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Comment by sobellian | Hacker News Reader

Commercial GPUs already fail a lot and that's before you put them in LEO. Starlink is doing something that can't be accomplished anywhere else than space. If you could somehow have ground stations that can give wireless internet to every corner of the Earth you would much rather do that. Again, this is all physically possible, but the question is whether it's wise, whether it's saving money or if it's just a giant Rube Goldberg machine. If you assume Starlink satellite $/W then even if launch is zero, it costs twice as much as terrestrial using assumptions charitable to orbital.

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Fair point about the failure rates. I wonder what causes that, given that there are no moving parts... if it's temperature fluctuations, maybe you could just run the GPU at 100% all the time to avoid that, given that the marginal cost of power for a satellite already in space is $0?

> If you assume Starlink satellite $/W

Why would you assume that, given that high power output is not a design goal of Starlink?

The calculator I've cited elsewhere uses https://chatgpt.com/share/69391474-4b24-8005-bb93-ebd4340c65.... The various starlink versions have approximately the same cost per watt across very different power levels. Much of the cost is going to be ~proportional to power - solar panels, heat rejection, power electronics, etc. Listen, if they could make it cheaper to deliver the same amount of power they would. Starlink is approximately all of SpaceX's business.

ETA: power is absolutely important for Starlink. SNR is very important for shannon capacity and satellite systems are often limited in this respect.

So ChatGPT decided to assume a constant $800/kg to estimate cost, and you're using that as evidence that cost/W doesn't decrease with scale?

Anyway, my point is that Starlink is not primarily designed to harvest as much solar power as possible the way data center sats are. I'm sure they're not making it inefficient on purpose, but what you're suggesting is like using the cost/W of a solar powered traffic camera to estimate the cost/W of a solar farm. Yes, they both use solar power, but they have entirely different design goals.

It's reasonable to 0th order to assume a ball of heat management and phased array antennae has a roughly constant cost per kg, yes. And as I said starlink absolutely wants to use as much power as they can, as communications from space are heavily limited by power.

FWIW, SpaceX is estimating their AI sats will have over double the W/kg of what that ChatGPT summary is estimating for Starlink. https://www.spacex.com/spacexai/starmind Cost/kg is not disclosed, but I think it would be a mistake to assume there were no similar improvements there.

Okay so even assuming all of SpaceX's numbers, which is extremely optimistic, even if we're an angel's advocate and assume that they spend all this money on engineering and optimize their launch costs and their satellite costs and they don't hit any hiccups, and DCs on Earth stay pretty much the same and don't get any added efficiencies. Even then over every time period orbital is still more expensive. And it gets particularly punishing the longer you extend the analysis period as the satellites need to get replaced while the DCs don't spontaneously combust all their infra.

I don't think those numbers are optimistic, I suspect they've already designed the sat in CAD and that's what the calculation spat out; it's probably quite accurate. The physics of this sort of thing are quite well known and SpaceX already has experience with the type of satellite that will be needed. There's no need for them to rely on napkin math.

Cost is a different matter of course, but it seems incongruous to me that after being confronted with the fact that your power density assumptions were off by a factor of 2x you would continue to insist ChatGPT's weird assumptions about manufacturing costs scaling linearly with mass are accurate. As was already pointed out upthread, even if all the calculator's other assumptions are correct they can turn a profit if they get the per satellite cost (excluding the cost of the GPUs) below $2 million. I think the only big question mark here is launch cost.

Upthread comment and therefore the premise of your $8/W target is wrong. As I explained, I plugged in all the announced engineering parameters for Starmind, $8/W, and $76/kg launch. It ties terrestrial over a 5yr period (the slider default) but gets crushed over a 10yr period. Naturally a longer time window is prudent absent some world-ending calamity in 5 years that renders the need for compute irrelevant. And even the 5yr tie is very sensitive to these parameters and requires everything to go right.

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