satellite soot – A new study by University College London researcher Eloise Marais says rocket launches and end-of-life satellite burn-ups release soot and other pollutants high in the atmosphere—effects that can cool the planet in a way that resembles geoengineering, even if
For millions of people using satellite internet and GPS every day, the benefits are invisible. But high above them, rocket launches are changing the air.
Professor Eloise Marais of University College London is studying pollution from satellite “mega constellations” and the climate implications of what happens both during launch and when satellites reach end of life. In her research. she points to two sources of air pollution linked to these growing networks: the rockets that put satellites into orbit release pollutants into the atmosphere as they climb through its layers. and. later. satellites must be discarded—often by burning them in the higher atmosphere until they disintegrate.
Marais describes soot as the key climate-relevant ingredient. The material from rocket launches includes black carbon. or soot particles—tiny suspended pieces that end up far above where most pollution originates. Once there, she says, they can block some of the sun’s incoming rays and cool the atmosphere. In that sense. she calls the effect “a little bit like a geo engineering experiment. ” echoing proposals that have been discussed for intentionally cooling the lower atmosphere.
Her caution is immediate: this cooling is not happening at large scale today.
The amount of black carbon produced by these rockets—mostly Falcon 9 rockets launched by SpaceX—is “very. very small” compared with pollution sources closer to Earth’s surface such as ships and cars. But Marais points out what makes the comparison complicated. Even if the initial effect is small. these particles linger: she says they stay in the atmosphere for about 2 1/2 to three years. “The longer a pollutant stays in the atmosphere, the bigger the effect they have,” she says. That means the footprint could grow quickly if the space industry expands—turning a small ongoing contribution into a larger climate factor over time.
The uncomfortable part is that the resemblance to geoengineering is happening without the careful planning that geoengineering debates have demanded. Marais acknowledges why people might see the cooling as attractive. Ideas for geoengineering are often framed around very quickly reducing warming caused by greenhouse gases. But she stresses that no one has done it at scale—because the risks are serious and wide-ranging. She points to possible unintended consequences including the depletion of ozone in the higher layers of the atmosphere and the disruption of atmospheric circulation patterns. processes that move air hundreds of kilometers in the higher layers.
In her framing, the space industry’s growing launches are creating an “accidental geo engineering experiment” without the ethical forethought that would normally come before deliberately changing the climate system.
That leads to a practical question: if the impact is real—even if unintended—what should governments do?
Marais says the problem is that there is no solid regulatory framework today to govern responsible. sustainable. and ethical use of space. She adds that the challenge is also structural: space is shared, meaning governments would have to work together. At the moment, she says, that coordination is a major hurdle.
satellites rocket emissions black carbon soot geoengineering climate impact atmospheric pollution ozone depletion satellite mega constellations Falcon 9 SpaceX