Cooling in space is hard but not impossible - while current (IMHO stupid without advanced in space infra) space data center projects work with a couple MW, many advanced space propulsion concepts might have to reject hundreds of MW if not a couple GW.

For that you might need more advanced stuff like liquid droplet radiators (https://en.wikipedia.org/wiki/Liquid_droplet_radiator), heat sinks & pulsed operation. Still, it should be eventually doable.

As for space data centers - I think the main issue is the complete lack of in space infrastructure for resource mining, processing and manufacturing & maintenance. It is kinda like building your first practical steam locomotive & the deciding to build directly an airliner. No suitable materils, experience, work force, material sources, etc.

We eventually went from locomotives to airliner, in an incremental manner & expanding the supporting infrastructure to support the ever more ambitious projects.

No point in running them at room temperature. GPUs, etc. run fine at 95 C. If you run your cooling loop at 70 C instead, you get 70% more cooling compared to 27 C.

At any rate, 1 MW for a single satellite is fine. Just launch several thousand of those and you get to real numbers.

Also, there's no need to talk about "magic" radiators. You orient them so they're at a knife edge to both the Sun and Earth. This is not difficult (the Moon is irrelevant).

> Now, input power. Sunlight in orbit ~1,360 W/m², assume ~22% cell efficiency, we got 300 W/m². So each 1 MW compute, 3,300 m² of solar panel and minimum 1,200–1,500 m² of radiator.

We need > 2x more solar panels than we need radiators. Doesn't this imply radiation isn't really the limiting factor here?

Radiating 1MW at 500K (227C) with a 0.4MW heat pump takes about 200 m^2 flat sheet surface. Inputs - solar+nuclear for double fun. So - quite feasible.

Glad you are on the case before these companies foolishly waste their money sending datacenters to space.

Getting this all up into orbit it obviously the hard part, but if you're already building so much solar capacity the cooling actually doesn't seem unreasonable?

Surface area is a materials problem? Folded microstructure, atomic-scale textured surface or some other science-fiction solution could have square kilometers of surface area in a shoebox.

Great read, thanks for sharing. I am interested in reading some more about the other unsolvable problems that exist in this space, do you have any recommendations that you wouldn't mind pointing me at? It would be greatly appreciated, and thank you :)

Is it possible for one side of panel to be used for solar power and other side for radiating heat?

Wouldn't this be solved like similar problems on earth by making small structures with large surface areas?

Don’t you get 4 faces to radiate away, assuming a long rectangular tube.

It would be a shame if a rock came out of nowhere and hit that many square kilometers stucture

Luckily, there are almost no rock in space.

there are two arguments for it.

one is marketing.

the other is that you could make tiny datacenters and flood the sky with them. in effect, not datacenters at all, but some kind of dataswarm coordinating at literal lightspeed via lasers.

they'd still be wildly expensive to deploy, and probably litter the orbit zone with fast-moving debris.

> 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.

Is it at least a 1:1 usage / cooling cycle?

you need a gradient from hot to cold to generate electricity. vacuum is a poor thermal conductor, so your cold part will become hot and then no more gradient.

(I guess you could try to capture the radiative photons via the photoelectric effect?? but I don't think it works.)

It's a scam when Elon does it.

It's Golden Dome when Google does it.

I guess it's something along the same line when Jeff Bezos does it. He does indeed plan it.

What is China's motive? why do they also need to pretend they want space data centers? [0], [1]

How about Europe's? [2]

[0] - https://www.tomshardware.com/tech-industry/space/china-puts-...

[1] - https://www.reuters.com/science/china-vows-develop-space-tou...

[2] - https://ascend-horizon.eu/data-centres-in-space/

This is the most interesting perspective I've heard on this topic, which otherwise always converges on the same political dismissals or heat dissipation arguments (the latter are fascinating, but going in circles by now).

Sounds very probable: gives a plausible reasons for sending a lot of infra up, absolutely doesn't have to be profitable or even effective, puts the focus on AI instead of the MIC, and is in line with the kind of contracts Big Tech runs after.

To me this model explains a lot of why so many big companies seem to be investing into what every expert I've heard says goes against basic physics. The only thing missing for it to be more than an interesting idea is why China and the EU are not fighting this.

just like reusable rockets sending astronauts to the space station and internet in the sky. imagine if they delivered on those bs marketing claims?

He is free to launch his own space GPU if he is so confident it is profitable*.

I will take it as a given that the Google engineers know what they are doing, and their first version can only run for 15 minutes before it needs to shut down to cool.

*Profitability requiring that other Musk controlled companies do not pay for the service at elevated rates in a classic self dealing scheme.

That guy is baffled we're not all driving around in cybertrucks talking to mecha-hitler. Why would i care?

That is not a fake argument, but real physics. Yes, you can design out X kw can be dissipated by this much radiators, but that adds an enormous quantity of mass, more than the solar panels that feed it.

If you are trying to generate a profit, every extra kg puts you further in the red. It still costs over $1000/kg of mass to get into orbit.

> This is one of the easiest problems to solve. /../ All you need is a cheap way to launch mass to orbit.

So... not easy? I don't suppose we're at a point where you could reasonably send a large-enough radiator for a multi-gigawatt cluster into space?

> 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: 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. https://science.nasa.gov/mission/webb/science-overview/scien...

It will never be cheaper to put compute into orbit. And costs for AI are dropping like a rock here on Earth.

and yet notice how the cooling video / section was the only one they didn't have a solution for... just saying "radiator" doesn't make sense - the radiator heats up too. it's how you get rid of the heat, not where you put it.

Is Kessler syndrome priced into cost? Or is that just like, someone else's problem?