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Comment by hyperbovine | Hacker News Reader

The ISS consumes roughly 90kW. That’s about *one* modern AI/ML server rack. To do that they need 1000 m^2 of radiator panels (EACTS). So that’s the math: every rack needs another square kilometer of stuff put into orbit. Doesn’t make sense to me.

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1000m2 is not a square kilometer (1 square kilometer is 1mil m2)

And what happens every time a rack (or node) fails? Does someone go out and try to fix it? Do we just "deorbit" it? How many tons per second of crap would we be burning in the upper atmosphere now? What are the consequences of that?

How do the racks (or nodes) talk to eachother? Radios? Lasers?

What about the Kessler Syndrome?

Not a rocket scientist but 100% agree this sounds like a dead end.

Communication is a well-understood problem, and SpaceX already has Starlink. They might need pretty high bandwidth, but that's not necessarily much of a problem in space. Latency could be a problem, except that AI training isn't the sort of problem where you care about latency.

I'd be curious where exactly they plan to put these datacenters... In low Earth orbit they would eventually reenter, which makes them a pollution source and you'd have no solar power half the time.

Parking them at the Earth-Sun L1 point would be better for solar power, but it would be more expensive to get stuff there.

> you'd have no solar power half the time

Polar orbit.

Seasons mess that up unless you're burning fuel to make minor plane changes every day. Otherwise you have an equinox where your plane faces the sun (equivalent to an equatorial orbit) and a solstice where your plane is parallel to the sun (the ideal case).

True. It would a tradeoff with the fuel consumed vs doubling power output.

https://en.wikipedia.org/wiki/Sun-synchronous_orbit A Sun Synchronous orbit at the Day-Night terminator solves this issue

I didn't think of that! I should have had a V8. Thanks for the info.

Huh, I didn't know that that was possible without burning fuel. Kind of wild that it only works because the Earth has an equatorial bulge and isn't an exact sphere.

Satellites can spin! You also need to deal with precession and other minor chances in the orbit, but they’re all solved problems.

> SpaceX already has Starlink. They might need pretty high bandwidth

you mean the network that has less capacity than a fibre pair per coverage area?

1000 square meters really isn't that big in space.

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