Plans are afoot to launch large mega-constellations of AI data centres into Earth orbit. That ambition, pursued by multiple space industry leaders, coincides with a warning from scientists of potentially “catastrophic outcomes,” as the likelihood of satellite collisions in orbit increases.
If all the satellites currently in low Earth orbit were suddenly unable to manoeuvre to avoid each other — a problem that could be triggered by a massive solar storm — then a potentially catastrophic collision would likely occur in just under four days, researchers say.
That’s the latest finding from the CRASH Clock, a tool developed to monitor the timeframe during which a low Earth orbit satellite collision is likely to happen during a major solar event. Such events are difficult to predict and come with limited warning; solar activity peaks roughly every 11 years. The CRASH Clock assesses the sustainability of space operations, explains Sarah Thiele, first author on the paper and a PhD student at Princeton University.
“The paper demonstrates how reliant we are on the continuous successful active management of satellites in orbit, and how the margin for error in these operations is decreasing over time,” she writes in an email to Mongabay.
In 2018, the CRASH estimate stood at a comfortable 164 days. But that margin of safety shrank rapidly as the proliferation of satellites surged, and was shortened to 5.5 days by June 2025, while a calculation using orbital data from January 2026 cut it to 3.8 days.
“This just shows how reliant we are on perfect operations in orbit,” Thiele writes. The outcomes of a collision could range from a few satellites being knocked out of commission to larger-scale destruction or even triggering a chain reaction as fragments hit and destroy others.
This troubling orbit collision projection coincidentally coincides with announced plans to launch hundreds of thousands of new satellites to feed growing demand for AI data centres in space — which is not a pie in the sky sort of plan.
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The number and distribution of active satellites in orbit need to be better regulated. Right now [low Earth orbit] is largely a Wild West due to regulation lagging behind its rapid commercialisation.
Sarah Thiele, researcher, Princeton University
Major players in the space industry, including SpaceX, Google, Blue Origin, the Chinese space program and the EU space program, are aggressively looking to space as a means of boosting computing power while also sidestepping the community resistance and environmental problems arising from terrestrial data centre proposals.
Google, through Project Suncatcher, aims to commence tests as early as next year. Elon Musk’s SpaceX is seeking approval from the US Federal Communications Commission to launch up to 1 million satellites to build an orbital data centre.
“Having a million satellites is completely unsafe for collisions,” says Samantha Lawler, a co-author on the CRASH study and an astronomer at the University of Regina in Canada. But, she adds, launching AI data centres into space is just one facet of an incredible surge in traffic as the public and private space industry grow at light speed with little regulation or environmental oversight.
“Satellites have a huge environmental footprint. We’re just ignoring it,” Lawler says.
The addition of countless AI data center vehicles will up the statistical chances for catastrophic collisions, with some scientists warning that multiple satellites crashing into each other and fragmenting could theoretically result in an ongoing chain reaction of collisions at 18,000 miles per hour, a consequence known as the Kessler Syndrome — threatening the operation of vital low Earth orbit communication, weather, transportation, defense and research satellites and potentially impacting modern civilisation in unimaginable ways.
A hunk of burning satellite falls from the sky
Around 14,000 active satellites currently orbit Earth, alongside several thousand pieces of space junk. By some estimates, the number of satellites could grow to more than 60,000 or even above 500,000 by 2040, though those estimates were made before orbiting data centre plans were announced.
But what goes up must come down — which means pollution, potentially lots of it.
When satellites and other spacecraft debris burn up, they release aluminium oxide and other metals and elements, which can eventually contaminate the atmosphere, land and water.
There are three main risks associated with this pollution, explains John Plane, professor of atmospheric chemistry at the University of Leeds in England: Changing the Earth’s radiative balance, harming the ozone layer and releasing toxic elements, such as mercury and cadmium, which can rain down and pollute freshwater ecosystems.
A 2025 paper found there may be enough alumina deposited in the stratosphere by satellites by 2040 to alter wind speeds in Earth’s polar regions, increase temperatures in the mesosphere (50-85 kilometres or 30-50 miles above the planet’s surface), and damage the ozone layer. That’s based on a volume of space junk falling from the sky equivalent to around 150 space shuttles burning up in the atmosphere every year.
Adding AI data centres, and thousands of other satellite types, to this orbiting traffic jam will not only greatly increase the volume of reentries over time, but also possibly introduce new pollutants with unknown effects, experts say. Data centres operate using tens of thousands of microchips, which contain multiple toxic substances, including PFAS forever chemicals.
“When one breaks down the currently used materials [in orbital vehicles] into their chemical elements, we found that today, 24 elements are dominating over the atmospheric injection from meteoroids,” Leonard Schulz, geophysicist at the Technical University of Braunschweig in Germany, writes in an email. “A lot of them are transition metals like copper, titanium, or niobium, which are known to be great catalysts in chemical reactions, meaning small amounts could be sufficient to induce measurable changes in the atmosphere.”
Researchers are only just initiating studies to explore how these elements introduced by space launches and reentries are affecting the atmosphere.
“The more satellites put into orbit, the more impacts on the atmosphere one can expect,” Schulz says. “Unfortunately, it’s just too early to tell what the exact impacts are.”
“We are already able to detect the effect of our current level of space activities in Earth’s atmosphere,” adds Robin Wing, at the Leibniz Institute of Atmospheric Physics in Germany.
His team recently tracked a large plume of lithium in the atmosphere and traced it back to a SpaceX Falcon 9 rocket burning up upon reentry. “I think there’s sufficient evidence to be concerned and we should do the work of making measurements now and into the future to see if there are long-term trends.”
Unlike past unforeseen environmental crises — as occurred with the DDT pesticide in the 1960s or the current problems with PFAS forever chemicals — scientists are trying to use the precautionary principal to predict and prevent harm before it happens, even as big tech companies and governmental programs rush into space.
Not so clear trade-offs
Back on Earth, AI data centres already have a massive, ever-growing footprint. Often built in dry climates, they consume huge amounts of water, while sucking up every kind of energy (including oil, gas and renewables) and generating a range of pollutants, including greenhouse gases. Launching such facilities into space is unlikely to be a panacea for these Earth-bound ills, experts say.
“Data centres are [likely] doing some pretty terrible things to the Earth,” notes Ann Thresher, an assistant professor at Northeastern University; in her view, the purported benefits of launching these facilities into space are far from clear-cut.
“There’s much less nuanced conversation about the actual environmental cost of putting things in space, maintaining them and decommissioning them, which is very extensive and not well understood at this point,” she says.
The rapidly growing space industry already has a large environmental footprint. Sending a rocket into space is heavily polluting, emitting greenhouse gases, black carbon (known as soot, a major particulate pollutant and public health hazard), while also potentially damaging the ozone layer as launch numbers escalate.
Spaceports, meanwhile, tend to be sited around the equator and near coastlines, abutting biodiversity-rich regions and often protected areas with the potential to cause tropical deforestation and harm to endangered species. The Cape Kennedy spaceport is already known to have contributed to global species extinction, helping send the Dusky seaside sparrow (Ammodramus maritimus nigrescens) into oblivion.
A major issue today revolves around the lack of regulation space activities. For Lawler, that’s exemplified by Reflect Orbital, a US startup that plans to launch satellites able to beam sunlight to Earth, providing sunlight “on demand” to power solar panels, provide streetlighting and more. It’s an idea causing concern among scientists.
“A million satellites is a ridiculous number, but even one satellite can have huge effects on astronomy and on ecology,” Lawler says.
“The number and distribution of active satellites in orbit need to be better regulated. Right now [low Earth orbit] is largely a Wild West due to regulation lagging behind its rapid commercialisation,” Thiele says.
Researchers argue that a thorough understanding of the sustainable use of Earth orbit needs to happen before any further massive deployment of satellites. “I think this shouldn’t happen until we have a very clear idea of how much space activity the atmosphere can tolerate without affecting the ozone layer and also the radiative balance,” Plane says. Impacting the incoming energy from the sun and outgoing energy from Earth could have unknown impacts on the planet’s already destabilised climate.
“I don’t want to say that we shouldn’t be doing data centres in space,” Thresher says, yet she agrees there needs to be a thorough assessment of the environmental impact of plans to do so. “We can’t sacrifice the Earth in the pursuit of space.”
This story was published with permission from Mongabay.com.
