Inside The Startup Launching AI Data Centers Into Space

StarCloud aims to start by providing GPU compute to other satellites, then build larger orbital facilities. Johnston says constant sunlight could supply power, while radiators would release heat into space without using fresh water. He argues this could reduce pressure on Earth’s electricity grids and water supplies.

Johnston studied applied math and theoretical physics and began his career in software. His team first explored space-based solar power, but estimated launch costs would need to fall to about $50 per kilogram for the idea to break even. After accounting for energy lost when beaming power to Earth, they shifted to sending data centers into orbit, with an estimated break-even launch cost of $500 per kilogram.

StarCloud says it designed, built, and tested its first satellite in 15 months. The roughly 60-kilogram spacecraft carries an NVIDIA H100, and the team built its compute module, antennas, power system, and thermal hardware in-house while contracting Astro Digital to make the satellite bus. Johnston identifies radiation shielding and a deployable radiator as key engineering challenges.

StarCloud joined Y Combinator in summer 2024, after three application attempts, under the name Lumen Orbit. Johnston says YC encouraged the founders to discuss the larger ambition of serving data centers beyond satellite customers. Co-founder Addi brings data center and SpaceX software experience, while CTO Ezra has a decade of satellite design experience and a PhD in engineering.

Starcloud-1 launched on November 2 with the first NVIDIA H100 deployed in space. The company planned tests including model training, inference, and running Gemini, though the transcript describes these as future demonstrations. Johnston says a planned second satellite would have at least ten times the first satellite’s capability, use NVIDIA Blackwell GPUs, and add high-bandwidth optical links.