The Impact of Computing Data Centres Orbiting Earth
Artificial intelligence is projected to increase U.S. data centre power demand beyond 100 gigawatt by 2035 and global demand toward 1 terrawatt. In response, companies and governments have proposed placing computing infrastructure in sun-synchronous low-Earth orbit, where continuous sunlight could supply electrical power. Generating 5 GW would require solar arrays 4 x 4 kilometers in size. Although technically feasible, such structures at roughly 500 km altitude would dramatically alter both the night and daytime sky. A 4 x 4 km array in low earth orbit would span about 0.4 degrees, comparable to the Moon, and reflected sunlight would make it shine at magnitude g = -5 to -7 mag, 100 times brighter than the brightest stars. Dozens of these structures would appear as a north-to-south chain of industrial objects across the sky, visible for about 1 1/2 hours after sunset and 1 1/2 hours before sunrise. They would block stars, planets, and deep-sky objects for minutes at a time, while increasing the likelihood of collisions that could trigger runaway debris production. These orbiting computing facilities therefore pose serious astronomical, technical, and cultural concerns.