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Google’s Project Suncatcher to put ML infrastructure in space

233 points · 553 comments · xnx

zactato · 1790267254 · focus · HN ↗
How are they solving the heat dissipation issues?
1. GMoromisato · 1790270501 · focus · HN ↗
  Please stop with this argument. This is one of the easiest problems to solve. Heat dissipation requires a radiator, which is just a dumb hunk of metal. All you need is a cheap way to launch mass to orbit, which is exactly what SpaceX (and Chinese companies) are doing.
  The only valid argument against data centers in space is the economic cost. If the per megatoken price for space datacenters is higher than terrestrial, then this won't work.
  But the price for terrestrial datacenters keeps going up and technology keeps dropping the price of space-based.
  1. devmor · 1790273034 · focus · HN ↗
    > Please stop with this argument. This is one of the easiest problems to solve. Heat dissipation requires a radiator, which is just a dumb hunk of metal.
    Convective radiation does not happen in space and this challenge is far more significant than your comment implies. Rather than "a dumb hunk of metal", radiators for spacecraft are often made of ceramics and carbon laminates with higher IR emissivity than convective radiators made of simple metals.
    From the article you're commenting on:
    > The chips can operate for about 15 minutes in space before needing to be shut down so they can cool off, said Travis Beals, Google’s senior director of product management for Project Suncatcher.
    The Thermal Control section on NASA's Small Spacecraft documentation center is quite an interesting read for this subject: <a href="https://www.nasa.gov/smallsat-institute/sst-soa/thermal-control/" rel="nofollow">https://www.nasa.gov/smallsat-institute/sst-soa/thermal-cont...
    ML Infrastructure comes with some pros (larger emissive footprint) and cons (exponentially larger TDP) compared to the concerns there, but if you aren't familiar with the challenges of heat dissipation in space, please give it a read.
    There's also a pretty interesting pop-sci article on cooling the Webb telescope, since it needs to be especially cold for its purpose. Not directly related, but may give insight into both challenges and solutions as well as well. <a href="https://science.nasa.gov/mission/webb/science-overview/science-explainers/how-does-webb-stay-cold/" rel="nofollow">https://science.nasa.gov/mission/webb/science-overview/scien...
    GMoromisato · 1790277636 · focus · HN ↗
    Emissivity is one factor, but it is dwarfed by the T^4 term. Sure, maybe if you use exotic materials you can get from 0.9 to 0.95 emissivity, but why bother? Just run the radiators a little hotter.
    The equation is:
    A ~ (1000 P) / (2 e k T^4)
    Where
    A is the radiator area in square meters P is the power in kilowatts e is emissivity (usually 0.9) k is the constant 5.67e-8
    P and T are the dominating factors. Don't worry about emissivity.
    devmor · 1790278519 · focus · HN ↗
    Emissivity is an important factor here because as I said, and as the sources I linked for you to reference clearly stated convective radiation is not taking place in space.
    Both Google and NASA are worried about this for a reason, if you think they are wrong, you should offer your assistance to them, rather than debating me.
    GMoromisato · 1790279092 · focus · HN ↗
    My point is you don't need fancy/expensive materials for your radiator. Anodized aluminum is at 0.8. With inexpensive coatings you can get to 0.9.
    If your argument against space datacenters is "radiator materials are too expensive" then I just think that's not a very good argument.
    devmor · 1790290906 · focus · HN ↗
    Oh, sure yeah I agree with that. I was just making a point about the “big hunk of metal” comment and the fact that emissivity is important because the expense of radiator materials aren’t the problem - the surface area (and mass) of the radiator is.
    GMoromisato · 1790293966 · focus · HN ↗
    And I agree with you on that. "Big hunk of metal" was too much of an exaggeration--SpaceX's design has liquid cooling, so I assume they have some channels or tubs running through the radiator, plus pumps, etc.

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