March 12, 2026 — 5:00pm Save The energy vampire next door: Life next to an AI mega-factory That provided valuable data on the reliability of AI chips under orbital conditions. The company also has a good handle on the other crucial figures. Stats of play Start with specific power. McCalip’s figure of 37W/kg comes from the thousands of satellites used in SpaceX’s Starlink constellation, thought to be state of the art, which provide high-speed internet to users around the world. Advertisement But Starlink satellites have to do things that AI satellites do not. They need costly “phased-array” antennas to communicate with the ground, and must have a stable orientation at all times. AI satellites, by contrast, would not need to communicate with the ground—only with their neighbours, using laser links. They would, therefore, be able to devote much more of their mass to delivering processing power. And without the need for such accurate pointing, they could have solar panels that are slightly flexible, reducing their mass and further boosting specific power. Musk has said that he thinks a specific power of 100W/kg is feasible for an AI satellite, and some believe that by using more efficient solar cells even 150W/kg may be possible in future. Is it feasible? SpaceX proposes that the sun - shown here during a geomagnetic storm watch last year - would directly power the data centres in space. NASA/AP Philip Johnston, Starcloud’s boss, says his firm is aiming for a specific power of 70W/kg for its forthcoming satellites, based on what it considers to be quite conservative assumptions. Advertisement Moving on to satellite cost, Johnston says Starcloud expects its design to cost “less than $US5 per watt” when GPU costs are excluded. McCalip estimates that Starlink’s current satellites cost around $US22/W, down from $US32/W for its original version. Again, an AI satellite should cost less to build, GPUs aside, because it does not require costly communications components. Move the sliders on McCalip’s calculator to a specific power of 70W/kg and a satellite cost of $US5/W, and the numbers look rather different: now the 1GW orbital data centre costs $US16.7 billion, only 5 per cent more than the terrestrial one. A number of optimistic assumptions are needed to get there. First, a launch price of $US500/kg, roughly a third of what is available today. But, if SpaceX’s new Starship rocket starts working, launch costs could fall fast. Because Starship is designed to be fully reusable, the price of sending a kilogram into orbit could drop to $US100 to $US200, says Johnston. (The actual cost to SpaceX would be much less; possibly as low as $US20/kg.) Put a launch price of $US200/kg into McCalip’s calculator, and the cost of the 1 gigawatt orbital data centre drops to $US12 billion—less than the terrestrial one. The idea, in short, may not be quite as crazy as it looks. Advertisement Another unknown is cooling. Starcloud’s initial satellite could not run its GPU round the clock because (as expected) it got too hot. The firm plans to launch a second test satellite, Starcloud-2, this year to evaluate its design for an unfolding radiator, to provide cooling. Johnston says it will be “the largest commercial deployable radiator in space”, second in size only to the radiator on the International Space Station, but providing 10 times as much heat dissipation per kilogram. Starcloud’s cost estimates assume that this radiator will work as planned. Other assumptions may be too pessimistic. For one, McCalip’s calculator assumes that as many as 9 per cent of GPUs launched into orbit will fail every year. But one lesson from Starcloud-1, says Johnston, is that “GPUs work better in space than we had expected.” He is reluctant to share the exact figures. But if only 5 per cent of GPUs fail each year, fewer satellites would be needed, and the cost of the orbital data centre would drop to $US11.1 billion. Related Article