[wongarsu]

Some of the proposals are laughable, some of the example calculations are. The idea of running AI training sounds extremely challenging. But the idea of inference in space doesn't seem absurd

The power budget of a starlink v2 mini satellite is estimated at around 20kW based on the known solar panel size. That also matches what a satellite of that size would roughly dissipate without dedicated radiators, using just some heat pipes to spread the heat evenly over the satellite's surface. There is nothing fundamentally preventing you from taking the same satellite design, remove most of the comms payload and instead put 15kW of GPUs there. Or about 10 GB200 including the CPUs, networking, etc that you need along with the GPUs

Now, do the economics work out for $300k worth of compute for each satellite, in an environment where maintenance is impossible and degradation will be higher than on the ground? Probably not right now, but in a couple years they might

[beAbU]

The starlink satellites have hall effect thrusters, and presumably beefy laser and radio comms systems that will account for a lot of the energy budget. Also, they are sometimes in the earth's shadow, a naive calculation says they have 2x the solar budget they need, in order to charge up batteries for shade-time operations. There is no where near 20kw of compute in a single satellite, and thus no where near 20kw of heat to get rid of.

Furthermore, xAI's colossus supercomputer is specced at 250MW. And this seems to be a number that'll just increase over the coming years with new bigger DCs.

To match this level of performance they will have to launch what, ~15k satellites _per_ equivalent datacentre?

Regarding cooling: you can't just cover the outer surface with pipes. You cant't dissipate the heat, you need to _radiate_ it away. You need to point that surface to the deep dark cold of space. If you point it to the sun, you will heat your satellite. Think a massive "reverse solar panel" that works with infrared. You need surface area, and loads of it.

I'm not saying this is impossible. Obviously elon will prove us all wrong because he's stubborn like that. But there is no way this will ever be economically viable when competing with terrestrial based systems.

[wongarsu]

The assumption behind "spread the heat over the size of the satellite" is radiative cooling. Admittedly my numbers were a bit off, you need to make the satellite a bit bigger, or use some of your solar panels. A starlink v2 mini has 8m² of area per side, so 16m² total. To dissipate 20kW to space, at a surface temperature of 80°C and emissivity of 0.85, you need about 28m² of space. So you need to increase size a bit, or add 12m² of dedicated radiators. A bit more to deal with the real live complications (the sun exists, the earth is actually warmer than space and covers a significant portion of the sky if you are in leo, etc.).

The actual Starlink V2 Mini is has estimates for solar generation that range up to 35kW. We need a bit more, but not much more.

My numbers are a bit optimistic, but they are in the right order of magnitude. Power and cooling are very achievable in the area of putting one server on one satellite. It's the "putting one DC on one mega satellite" ideas that run into feasability issues, and for inference those aren't needed. The economics are the bigger issue, and launch costs are only moving in one direction

[beAbU]

I think you and I are coming to the same conclusion. It's totally viable to have 20kw of compute in a satellite in space. Hell, you can probably get away with 100kW or more with some sort of megasatellite.

I'm pretty sure we'll see this within the next 5 years.

But deploying a megawatt scale DC in space? And then doing that multiple times a year?? I can't see how this is the only solution to this problem. I can't see how that will be the de-facto way of deploying DCs. Not for the next 100 years or more.

[weirdmantis69]

The terrestrial based systems getting protested, blocked, and demonized everywhere? Those ones?

[beAbU]

Plop these satellites on a massive barge in the middle of the ocean with 2x the solar and battery capacity to (to account for day/night cycles) and you have exactly the same solution, only it's multiple orders of magnitude easier to "launch", service and you can actually recycle the deprecated hardware. It will also solve the cooling problem that's associated with space.

The fact that elon's colossus data centre needs to burn jet fuel on site for power tells you everything you need to know about the viability of a solar powered space based solution.

[lovich]

For everyone that’s blocked there seems to be another popping up even when the local populace voted against it.

Even then, space is still a harder place to put a satellite than any rural area on the planet.

[ashley95]

How is this not absurd? What is the benefit? Space is a harsh environment, with issues due to solar radiation etc, etc. And it's permanently 100ms away from any user.

[sulam]

Tl;dr — but it’s too heavy

You’re making some decent points here, but you’re either forgetting or ignoring the major thing that people usually neglect to mention when they want to make a case for this (crazy) idea — weight. Unless SpaceX is going to completely redesign hardware such that it is optimized entirely for its mass, it requires many (many) launches to even get a small set of racks into space. I don’t normally get up in arms about the CO2 emissions of data centers, I think there is offsetting value created by their use, but I would absolutely protest trying to put data centers in space and do my best to shut down the hundreds, if not thousands of launches it would take to achieve even a tiny fraction of an AI data center.

[jpadkins]

Have you calculated the CO2 output of Terran datacenters run on natural gas vs. space datacenters run on solar? The launch CO2 usage is one time, the datacenter energy is for the life of the equipment.

[sulam]

A Falcony Heavy probably generates 1 kiloton of CO2 per launch. Data centers on the planet are highly variable depending on their energy mix. It's true that a large a datacenter running on natural gas or coal power is significantly more in a year, but the sheer number of launches required to get that same data center into space is actually comparable, and there's no saying that this is the end of it. Oh and we should also have questions about how you safely de-orbit these things.

[vel0city]

If solar+batteries are so cheap and viable to power giant 100 megawatt datacenters in space, why not do the same on Earth instead of using natural gas generators?

[jpadkins]

Solar panels on surface get ~70% less energy than in space once you factor in atmosphere absorption, day/night, weather, etc. Solar + battery on the surface is not economically viable versus nat gas generators (excluding externalities)

[vel0city]

Sounds like the solution is to actually price the externalities of running on-site natural gas generation and suddenly we don't actually need to go to orbit.

[lovich]

What could possibly change that would make it a more economically viable option than putting it on earth. Nothing about space improves how data centers operate, and there are several new issues introduced by being in space.

And that’s before you get past the cost of actually putting the shit up there instead of just driving or shipping by rail.

It’s just more looney tunes delusion from a guy who is just talking out his ass about shit he thinks is cool, like the cyber truck was.