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Cake day: March 22nd, 2024

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  • That’s interesting, but what’s the point? If it’s like 2 DGX boxes in each satellite, spaced out, the interconnect between them is going to be very slow, and the individual computational power of each satellite will not be that impressive.

    And if you connect them all in one constructed mesh and wire them together, well, you’ve made a 200MW datacenter! The economies remain the same.

    If hardware gets more power efficient, well… Then why do you need to go to space anymore?


  • 100kW? Nvidia BGX 200 servers are 14kW each, not counting the interconnect, or anything else. According to nuggets I’ve read online, we’re talking 200 megawatts for an Earth-based AI datacenter these days, without something exotic like underclocked Cerebras WSEs (which would be pretty neat, actually…)

    Plugging 200 megawatts into this:

    https://www.calctool.org/quantum-mechanics/stefan-boltzmann-law

    I get about 0.46 square kilometers, depending on the coolant temperature, and ultimate efficiency of the system (with how you orient the thing relative to solar panels, how you circulate coolant…)

    I have no clue what the construction of such a huge structure would look like, but if it was a simple 0.5 inch aluminum sheet, it would weigh like 15,000 metric tons. Even much thinner, that’s still on the order of “mass of a cargo ship”


    Why is that, though?

    Well, something like the ISS doesn’t generate much heat, and hypothetical rockets that need big radiators have very hot coolant to dissipate heat quickly. But space data centers are the sinister combination of “tons of waste heat” and “needs a low coolant temperature.”




  • On radiators, plugging it into this formula:

    https://projectrho.com/public_html/rocket/heatrad.php

    I get a circular radiator at least a kilometer wide, assuming the radiator is quite efficient, a rather modest datacenter, and very hot coolant (70C).

    …Realistically, the coolant temperature would need to be much lower. See how it’s a power of four in the formula? That means the radiator area gets very large real quick.

    I cannot emphasize how expensive a functional 1km+ radiator would be in space. It’s mind bogglingly expensive.


    If a space datacenter is in LEO like Starlink, then it’s in Earth’s shadow a lot of the time, and would have to be “part” of the starlink network constantly zooming over the ground. If it’s geosynchronous, then laser communication (or any communication) gets real tricky, and latency is limited by the speed of light. I’m not saying it’s impossible, but reliable high data rates would be an expensive engineering challenge.