Elon Musk’s talk about maintaining a million-strong AI data center satellite megaconstellation may not exactly be practical or economical, but it might be unique. It’s about the closest we’ve come to confronting a scheme that would export a considerable amount of valuable materials into space. Humans aren’t doing a great job of material sustainability, but normally we’re talking about stuff escaping a recycling pipeline rather than escaping Earth’s gravitational pull.

The commercial space sector likes talking about the allure of mining asteroids for precious metals to bring back to Earth. Under what circumstances are we going to be willing to do that in reverse? Starlink alone has doubled the mass of objects in low-Earth orbit, and this orbital data center constellation would dwarf that—and dispose of at least some satellites by pushing them away from Earth.

Given the roughly five-year expected lifetime for data center GPUs, about 200,000 of the 1 million proposed SpaceX AI1 satellites would be decommissioned each year. Based on their May 29 FCC filing, about 40,000 would definitely deorbit and burn up in the atmosphere. (Those materials would largely be dispersed throughout the atmosphere, turning a resource into a diffuse contaminant that slowly settles over the globe. One related issue: the aluminum would cause an unknown amount of ozone depletion over a period of decades.) Some or all of the remaining 160,000 satellites would be moved outward into a distant “disposal” orbit, instead. Either way, they're lost from a "material life cycle" point of view.

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Global warming is leading to more extremely hot weather. There is perhaps no more obvious consequence of climate change. But changing how we analyze this problem can still help scientists think about it in a different way that may yield surprises.

Generally, studies on heat extremes work with some combination of daily minimum, maximum, and mean temperatures. Sometimes they focus on multi-day heatwaves using those metrics, since the discomfort and health impacts increase for longer events. There are different thresholds you can use to define extreme heat in these analyses, either based on past statistics or on the human body’s physiological limits.

A new study led by Weilin Liao and Xuanzong Zhang at Sun Yat-sen University tried breaking down heat extremes to the hourly level instead, which reveals some interesting nuances.

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While recycling is a mathematically obvious response to the finite, non-renewable nature of many resources, the economic math is often challenging. For many materials, it can be hard to compete with virgin materials on a cost basis. Fast-moving technologies like electric vehicles throw in an added complication: By the time a car is scrapped, the industry may have moved on to a different battery chemistry. That reduces the value of recycling the car’s battery back into the production chain.

Still, a study led by Xin Xiong at Nanjing University finds that in China, recycling could become the dominant source of many key materials needed to manufacture EV components over the coming decades.

Modeling manufacturing needs

The researchers set out to model how the supply of recycled materials compares to manufacturing demand in China between 2010 and 2050. It covers materials relevant to batteries across hybrid, battery-electric, and even fuel-cell vehicles (lithium, cobalt, nickel, manganese, phosphorus, sodium, sulfur, and graphite), as well as several critical elements used in electric motors (copper, neodymium, dysprosium, samarium, and cerium).

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