Lasers shine a new light on the space junk air pollution problem

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Scientists are using a new technique to study incoming space debris and its effects on Earth's atmosphere.

Observational evidence is being gathered that the ablation of space debris can be detected by ground-based light detection and ranging (LiDAR), a remote-sensing technology that uses laser beams to measure precise distances and movement in an environment, in real time.

Last year, for the first time, a lithium cloud in the upper atmosphere was linked to the reentry of a rocket stage. This event took place on Feb. 19-20, 2025 with the detection of a lithium cloud 10 times higher than is typical. Back-trajectory analysis indicated the lidar-probed air mass originated from a location west of Ireland that coincided with the atmospheric reentry of a SpaceX Falcon 9 upper stage.

Anthropogenic impacts

"Lithium is a crucial species for investigating anthropogenic impacts on the middle atmosphere because of its extensive use in the space industry," reported Michael Gerding, a scientist in the optical and rocket soundings department of the Leibniz Institute of Atmospheric Physics (IAP) at the University of Rostock in Kühlungsborn, Germany.

"Ablation of reentering satellites and rocket stages is expected to become a significant source of metals in the mesosphere, yet systematic observations remain limited so far," Gerding reported at the 2026 European Geosciences Union, which was held May 3-8 in Vienna.

Gerding also showed the first results of IAP's new three-channel multi-species lidar that's set up to search for different materials expected to be ablated by reentering space debris. These materials include copper, aluminum oxide, and hydrogen fluoride, which is used as a propellant in some rocket engines.

"These materials, which naturally occur only in trace amounts at such altitudes, are influencing the mesosphere and upper stratosphere to an extent not previously documented. This influence is expected to intensify further in the coming years," explains the IAP website.

Test measurements

According to the IAP, with the rising number of satellite launches and space activities — particularly the surge in placing satellite megaconstellations into Earth orbit — the composition of the upper atmosphere is changing.

Robin Wing, also an IAP scientist, told Space.com that the new multi-species lidar system is coming along. "We have done test measurements," Wing said, "and are currently improving some subsystems."

Wing said the upgraded lidar gear includes a survey channel that systematically looks for each spacecraft element, with copper being the first target.

Space waste

Leonard Schulz is a researcher at the Technische Universität Braunschweig's Institute of Geophysics and Extraterrestrial Physics in Germany.

In a study published in the May 1 issue of the journal Advances in Space Research, Schulz and colleagues pointed out that incoming "space waste" is injecting a significant amount of its matter into the mesosphere and lower thermosphere — enough to cause concern for Earth's ozone layer.

"There is a need for dedicated searches for space waste that survived reentry and impacted ground, detailed observations of space waste ablation, and further ground experiments representative of the conditions of atmosphere reentry," Schulz and team members wrote in the study.

"Today's large satellite constellations amplify the problem of on-orbit space debris as well as the ground risk from impacts," the researchers added.

"Beside these well-discussed problems," they concluded, the new findings "indicate a substantial risk associated with space waste reentry and possible effects on Earth's atmosphere and thus the human habitat."

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Leonard David is an award-winning space journalist who has been reporting on space activities for more than 50 years. Currently writing as Space.com's Space Insider Columnist among his other projects, Leonard has authored numerous books on space exploration, Mars missions and more, with his latest being "Moon Rush: The New Space Race" published in 2019 by National Geographic. He also wrote "Mars: Our Future on the Red Planet" released in 2016 by National Geographic. Leonard  has served as a correspondent for SpaceNews, Scientific American and Aerospace America for the AIAA. He has received many awards, including the first Ordway Award for Sustained Excellence in Spaceflight History in 2015 at the AAS Wernher von Braun Memorial Symposium. You can find out Leonard's latest project at his website and on Twitter.