Why AI's environmental footprint won't disappear into orbit Sadie Harley Scientific Editor Andrew Zinin Chief Editor AI companies increasingly want to move their operations into space. Elon Musk's SpaceX has applied to launch over a million AI data center satellites and ultimately build them on the moon. Jeff Bezos, Google, OpenAI and others have similar plans.

The idea is to harness 24/7 solar energy and, in Bezos's vision at least, to move all polluting industries off-world, rezoning Earth for humans and nature. It's an intriguing plan. But once you factor in the whole life cycle, from water and rocket fuel used to launch these satellites into space to keeping them cool and eventually disposing of old satellites, the environmental case becomes less clear.

Outer space, out of mind Off-worlding polluting industries is not a new idea. In the 1970s, when the last Iranian oil crisis caused rocketing fuel prices, NASA kicked off a plan to build huge solar plants in space. The idea flopped when the oil began to flow again.

NASA also explored the prospect of storing nuclear materials on the moon and blasting hazardous waste at the sun. These plans may have been feasible from an engineering perspective but were politically impossible because of the risk of radioactive particles eventually falling back to Earth. Since data centers need so much energy, much of it for AI, such astronomical ideas are back on the table.

Regular Earth-based data centers were responsible for around 5% of all electricity used in the U.S. last year, for instance, mostly using fossil fuels. Their share of U.S.

power demand will likely triple by 2028. The fragile frontier That's why the cold vacuum of space, with its endless supply of solar energy, is being pitched as a more sustainable alternative to big, noisy, hot data centers in our backyards. Meanwhile, a recent petition from environmental law charity Earthjustice is calling for a comprehensive review.

They argue these proposals fail to acknowledge any environmental impact. "This is not just poor planning and a missed opportunity," the petition states, "it violates federal law." Indeed, SpaceX's planning applications come with assurances of no meaningful environmental impact. "It's always sunny in space," according to Musk, who says orbital data centers are "obviously the only way to scale." Yet data centers in space would be even more prone to overheating than those on Earth.

That's because, like a Thermos flask, space keeps things hot. There's no water or air to carry excess heat away. Instead, keeping powerful AI chips cool in orbit requires massive ammonia-filled radiators that let heat escape as infrared radiation.

This isn't very efficient, and those radiators are much larger than the computers they cool. Lifting these huge structures to orbit would require a lot of rocket fuel. Most plans for orbital data centers depend on the future success of SpaceX's heavy-lift Starship.

But every Starship launch burns over 1,000 metric tons of liquid methane, releasing around 80,000 metric tons of CO₂ (about the same as 20,000 cars emit in a year). The warming associated with soot emissions in the upper atmosphere is 500 times more intense than the same emissions at ground level.