.
• Tracking pollutants from space is crucial as human-made objects re-entering the atmosphere rival the mass of natural meteors.
• The upper atmosphere offers a valuable opportunity to observe ablated materials before they undergo chemical transformation and dispersion.

Scientific/Technical Concepts Involved:

• Resonance Lidar: A remote sensing technology that uses lasers to measure the concentration and distribution of specific atoms or molecules in the atmosphere.
• Mesosphere and Lower Thermosphere (MLT): The region of the atmosphere between approximately 50 km and 150 km above the Earth's surface.
• Ablated Materials: Materials vaporized or removed from a spacecraft or meteoroid due to intense heat during atmospheric entry.