Status: Operational in LEO. Demonstrator / proof-of-concept, not commercial. Validated the in-orbit-AI training thesis that the Series A is now funding at scale.
Hardware
- GPU: Single commercial NVIDIA H100 SXM (80 GB HBM3, ~4 PFLOPS FP8 AI throughput per chip — "100× more powerful than any GPU ever operated in space") [377][378][379]
- Bus: PCIe Gen5 to the host CPU; the H100 runs as an inference + training accelerator with the CPU doing the housekeeping / IO
- Mass: ~60 kg total spacecraft ("size of a small refrigerator") [377][378]
- Form factor: 6U-ish smallsat-style platform (not a cubesat — the H100's thermal envelope needs a dedicated radiator; the chassis is a custom silver-anodised module that doubles as the radiative cooler)
- Cost: Built in 21 months on $3M pre-seed [380] — i.e. the entire demonstrator was funded with one pre-seed check, before the $24M seed and $170M Series A
- Launch: November 2, 2025, on a SpaceX rideshare (Falcon 9) [4][5]
What it proved (December 2025)
- First LLM training in orbit — Starcloud-1 ran Andrej Karpathy's nano-GPT end-to-end on-orbit in December 2025, becoming the first spacecraft ever to train an LLM [5][376]
- First Google Gemini-family model run in orbit — Ran a version of Gemini (per Starcloud's marketing [376]; some technical press identifies the actual model as Google's open-source Gemma family, derived from Gemini [378][379]) on the H100 in space [376][381]
- 100× compute uplift — Brought orbital AI compute from the previous state-of-the-art (radiation-hardened DSPs and small FPGAs) to data-center-class in one satellite [377][378][379]
- Radiative cooling works — Validated that the deep-space heat sink can dissipate H100-class thermal envelopes without water or evaporative towers (NVIDIA Blog notes "instead of relying on fresh water for cooling through evaporation towers... Starcloud's space-based data centers" use radiative cooling) [4]
Endorsements
The December 2025 result drew public statements from:
- Eric Schmidt (former Google CEO) — public endorsement cited on Starcloud's own Starcloud-1 page [376]
- Andrej Karpathy (former Tesla AI director, OpenAI co-founder) — quoted on the nano-GPT result; the choice of his nano-GPT as the validation model is itself a credibility signal [376]
- Demis Hassabis (Google DeepMind CEO) — public endorsement cited on the Starcloud-1 page [376]
Why the H100 (not a radiation-hardened chip)?
The counter-intuitive bet is that a commercial terrestrial H100 with software-level radiation mitigation (ECC, scrubbing, checkpoint-restart) is cheaper and faster than a rad-hardened space chip. The physics argument:
- Terrestrial H100: 4 PFLOPS, $30K/chip, ~700 W TDP. Software mitigation via frequent checkpointing to storage; a SEU in flight means rolling back to the last checkpoint.
- Rad-hardened space chip: ~10 GFLOPS, $5M+ per chip, ~50 W TDP. ~400× less compute per dollar per watt.
For training workloads where the loss function is dominated by gradient noise anyway, SEU-driven rollbacks are absorbed into the training loop at the cost of a few percent throughput — vastly cheaper than 400× less compute per chip. Starcloud-1's December 2025 result is the first in-orbit proof of this thesis.