As the number of satellites in orbit increases, so does the number of decommissioned ones which fall toward Earth, threatening the atmosphere and releasing pollutants from above. There are currently more than 10,000 active satellites, of which about 6,591 belong to SpaceX’s Starlink constellation. Others are operated by companies such as Amazon, OneWeb (based in the UK) and new Chinese ventures, which plan to put more than 15,000 satellites into orbit in the next few years.
According to experts, the average operational life of a satellite is about five years. After this period is over, many are disposed of by returning them to the atmosphere, where they disintegrate by burning. This process, however, releases aluminum oxide particles and other heavy metals into the upper atmosphere, which can impair the climate and hinder the recovery of the already compromised ozone layer.
During re-entry, satellites can appear like comets to those watching from Earth. But the environmental risks are real. The increasing crowding of low Earth orbit (LEO) raises concerns not only about pollution, but also about the risk of collisions. In 2024 alone, more than 2,500 man-made objects were launched, and it is estimated that nearly 50,000 fragments larger than 10 cm could orbit by 2050.
Like greenhouse gas emissions, space debris can have cumulative harmful effects, exacerbating global environmental impacts. And all this occurs in a geopolitical context where environmental policies struggle to keep pace with technological development.
According to a study published in the Journal of Geophysical Research: Atmospheres, substances released during the re-entry of satellites are concentrated at high latitudes, causing temperature anomalies of up to 1.5°C in the mid to upper atmosphere, reduced wind speeds and possible ozone depletion, which could become irreversible. In addition to aluminum oxide, metals such as titanium, lithium, iron and copper are also being released into the stratosphere, but their impact is still poorly understood.
Further complicating the situation is the lack of an effective regulatory framework: current environmental laws do not consider pollution from space, leaving this new form of contamination virtually unregulated.
As Josef Aschbacher, director general of the European Space Agency (ESA), said, “The message is crystal clear: space debris is a problem and we need to do something about it.”
