Haral Tsitsivas 🇺🇸🦅🇬🇷🇺🇦 haral.bsky.social

Google put an AI computer in outer space, and it has to shut itself off about every 15 minutes because it's overheating. Outer space is around minus 455 degrees Fahrenheit, so that sounds backwards, but the emptiness that makes space so cold is the same thing cooking the chips. Think about how your laptop stays cool. A little fan blows air over the chip and the air carries the heat away. Big data centers do the same thing on a massive scale, with water pipes running out to cooling towers. All of it works because there's air and water around to soak up the heat. Up in orbit there's basically nothing. A vacuum is one of the best insulators there is, which is the whole reason your thermos keeps coffee hot all day. So the only way a satellite can get rid of heat is to glow it off. Anything warm gives off infrared light, you just can't see it, and in space that faint glow is the one way out. A physicist named Josef Stefan worked out the math back in 1879. The heat a surface throws off goes up with the fourth power of its temperature, so if you double the absolute temperature it sheds 16 times as much. And while all this is happening, the sun is beating down on the other side of the satellite. Google's test satellite is about the size of a fridge. It has four of Google's AI chips on board and solar panels that make around one kilowatt, roughly what your microwave pulls. Even on that little power, the chips can't run nonstop. They work for about 15 minutes, then shut off and wait for the radiators to catch up. The haiku Sundar posted came out of one of those runs. Now scale that up to what a real AI data center runs on. One rack of Nvidia's GB200 servers pulls about 120 kilowatts, and pretty much all of it turns into heat. The International Space Station cools itself with six radiators, each about 76 feet long, and the whole system can dump 70 kilowatts. So one rack of AI servers puts out almost twice the heat the entire space station was built to get rid of. Google's long-range plan has around 80 satellites flying in a cluster about a kilometer wide, some only 100 to 200 meters apart, each one loaded with dozens of chips. A solar panel in the right orbit makes up to 8 times the power it would on the ground, and every one of those extra watts eventually becomes heat the satellite has to glow back out into space. SpaceX has filed for a million satellites of its own, and Starship keeps pushing the price of a launch down. Cheaper launches mean you can afford to send up bigger radiators, and whoever builds the lightest radiator that dumps the most heat is going to own AI in orbit. For now, the satellite in Sundar's video still has to stop and cool down every 15 minutes or so.