Thread

1. zactato · 1790267254 · focus · HN ↗

   How are they solving the heat dissipation issues?

   1. lopsotronic · 1790268994 · 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. xur17 · 1790281214 · focus · HN ↗

         > 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.

         We need > 2x more solar panels than we need radiators. Doesn't this imply radiation isn't really the limiting factor here?

         1. rayiner · 1790281440 · focus · HN ↗

            It’s obvious that radiation isn’t the limiting factor, since, as you note, there’s no reason a satellite shouldn’t be able to radiate at least as fast as it gets power from the sun. I don’t know how this became a meme.

            1. xur17 · 1790313840 · focus · HN ↗

               Yeah, I suppose another way to look at it is that ALL satellites have to radiate the energy they get from the sun (since 99+% of electricity used by electronics gets radiated off as heat). A datacenter is no different. All that is different is that quantity of energy both in and out, the ratios are identical.
         2. snovv_crash · 1790282168 · focus · HN ↗

            Getting the energy back from the solar panel is easy via copper cables. Getting the heat back out there to the radiators is a bit harder, you needed fluids and pumps and heat exchangers which have lots of moving parts and need maintenance.

            1. alexnewman · 1790284594 · focus · HN ↗

               This has all been covered over and over again. It’s actually not that big of a deal

               1. datadrivenangel · 1790288281 · focus · HN ↗

                  Doing it in a cost and weight effective way is still a big deal, because if it's not within ~10x the cost of ground based data centers, not enough people will use it to justify building it.

                  1. scottyah · 1790292478 · focus · HN ↗

                     ...but they are already building it.

                     1. jasonwatkinspdx · 1790300543 · focus · HN ↗

                        Ah yes, the same way they built us all solar roof tiles.

                        1. scottyah · 1790354400 · focus · HN ↗

                           I really hope those get an improvement, the externalities of asphalt roofs are so crazy I wish more people paid attention.

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