7 ms·

Simply put no, 50MW is not the typical hyperscaler cloud size. It's not even the typical single datacenter size. A single AI rack consumes 60kW, and there is a

• tensor 8mo ago
  How much of that power is radiated as the radio waves it sends?
  • adgjlsfhk1 8mo ago
    the majority is likely in radio waves and the inter satellite laser communication
    • hdgvhicv 8mo ago
      Inter sat comms cancels out - every kw sent by one sat is received by another.
      • mlyle 8mo ago
        It doesn't, because the beams are not so tight that they all fall on the target satellite, and not all of that is absorbed :P
  • hirsin 8mo ago
    Good point - the comms satellites are not even "keeping" some of the energy, while a DC would. I _am_ now curious about the connection between bandwidth and wattage, but I'm willing to bet that less than 1% of the total energy dissipation on one of these DC satellites would be in the form of satellite-to-earth broadcast (keeping in mind that s2s broadcast would presumably be something of a wash).
    • adrian_b 8mo ago
      I am willing to bet that more than 10% of the electrical energy consumed by the satellite is converted into transmitted microwaves. There must be many power consumers in the satellite, e.g. radio receivers, lasers, computers and motors, where the consumed energy eventually is converted into heat, but the radio transmitter of a communication satellite must take a big fraction of the average consumed power. The radio transmitter itself has a great efficiency, much greater than 50%, possibly greater than 90%, so only a small fraction of the electrical power consumed by the transmitter is converted into heat and most is radiated in the microwave signal that goes to Earth's surface.
      • tullianus 8mo ago
        Unfortunately this is not the case. The amplifiers on the transmit-side phased arrays are about 10% efficient (perhaps 12% on a good day), but the amps represent only ~half the power consumption of the transmit phased arrays. The beamformers and processors are 0% efficient. The receive-side phased arrays are of course 0% efficient as well.
        • klaff 8mo ago
          I'm curious. I think the whole thing (space-based compute) is infeasible and stupid for a bunch of reasons, but even a class-A amplifier has a theoretical limit of 50% efficiency, and I thought we used class-C amplifiers (with practical efficiencies above 50%) in FM/FSK/etc. applications in which amplitude distortion can be filtered away. What makes these systems be down at 10%?
          • adrian_b 8mo ago
            Yes, a 10% efficiency is very weird if true. Nowadays such microwave power amplifiers should be made with gallium nitride transistors, which should allow better efficiencies than the ancient amplifiers using LDMOS or travelling-wave tubes, and even those had efficiencies over 50%. For beamformers, there have been research papers in recent years claiming a great reduction in losses, but presumably the Starlink satellites are still using some mature technology, with greater losses.
  • mlyle 8mo ago
    I doubt half the power is to the transmitter, and radio efficiency is poor -- 20% might be a good starting point.
    • synctext 8mo ago
      Is the SpaceX thin-foil cooling based on graphene real? Can experts check this out? "SmartIR’s graphene-based radiator launches on SpaceX Falcon 9" [1]. This could be the magic behind this bet on heat radiation through exotic material. Lot of blog posts say impossible, expensive, stock pump, etc. Could this be the underlying technology breakthrough? Along with avoiding complex self-assembly in space through decentralization (1 million AI constellation, laser-grid comms). [1] https://www.graphene-info.com/smartir-s-graphene-based-radiator-launches-spacex-falcon-9 https://www.graphene-info.com/smartir-s-graphene-based-radia...
      • ajnin 8mo ago
        This coating looks like it can selectively make parts of the satellite radiators or insulators, as to regulate temperature. But I don't think it can change the fundamental physics of radiating unwanted heat and that you can't do better than black body radiation.
        • synctext 8mo ago
          Indeed, graphene seems capable of .99 of black body radiation limit. Quote: "emissivity higher than 0.99 over a wide range of wavelengths". Article title "Perfect blackbody radiation from a graphene nanostructure" [1]. So several rolls of 10 x 50 meters graphene-coated aluminium foil could have significant cooling capability. No science-fiction needed anymore (see the 4km x 4km NVIDIA fantasy) [1] https://opg.optica.org/oe/fulltext.cfm?uri=oe-21-25-30964 https://opg.optica.org/oe/fulltext.cfm?uri=oe-21-25-30964
          • habinero 8mo ago
            It's not as exciting as you think it is. "emissivity higher than 0.99 over a wide range of wavelengths" is basically code for "it's, like, super black" The limiting factor isn't the emissivity, it's that you're having to rely on radiation as your only cooling mechanism. It's super slow and inefficient and it limits how much heat you can dissipate. Like the other person said, you can't do any better than blackbody radiation (emissivity=1).
  • nosianu 8mo ago
    The radio receiver and transmitter are additional hardware and energy consumption. They add to the heat, not subtract from it.
    • jeltz 8mo ago
      I think you missed the point. If you have a 100 MW communicstion satellite and a 100 MW compute satellite those are very different beasts. The first might send 50% of the energy away as radio communication making it effectively a 50 MW satellitefor cooling purposes.
      • habinero 8mo ago
        No, they didn't. You can't "send away" thermal energy via radio waves. At the temperatures we're talking about, thermal energy is in the infrared. That's blackbody radiation.
        • mortehu 8mo ago
          Your answer makes it seem like you too missed the point. If a Starlink sends a 1000W signal to Earth, that is 1000W of power that does not heat the satellite.
          • nosianu 8mo ago
            [flagged]
        • adrian_b 8mo ago
          You missed the point. Nobody describes a satellite by specifying the amount of heat that it produces, but by the amount of electrical energy that it consumes. In a communication satellite, a large fraction of the consumed electrical energy goes into the radio transmitter. Radio transmitters are very efficient and most of the consumed power is emitted as radio waves and only a very small part is converted into heat, which must be handled by the cooling system. So in any communication satellite, a significant fraction of the consumed energy does not become heat.
• lloeki 8mo ago
  For another reference, the Nvidia-OpenAI deal is reportedly 10GW worth of DC.
• pera 8mo ago
  New GPU dense racks are going up to 300kW, but I believe the normal at moment for hyperscalers is somewhere around ~150kW, can someone confirm? The energy demand of these DCs is monstrous, I seriously can't imagine something similar being deployed in orbit...
  • synctext 8mo ago
    Could this be about bypassing government regulation and taxation? Silkroad only needed a tiny server, not 150kW. The Outer Space Treaty (1967) has a loophole. If you launch from international waters (planned by SpaceX) and the equipment is not owned by a US-company or other legal entity there is significant legal ambiguity. This is Dogecoin with AI. Exploiting this accountability gap and creating a Grok AI plus free-speech platform in space sounds like a typical Elon endeavour.
    • habinero 8mo ago
      No. There is no "one weird trick" when it comes to regulation. The company is based in the US, therefore you just go after that. Anyway, promising some fantasy and never delivering is definitely a typical Elon endeavor.
    • jacquesm 8mo ago
      You misspelled 'hate speech'.
    • 9dev 8mo ago
      Untrue. Responsible for any spacefaring vessel is in all cases the state the entity operating the vessel is registered in. If it's not SpaceX directly but a shell company in Ecuador carrying out the launch, Ecuador will be completely responsible for anything happening with and around the vessel, period. There are no loopholes in this system.
    • Someone 8mo ago
      For the sake of an argument, let’s assume "The Outer Space Treaty (1967) has a loophole. If you launch from international waters (planned by SpaceX) and the equipment is not owned by a US-company or other legal entity there is significant legal ambiguity” is 100% true. To use that loophole, the rockets launched by SpaceX would have to be “not owned by a US-company”. Do you think the US government would allow that to happen?
• mike_hearn 8mo ago
  But the focus on building giant monolithic datacenters comes from the practicalities of ground based construction. There are huge overheads involved with obtaining permits, grid connections, leveling land, pouring concrete foundations, building roads and increasingly often now, building a power plant on site. So it makes sense to amortize these overheads by building massive facilities, which is why they get so big. That doesn't mean you need a gigawatt of power before achieving anything useful. For training, maybe, but not for inference which scales horizontally. With satellites you need an orbital slot and launch time, and I honestly don't know how hard it is to get those, but space is pretty big and the only reasons for denying them would be safety. Once those are obtained done you can make satellite inferencing cubes in a factory and just keep launching them on a cadence. I also strongly suspect, given some background reading, that radiator tech is very far from optimized. Most stuff we put into space so far just doesn't have big cooling needs, so there wasn't a market for advanced space radiator tech. If now there is, there's probably a lot of low hanging fruit (droplet radiators maybe).
  • cogman10 8mo ago
    > I also strongly suspect, given some background reading, that radiator tech is very far from optimized. Most stuff we put into space so far just doesn't have big cooling needs, so there wasn't a market for advanced space radiator tech. If now there is, there's probably a lot of low hanging fruit (droplet radiators maybe). You'd be wrong. There's a huge incentive to optimized radiator tech because of things like the international space station and MIR. It's a huge part of the deployment due to life having pretty narrow thermal bands. The added cost to deploy that tech also incentivizes hyper optimization. Making bigger structures doesn't make that problem easier. Fun fact, heat pipes were invented by NASA in the 60s to help address this very problem.
    • mike_hearn 8mo ago
      The ISS is a government project that's heading towards EOL, it has no incentive to heavily optimize anything because the people who built it don't get rich by doing so. SpaceX is what optimization looks like, not the ISS.