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The Case for Data Centers in Space

2026-08-05 · 14:00 UTC ·Y Combinator ·1 min read

Brief

Starcloud CEO Philip Johnston (interview) recounts launching an Nvidia H100 into orbit in Nov 2025 and training an LLM there, the company's origin and rapid fundraising, and the engineering fixes for heat and radiation (particle‑accelerator testing, unconventional cooling, automotive parts). He outlines FCC filings for 88,000 satellites and plans to scale to ~20 GW of space power.

Why it matters

In November 2025 Starcloud launched an Nvidia H100 GPU into orbit and trained the first large language model in space.

Key details

  • Starcloud raised $200 million and hit a $1 billion valuation 17 months after YC demo day; they filed with the FCC to deploy 88,000 satellites and plan a path toward ~20 gigawatts of space-based power.
  • The two hardest engineering challenges were heat and radiation: they cooled an H100 with an improvised ice-bath test, validated GPUs in a particle accelerator, used automotive-grade components where possible, and are co-designing a space-optimized GPU with NVIDIA.
Source evidence

Philip Johnston is the co-founder and CEO of Starcloud, the company building data centers in space. In November 2025, Starcloud launched an Nvidia H100 GPU into orbit and trained the first large language model in space. They've since raised $200 million, hit a billion-dollar valuation just 17 months after YC demo day and filed with the FCC to deploy 88,000 more satellites. In this episode, Philip walks us through their wild origin story, the engineering challenges behind the Starcloud-1, why they booked a SpaceX launch before they even knew what they were building and how data centers in space make sense both economically and politically.

Transcript: https://www.ycrootaccess.com/p/starcloud-solving-ais-energy-problem

Chapters:
00:00 - First thing every space company should do
01:06 - Why data centers in space
01:35 - The Starbase trip that started it
02:53 - Asteroid mining, space hotels, and the ideas they passed on
03:20 - Why space-based solar doesn't work
04:38 - Launching Starcloud-1
05:35 - Cooling an H100 in an ice bath at 5AM
06:24 - The separation video
07:15 - First contact and the satellite that kept restarting
09:42 - The two hardest problems: heat and radiation
11:27 - Testing GPUs in a particle accelerator
12:49 - Automotive parts instead of space-grade
13:55 - "The dumbest thing I've ever heard"
14:30 - What 100 VCs got wrong
18:38 - The path to 20 gigawatts in space
20:31 - First customers
21:16 - Designing a GPU for space with NVIDIA
23:09 - A Bitcoin miner in orbit
24:00 - Why hard tech suddenly got popular with VCs
25:37 - Inside the Benchmark round
26:57 - Their hiring strategy
28:08 - How to be contrarian but right
30:49 - Recruiting co-founders before having an idea
31:44 - What if data centers get banned on Earth?
32:45 - Data center myth busting
35:09 - Advice for hard tech founders

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Channel: Y Combinator
Published: 2026-08-05
Video URL: https://www.youtube.com/watch?v=A9JDkiYEhfY