SpaceX’s Falcon 9 rocket has just had its invisible pollution studied for the first time

In February 2025, SpaceX’s Falcon 9 rocket caused a public sensation when its engine failed, causing an uncontrolled return to Earth. It was supposed to land in the Pacific Ocean, but rocket debris was bombed into parts of Europe. Large debris even landed within Polish city limits, putting populations in danger. Although SpaceX is quickly becoming the most valuable private company in the world, it has certainly caused controversy and allowed for a unique study on air pollution caused by the Falcon 9 rocket.

When the rocket broke up in the atmosphere, it released a plume of lithium vapor that drifted more than 1,000 miles across the European continent. Scientists used this event as a unique opportunity to study how spacecraft re-entry can introduce pollutants into the upper atmosphere and potentially change its chemical composition.

Researchers detected lithium levels about 10 times higher than normal in the upper atmosphere for about 20 hours after the Falcon 9 rocket returned over Europe. By modeling atmospheric winds, they were able to trace the lithium plume back to the rocket’s flight path, providing what they say is the first direct evidence of upper atmosphere pollution caused by reentry of space debris. The study was published in Nature in 2026.

The research team focused on lithium because it acts as a fingerprint of space debris. While many metals found in rockets can also come from natural sources such as meteors, lithium is extremely rare in Earth’s atmosphere and is usually only found in modern spacecraft.

To study the Falcon 9’s reentry, researchers combined data from different scientific instruments and computer models. Their most important observation comes from a lidar system in Germany, which uses lasers to detect tiny amounts of lithium in the atmosphere. During the night the rocket returned, the lidar recorded a massive spike in lithium levels. The research team then analyzed the data to ensure that any potential natural causes of lithium were excluded, so that only the amount caused by the Falcon 9 rocket was measured.

When it became clear that the rocket had increased atmospheric lithium levels 10 times higher than normal for nearly a full day, the science team sent its findings to SpaceX for comment or explanation. However, no response was received before the study was published. Elon Musk has big plans for SpaceX, including colonizing the Moon. For now, though, this study could raise some questions that SpaceX will need to consider.

One of the major points the study considered was the impact this could have on the environment, especially since this modern era of commercial space activity has seen SpaceX and other agencies launch rockets so frequently. So much so that SpaceX rocket explosions pose major safety concerns for airlines due to their debris trajectories.

Although this study focused on the reentry of a single Falcon 9 rocket, the researchers warn that the increasing number of spacecraft returning to Earth could lead to a steady buildup of metals and metal oxides – compounds formed when metals react with oxygen – in the atmosphere. Over time, these materials could potentially affect ozone chemistry and influence Earth’s climate by changing how the atmosphere absorbs and reflects energy.

However, since this study is the first of its kind, all of this information is new. The study highlights that much more research will need to be done to see if this magnitude of a lithium spike is consistent across all rocket reentries and to analyze how this lithium realistically moves through the atmosphere. Scientists are calling for rocket launches to be closely monitored in the future to better understand what short- and long-term impact they could have on the planet.