Scientists are calling for a new global regime to address air pollution caused by the space industry.
Prof Eloise Marais’s team at University College London (UCL) began tracking space activities in 2020. Their latest figures reveal 259 rocket launches in 2024, and 223 launches in 2023. These burned more than 153,000 tonnes of fuel.
Marais said: “More pollutants are being released into the atmosphere from rockets and satellites than ever before. We’re in uncharted territory, as humans have never added this much pollution to the upper layers of the atmosphere. If left unregulated, it may have serious impacts on Earth’s atmosphere.”
The team found that launches of mega-constellation communication satellites, including Starlink, OneWeb and Thousand Sails, have led to a threefold increase in emissions of climate-altering soot and carbon dioxide.
Although the amount of CO2 and soot from spacecraft is far less than other industries, researchers have warned that particles stay in the upper atmosphere much longer than Earth-bound sources. This results in up to 500 times greater climate warming impact than the same amount of soot from aviation or ground-level sources.
Marais said: “The amount of propellant used to launch mega-constellations has surpassed the amount of propellant used to launch all other missions combined. The mix of pollutants produced is likely going to change in the future with the advent of Amazon Kuiper mega-constellations. These plan to use the European Space Agency’s rocket that is propelled by solid rocket fuel and produces ozone-damaging chlorine compounds.”
Dr Connor Barker from UCL said: “Many more mega-constellations are planned for launch in the next few decades, which will have significant impacts for our climate, and undo progress made by the Montreal protocol to repair the ozone layer.”
The biggest change has been in the sheer number of objects launched and in orbit. In the late 1960s and 2016, 100 to 200 objects a year were launched into space, but now it is thousands each year and they have limited lifetimes.
Many of us will have been looking up at the night sky as the Perseids meteors reached their peak this month. Also obvious is the sheer number of satellites in orbit clearly visible to the naked eye as small bright dots slowly making their way from horizon to horizon.
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Prof Stuart Martin, the chair of trustees at the UK National Space Centre, said: “Current international law very much related to the principles of the high seas. The country that launched an object, owns it, and only the laws of that country apply to the object in space. This is one of the reasons why things like cleaning up is so difficult.”
Already many of these mega-constellation satellites are re-entering the atmosphere, vaporising into tiny and sometimes chemically reactive metal particles. The UCL team tracked 2,539 objects burning up on re-entry in 2024 and 2,016 objects in 2023, amounting to 13,500 tonnes of material from satellites, as well as discarded rocket parts.
