By BlueShift | 2026-03-03

When part of a rocket re-entered Earth's atmosphere a year ago, it created a fireball that streaked across Europe's skies and sent a team of scientists rushing for their instruments.

The team managed to measure the contamination the rocket's upper stage emitted in the difficult-to-study upper atmosphere, publishing its findings February 19 in the Communications Earth & Environment journal.

The study presents the first measurement of upper-atmospheric contamination resulting from space debris re-entry and the first observational evidence that the ablation of space debris can be detected by ground-based LiDAR.

Light Detection and Ranging (LiDAR) technology measures contamination in the atmosphere by shooting out laser pulses and seeing which bounce back.

It is the first time scientists have linked atmospheric contamination back to a specific piece of space debris, according to Sky & Telescope.

No previous direct attempt to investigate the aftermath of a large reentry using LiDAR had been successful, largely because most spacecraft are deliberately steered to de-orbit over unpopulated areas, it said.

"The unplanned crash over Europe thus presented a unique opportunity."

The SpaceX Falcon 9 upper stage failed to de-orbit over the Pacific Ocean as intended, per Sky & Telescope, and in the early hours of February 19, 2025, it was tumbling back to Earth when it exploded into a fireball.

Tracing pollution to source

"We were excited to try and test our equipment and hopefully measure the debris trail," the team led by Robin Wing and Gerd Baumgarten of the Leibniz Institute of Atmospheric Physics in Germany told AFP via email.

In particular, the scientists wanted to measure the impact on the "ignorosphere," which is so difficult to study. This region between 50 to 100 km above Earth includes the mesosphere and part of the lower thermosphere.

Using LiDAR, the team detected a sudden spike in the metal lithium in an area nearly 100km above Earth. This plume had 10 times more lithium than is normal in this part of the atmosphere.

They then traced the plume back to where the rocket re-entered the atmosphere, west of Ireland.

For the first time, this proves it is possible to study contamination from re-entering rockets at such heights before it disperses, the scientists said.

"Our findings demonstrate that identifying pollutants and tracing them to their sources is achievable, with significant implications for monitoring and mitigating space emissions in the atmosphere," the study's abstract said.

It is vital to learn more about little-understood upper-atmospheric contamination because of the huge number of satellites that are planned to be launched in the coming years, the authors stressed.

A harbinger of things to come

The study warned the case was a "harbinger" of future contamination, given how many rockets will be needed to launch all the satellites that Earth is planning to blast into space.

"The increasing frequency of satellite and rocket re-entries is an emerging societal and scientific concern," it said.

"While the risks to people and infrastructure from falling debris are widely discussed, less attention has been paid to the environmental consequences for Earth’s atmosphere," the study said.

"The so-called 'New Space Age' is characterized by the rapid deployment of commercial mega-constellations in low Earth orbit (LEO) consisting of tens of thousands of satellites," it said.

"This development represents not only a dramatic increase in satellite numbers but also a significant rise in total orbital mass."

Currently, there are around 14,000 active satellites orbiting our planet.

In January, China applied for permission to launch around 200,000 satellites into orbit, and SpaceX applied for permission to launch one million more.

China has faced criticism on several occasions for its failure to share critical information about the uncontrolled reentry of space debris, including a potentially hazardous booster rocket in 2022 and a recent incident in Australia.

Eloise Marais, a professor of atmospheric chemistry at University College London not involved in the new study, told AFP the research was "really important."

"There is currently no suitable regulation targeting pollution input into the upper layers of the atmosphere," she said, noting the "potentially consequential impacts to life on Earth."