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Google’s Project Suncatcher to put ML infrastructure in space

233 points · 553 comments · xnx

  1. zactato · · focus · HN ↗
    How are they solving the heat dissipation issues?
    1. lopsotronic · · focus · HN ↗
      For real. It's an enormous problem solved only with 1) sheer scale, and 2) Science Fiction.

      Both of those are expensive as hell, by the way.

      Cooling via radiation follows Stefan–Boltzmann: P = εσAT⁴. Let's assume a good surface (emissivity ~0.9) at 300 K (27 °C) at 400 W per square meter per side. A flat panel radiating from both faces into deep space gets 800 W/m, not including the losses from, say, the Sun, or from IR coming off the Earth. Now, input power. Sunlight in orbit ~1,360 W/m², assume ~22% cell efficiency, we got 300 W/m². So each 1 MW compute, 3,300 m² of solar panel and minimum 1,200–1,500 m² of radiator.

      In case ya didn't know - 1 MW is tiny from a present-day-datacenter perspective. It's like 8 racks. So we're talking orbital megastructures here, many many many square kilometers, and this is with all the best case assumptions, and magic radiator panels that never see the sun, or the earth, or the moon.

      This is just the basic numbers here, by the way. There's a garbage truck full of other unsolvable problems if you poke your head in there.

      Aside from the "Avoid Regulations" aspect, and the "Everything That Burns Deorbiting is Depreciation" aka "The Starlink Trick", I'm not sure what the hell the draw is.

      1. SyzygyRhythm · · focus · HN ↗
        No point in running them at room temperature. GPUs, etc. run fine at 95 C. If you run your cooling loop at 70 C instead, you get 70% more cooling compared to 27 C.

        At any rate, 1 MW for a single satellite is fine. Just launch several thousand of those and you get to real numbers.

        Also, there's no need to talk about "magic" radiators. You orient them so they're at a knife edge to both the Sun and Earth. This is not difficult (the Moon is irrelevant).

        1. octoberfranklin · · focus · HN ↗
          No point in running them at room temperature. GPUs, etc. run fine at 95 C.

          They run fine for a short while, but not nearly as long.

          Heat accelerates all aging processes. It's how they artificially age chips in order to calculate MTBF.

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