> This is a question that analysts don't even ask

On the contrary, data centers continue to pop up deploying thousands of GPUs specifically because the numbers work out.

The H100 launched at $30k GPU and rented for $2.50/hr. It's been 3 years since launch, the rent price is still around $2.50.

During these 3 years, it has brought in $65k in revenue.

We have radiators on the ISS. Even if you kept the terrible performance of those ancient radiator designs (regularly exposed to sunlight, simplistic ammonia coolant, low temperature) you could just make them bigger and radiate the needed energy. Yes it would require a bit of engineering but to call it an "unsolved problem" is just exaggerating.

That is a fun thought experiment, as we wouldn't want to manufacture too far away from earth we may still be within the earth's atmosphere. I wonder what effect dumping greenhouse gases into the very upper levels of the atmosphere would have in comparison to doing it lower down. My assumption is it would eventually sink to a lower density layer, having more or less the same impact.

Overview energy has done interesting work in this area.

It's always better to generate electricity on the ground than attempt to beam it to the ground from space. The efficiency loss of beamed power is huge.

Why would you transfer the energy to earth? The energy powers ai compute = $

Perhaps parent was being sarcastic.

It's worth noting that the EACTS can at maximum dissipate 70kW of waste heat. And EEACTS (the original heat exchange system) can only dissipate another 14kW.

That is together less than a single AI inference rack.

And to achieve that the EACTS needs 6 radiator ORUs each spanning 23 meters by 11 meters and with a mass of 1100 kg. So that's 1500 square meters and 6 and a half metric tons before you factor in any of the actual refrigerant, pumps, support beams, valve assemblies, rotary joints, or cold side heat exchangers all of which will probably together double the mass you need to put in orbit.

There is no situation where that makes sense.

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Manufacturing in space makes sense (all kinds of techniques are theoretically easier in zero G and hard vacuum).

Mining asteroids, etc makes sense.

Datacenters in space for people on earth? That's just stupid.

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.

The distinction is that what they are doing for Webb is trying to dissipate small amounts of heat that would warm up sensors past cryogenic temperatures.

Like on the order of tens or hundreds of watts but -100C.

Dissipating heat for an AI datacenter is a different game. A single AI inference or training rack is going to be putting out somewhere around 100kW of waste heat. Temps don't have to be cryogenic but it's the difference between chiselling a marble or jade statue and excavating a quarry.

That's a solution for minuscule amounts of heat that nevertheless disturb extremely sensitive scientific experiments. Using gold, no less. This does not scale to a crapton of GPU waste heat.

Anything is possible here, it's just there's no goddamn reason to do any of this. You're giving up the easiest means of cooling for no benefit and you add other big downsides.

It's scifi nonsense for no purpose other than to sound cool.

Seems a bit of both. But no disparagement to your floor mopping (as I once was a dishwasher in a commercial kitchen myself), but there's a big gap between cleaning a floor, or a dish, and creating frontier models and spaceships.

That said: I think solar is niche, and a moon-shot for how they want it. Nuclear is the future of reliable energy for human civilization.

I think the K-scale is the wrong metric. I don't think we should be trying to take all the sun's energy as a goal (don't blot out the sun! don't hide it in a bushel!), or as a civilizational utiltiy - I'm sure better power supplies will come along.

I disagree, I think the idea of a cabal of reactionary comrades inside SpaceX is activist fantasy. I think SpaceX only does what it does with full committment of its people: mind, body, spirit.

I'm not aware of this - What's that?

He's bailing out one of his failing ventures with one of his so far successful ones. The BS napkin math isn't the reason he's doing it. It's the excuse for doing it.

Can you provide a link for that quote, because that quote is absolute stupidity.

On the other hand, Tesla vehicles have similar hardware built into them, and don't require such hands-on intervention. (And that's the hardware that will be going up.)

It's not like satellites need anything like computer chips, which are finicky things to build that require parts with a sole supplier on the entire planet.

>From lunar regolith you would extract: oxygen, iron, aluminum, titanium, silicon, calcium, and magnesium.

Do we actually know how to do that?

>From the poles

From the poles! So the proposal includes building a planetary-scale railway network on bumpy lunar terrain.

>The moon can supply mass, oxygen, fuel, and structure.

None of those are things we are hurting for down here, though.

Power would almost certainly mostly come from solar panels. The SpaceX-xAI press release mentions using mass drivers which are electrically powered. Could make Hydrogen-Oxygen rocket fuel but not needed in Moon's lower gravity/thin atmosphere.

> The real constraint is not materials

It's solvents, lubricants, cooling, and all the other boring industrial components and feedstocks that people seem to forget exist. Just because raw materials exist in lunar regolith doesn't mean much if you can't actually smelt and refine it into useful forms.

You know how people sometimes dismiss PV by saying "what happens at night or in cloudy weather?"?

Well, what happens over the course of a year of night and clouds is that 1 TW-peak becomes an average of about 110 to 160 GW.

We're making ~1 TW-peak per year of PV right now.

The 1TW is the rated peak power output. It's essentially the same in space. The thing that changes is the average fraction of this sustained over time (due to day/night/seasons/atmosphere, or the lack of all of the above).

It's still the same 1TW theoretical peak in space, it's just that you can actually use close to that full capacity all the time, whereas on earth you'd need to over-provision substantially and add storage, so 1TW of panels can only drive perhaps a few hundred GW of average load.

Funny, I would have included transportation as part of the installation cost. You didn't mention that one.

Yeah, soft costs like permitting and inspections are supposedly the main reason US residential solar costs $3/watt while Australian residential solar costs $1/watt. It was definitely the worst and least efficient part of our solar install, everything else was pretty straightforward. Also, running a pretty sizable array at our house, the seasonal variation is huge, and seasonal battery storage isn’t really a thing.

Besides making PV much more consistent, the main thing this seems to avoid is just the red tape around developing at huge scale, and basically being totally sovereign, which seems like it might be more important as tensions around this stuff ramp up. There’s clearly a backlash brewing against terrestrial data centers driving up utility bills, at least on the East Coast of the US.

The more I think about it, the more this seems like maybe not a terrible idea.

No maintenance either

We have so much excess land with no real use for it that our government actually pays farmers to grow corn on it to burn in cars.

Availability of land for solar production isn't remotely a real problem in the near term.

Realizing the impracticality of it (and that such approaches often collapse under the infeasibility of it) ... wouldn't it be better to... say... cover the Sahara in solar panels instead? That's gotta be cheaper than shipping them into space.

https://inhabitat.com/worlds-largest-solar-project-sahara-de...

https://www.theguardian.com/business/2009/nov/01/solar-power...

(and a retrospective from 2023 - https://www.ecomena.org/desertec/ )

the demand is pretty much fake and AI isn't actually making money, just gobbling investors money

Solar can always just go on the roof...

I think this is all ridiculous, to be clear, but re: this problem couldn't the radiators in theory be oriented so that they vent in opposite directions and cancel out any thrust that would be generated?

For one or a few-off expensive satellites that are intended to last 10-20 years, then yes. But in this case the satellites will be more disposable and the game plan is to launch tons of them at the lowest cost per satellite and let the sheer numbers take care of reliability concerns.

It is similar to the biological tradeoff of having a few offspring and investing heavily in their safety and growth vs having thousands off offspring and investing nothing in their safety and growth.

Sure but like, just use even more solar panels? You can probably buy a lot of them for the cost of a satellite.

And in geostationary, the planet hardly ever gets in the way. They get full sun 99.5% of the year.

even at 10% (say putting it on some northen pile of snow) it is still cheaper to put it on earth than launch it

I'm all for efficiency, but I would think a hailstorm of space junk hits a lot harder than one of ice out on the farm.

Except it doesn't melt like regular hail so when further storms come up you could end being hit by the same hail more than once :\

> And then there’s that pesky night time and those annoying seasons.

The two options there are cluttering up the dawn dusk polar orbit more or going to high earth orbit so that you stay out of the shadow of the earth... and geostationary orbits are also in rather high demand.

That's not what I'm suggesting. The post says "deep space". If you're going to try to harvest even a tiny percentage of the sun's energy, you're not doing that in Earth's orbit. The comparison is a webcam feed from Mars.

> it is possible to put 500 to 1000 TW/year of AI satellites into deep space, meaningfully ascend the Kardashev scale and harness a non-trivial percentage of the Sun’s power

Which satellites are operating from "deep space"?

you would need 200 times the number of solar cells. I don't think you appreciate the scale that 200x is, especially when China is already:

1. quite good at making solar cells

2. quite motivated to increase their energy production via solar

  >We can make ten or hundred times the number of solar cells we make right now

The limit isn't just about the current capacity or the maximum theoretical capacity, it's also about the maximum speed you can ramp.

>In an interview with Robert Wright in 2003, Dyson referred to his paper on the search for Dyson spheres as "a little joke" and commented that "you get to be famous only for the things you don't think are serious" [...]

To be fair, he later added this:

>in a later interview with students from The University of Edinburgh in 2018, he referred to the premise of the Dyson sphere as being "correct and uncontroversial".[13] In other interviews, while lamenting the naming of the object, Dyson commented that "the idea was a good one", and referred to his contribution to a paper on disassembling planets as a means of constructing one.

Sources are in: https://en.wikipedia.org/wiki/Dyson_sphere

Have you read the paper itself, not just summaries of the idea? It's obvious from the way he wrote it, dripping in sarcasm. Talking about "Malthusian principles" and "Lebensraum", while hand waving away any common sense questions about how the mass of Jupiter would even be smeared into a sphere around the sun, just saying that he can conceive of it and therefore we should spend public money looking for it. He's having a lark.

Also, he literally said it was a joke, and was miffed that he was best know for something he didn't take seriously.

https://www.youtube.com/watch?v=fLzEX1TPBFM

>> Dyson Sphere

> What do you think the limiting factor is?

You need to be able to harness enough raw material and energy to build something that can surround the sun. That does not exist in the solar system and we do not yet have the means to travel further out to collect, move, and construct such an incredibly huge structure. It seems like a fantasy.

There are only so many people who can make satellites; there are only so many things to make satellites out of; and there are only so many orbits to put them in. There are only so many reasons why a person might want a satellite. There are only so many ways of placing satellites in orbit and each requires some amount of energy, and we have access to a finite amount of energy over time.

Finally, if we limited ourselves to earth-based raw materials, we would eventually reach a point where the remaining mass of the earth would have less gravitational effect on the satellite fleet than the fleet itself, which would have deleterious effects on the satellite fleet.

Seven reasons are intuitive; I’m sure there are many others.

After a few decades, you need to start replacing all the solar panels.

And the robot army being used to do the construction and resource extraction will likely have a much shorter lifespan. So needs to be self-replicating/repairing/recycling.

The physical amount of material in the solar system is a pretty big limiting factor.

In 2026? Grift.

Tesla