Black carbon particles released by rocket launches remain in the upper atmosphere for much longer than sooty particles produced by sources on the ground. This finding, which comes from a study led by researchers at University College London (UCL), UK, suggests that the soot created in deploying “megaconstellations” containing hundreds or thousands of satellites could have poorly understood and potentially serious consequences for the Earth’s climate.

“Rocket launches are a unique source of pollution, injecting harmful chemicals directly into the upper layers of the atmosphere and contaminating Earth’s last remaining relatively pristine environment,” says the study’s lead author, UCL atmospheric chemist Connor Barker.

The number of rockets being launched into space has increased dramatically since 2019, and the trend shows few signs of stopping. This year has already seen more launches than the whole of 2020, and space industry experts believe the eventual total could surpass 2025’s figure of 329. The increase has primarily been driven by the Falcon 9 rockets launched by the US firm SpaceX, though China also logged a record 92 launch attempts in 2025.

“An unregulated geoengineering experiment”

In the new work, Barker and colleagues analysed data from rocket launches and satellite re-entries from 2020 to 2022. Their results, which they detail in Earth’s Future, show that the soot particles lingering in the upper atmosphere are 540 times more effective at altering climate than ground-based soot emissions from sources such as cars and power plants.

“Space industry pollution is like an unregulated geoengineering experiment,” says Barker. Soot particles from burning kerosene in rocket fuel absorb sunlight, he explains, which prevents it from reaching the Earth’s surface. The result is a small cooling effect, which might sound like a good thing in the context of rising global temperatures. However, Barker stresses that this cooling is minimal compared to the global warming caused by other human-generated emissions, while the particles themselves could have “many other serious unintended consequences”.

Predictions likely to underestimate future impact

As well as quantifying recent space industry emissions, the researchers make predictions about future ones. According to their calculations, by 2029 the space industry will be releasing about 870 tonnes of soot into the atmosphere each year. By way of comparison, Baker notes that according to the latest UK government figures, the annual emissions of the country’s entire passenger car fleet amounted to just 728 tonnes.

The team based its predictions on projections of data from 2020-2022, which is considered the beginning of the megaconstellation satellite era. Because of this, Barker cautions that they are likely to be underestimates, making the problem even more urgent. “It is critical that we understand the environmental impacts of satellite megaconstellations now while their impact is small, before any unforeseen consequences are difficult to reverse or repair,” he tells Physics World.

While scientists have made great progress in the last few years, Baker says that are still large uncertainties in our emission estimates for the industry and our understanding of how they affect the atmosphere. “We hope that this work spurs further research to measure space industry emissions and highlights the need to regulate the geoengineering impacts of the space industry,” he says.

Team leader Eloise Marais, a professor of atmospheric chemistry and air quality at UCL, echoes this sentiment. “So far, there has been limited effort to effectively regulate this type of pollution,” she says.

The researchers are now working on an emissions tracker to visualize these emissions across the entire space age. “We are also using satellite imagery to remotely detect and quantify rocket launch emissions,” Barker reveals.

The post Soot from rocket launches is polluting Earth’s upper atmosphere appeared first on Physics World.

Planetary researchers have found the first evidence that bursts of energetic particles from the Sun could warm the lower atmosphere of Mars during massive dust storms, hinting at an unexpected link between space weather and Martian climate.

The post Space Weather May Warp Martian Weather during Dust Storms, Planetary Scientists Suggest appeared first on Sci.News: Breaking Science News.

Some of the most promising locations to search for possible alien megastructures, known as Dyson spheres, may not be stars like the Sun, but rather the galaxy’s smallest and dimmest stars.

Physicist Freeman Dyson introduced the idea of a Dyson sphere in 1960, describing it as a shell or, more realistically, a swarm of orbiting collectors that could capture most of a star’s energy. This concept has interested scientists searching for signs of advanced technology, but the question of how such a structure would appear in astronomical observations remained unknown.

Now, a new study, available on the arXiv preprint server, suggests that one of the coldest objects in a stellar system could, in principle, be an artificial megastructure rather than a natural astronomical object.

Amirnezam Amiri, a physicist at the University of Arkansas, explored the question of Dyson spheres by modeling these hypothetical megastructures around two often-overlooked types of stars: red M-dwarfs and white dwarfs. Amiri credits discussions with Harvard astronomer and founder of the Galileo Project, Avi Loeb, with helping shape the study.

Small, Dim, and Built to Last

Red dwarfs make up about 70% of the stars in the Milky Way. These stars burn slowly and can remain stable for trillions of years, much longer than the universe has even existed so far. White dwarfs offer a different benefit. As the dense remnants of stars like the Sun, they shrink to about 1% of their original size. This means a Dyson swarm could orbit much closer, requiring less material and a smaller structure than one built around a star like the Sun.

Amiri’s study explores how astronomers could detect such structures. Both red dwarfs and white dwarfs are dim enough that the infrared heat emitted by a Dyson swarm would stand out more clearly against the star’s own light.

Reading the Wreckage on a Star Chart

Astronomers use the Hertzsprung-Russell diagram to classify stars by temperature and brightness, and this tool is central to Amiri’s analysis. A Dyson swarm would not destroy a star’s energy, but would capture its light and re-emit it as heat at much longer wavelengths. 

In the new model, a star with a Dyson swarm would appear on the H-R diagram at the same luminosity but shifted dramatically toward the cool end. For instance, a red dwarf at about 3,000 K could appear surrounded by a shell as cold as 50 K, a difference of about two orders of magnitude. No known stars naturally occupy this region of the H-R diagram.

Identifying Factors

Dust and distant galaxies can also produce strong infrared emissions, so astronomers cannot identify a Dyson swarm using temperature alone. Amiri’s model points to a more complex set of clues. A true Dyson swarm would not show the silicate dust features seen in normal dusty disks, so its spectrum would be unusually smooth for an object with strong infrared emission.

Additionally, if the swarm consists of many separate collectors rather than a solid shell, there would be gaps that cause irregular, non-stellar flickering as the pieces move. Each of these signs can have natural causes, but finding them together is rare and hard to explain without considering artificial structures.

Future Observations

Astronomers can carry out this search using existing telescopes. The James Webb Space Telescope’s infrared instruments are already designed to detect faint, cold signals like these. The Vera C. Rubin Observatory’s new sky survey and the Nancy Grace Roman Space Telescope, which is expected to launch later this year, will add to these efforts. Together, they will generate the kinds of observations needed to search for the signatures described in the study.

Possible candidates for these future observations have already been identified. In 2024, Project Hephaistos identified seven potential Dyson sphere candidates among about 5 million cataloged stars, all linked to red dwarfs. One was ruled out after it was shown that a background black hole caused the observed signal. Several candidate Dyson sphere systems still remain under investigation. Amiri does not claim that any of these are actual Dyson spheres, and the paper makes this clear. Instead, the study offers a better way to tell true anomalies apart from dusty disks before using valuable telescope time. If a Dyson swarm surrounds a star and reradiates its energy at temperatures unlike those of natural stars, upcoming infrared surveys may finally be able to detect one.

Austin Burgess is a writer and researcher with a background in sales, marketing, and data analytics. He holds an MBA, a Bachelor of Science in Business Administration, and a data analytics certification. His work focuses on breaking scientific developments, with an emphasis on emerging biology, cognitive neuroscience, and archaeological discoveries.