Datacenters in space aren't going to work
(taranis.ie)495 points by mindracer 4 days ago
495 points by mindracer 4 days ago
I tried Google and it pointed me to a ycombinator video about Starcloud https://youtu.be/hKw6cRKcqzY They launched a satellite with one H100 in on Nov 2nd.
>I mean, when you tell people that within 10 years it could be the case that most new data centers are being built in space, that sounds wacky to a lot of people, but not to YC. (8:00)
You can radiate the excess energy away on the non-sun facing part. In theory.
There are even commercially available prototypes of that vacuum cooling technology, if you want to perform your own experiments with that concept: https://www.amazon.com/Thermos-Stainless-Ounce-Drink-Bottle/...
this kind of sarcasm will go over their head. People truly don't understand vacuums
I absolutely don't understand how vacuum works. So I absolutely cannot model how a Dewar flask which has 15 billion light year thickness between the inner and outer wall - a wall that is very close to absolute zero will behave.
I wonder if there should be levels of "in theory". Yes theoretically black body radiation exist and well stuff cools down to near background radiation via that. But the next level is theoretical implementation. Like actually moving around the heat from source and so on. Maybe this could be the spherical cow step...
Reminds me of the hyperloop. Well yes, things in vacuum tube go fast. Now does enough things go fast to make any sense...
>Now does enough things go fast to make any sense...
You're worried about rates when we can't even get the ball rolling on safety for human occupancy, maintenance, workability.
I swear, nothing on Earth more dangerous than someone with dollar signs in their eyes.
Heat conduction requires a medium, but radiation works perfectly fine in a vacuum. Otherwise the Sun wouldn't be able to heat up the Earth. The problem for spacecraft is that you're limited by how much IR radiation is passively emitted from your heat sinks, you can't actively expel heat any faster.
There is some medium in low Earth orbit. Not all vacuums are created equal. However, LEO vacuum is still very, very sparse compared to the air and water we use for cooling systems.
The main way that heat dissipates from space stations and satellites is through thermal radiation: https://en.wikipedia.org/wiki/Thermal_radiation.
Hot objects emit infrared light no matter the conditions. The hotter the object, the more light it throws off. By radiating this light away, thermal energy is necessarily consumed and transformed into light. It's kind of wild actually
No, you can't. You need to radiate away all the heat being received from the sun facing half, AND excess heat from the compute. Even in theory, the non-sun-facing part doesn't give you any benefit. It's already part of the system that accounted for the temperature of the sun-facing side.
"just as well"?
I man you totally can radiate excess heat energy on earth, but your comment implies that the parents idea of radiating off excess "energy", specifically HEAT energy in space is possible, which it isn't.
You can radiate excess energy for sure, but you'd first have to convert it away from heat energy into light or radio waves or similar.
I don't think we even have that tech at this point in time, and neither do we have any concepts how this could be done in theory.
Passively yeah. Can't imagine it's anywhere near as fast as evap or chillers
There's no air and negligible thermal medium to convect heat away. The only way heat leaves is through convection from the extremely sparse atmosphere in low Earth orbit (less than a single atom per cubic millimeter) and through thermal radiation. Both of which are much, much slower than convection with water or air.
Space stations need enormous radiator panels to dissipate the heat from the onboard computers and the body heat of a few humans. Cooling an entire data center would require utterly colossal radiator panels.
I'mma guess that AI mixed up "datacenter" with "Dyson" to get nonsensical returns involving both vacuums AND space!
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If you would kindly consult your Human HR Universal Handbook (2025 Edition) and navigate to section 226.8.2F, you’ll be gently reminded that it’s the responsibility of any and all employees to train their replacements.
Interestingly, this comment gets a lot of downvotes.
If you don't want to help improve the world, then how are you expecting things to become better?
I understand that people don't like it that this will give Google an advantage. But what is the proper alternative? We have no non-profit organizations who could muster the money to build these systems. I suppose those who are critical of large companies would also be critical of governments building these systems.
So is what you (downvoters) propose here to just complain and do nothing about it? I'd be curious to hear what alternatives you propose.
One thing I haven't seen talked about at all: how quickly would space heat up?
I presume Earth's gravity largely keeps the exosphere it has around it. With some modest fractional % lost year by year. There is a colossal vast volume out there! But given that there's so little matter up in space, what if any temperature rise would we expect from say a constant 1TW of heat being added?
The sun’s radiation hitting earth is 44,000 terawatts. I think we’re fine with an “extra” terawatt. (It’s not even extra, because it would be derived from the sun’s existing energy.)
https://www.nasa.gov/wp-content/uploads/2015/03/135642main_b...
At sea-level there can be 1.225 kg/m^3 of particles. There's a lot of matter to absorb heat.
In the exosphere we have 1e-13 kg/m^3 of particles.
My point is that the exosphere while huge has an incredibly tiny thermal battery. I'm not convinced that, were we able to dump heat into it, that it really would be insignificant heating over time.
And there's little way for the articles here to cool down. There's no matter to transfer their energy to.
I guess the thing is, it doesn't matter. It seems like the exosphere is actually already >500 degrees: that after you leave the 80km menopause temperatures soar quickly, in what scant air is left. I was still using a model of thermal transfer. But the only cooling possible is passive radiative cooling, is to glow your energy away. Some of this will find other exospheric particles to hit & excite more, but they're already incredibly energetic up there, and there's just not many particles at all, so perhaps a lot of that radiation might escape the exosphere without collision. Again my mistake: thermal transfer is simply not that relevant (aside some shielding against these particles in vulnerable spots), it's all passive radiation being used to cool.
It would still be interesting to me to have some guestimates for what the current energy balance of the exosphere is. What is heating it, how much, and where/how-much is it able to dissipate its energy?
Not a space geek but would have guessed at all these things. Feels like common sense. How is anything easier in space? None of it makes sense to me either.
The only thing I could think of is maybe 24h sunlight if far enough away from earth.
Maybe is anothet bubble to grab investor money. A bored ape larping as science.
One mistake that the article seems to make is to assume that the data center is in one huge satellite.
I think a better model would be a fleet of rack or server level satellites. That significantly reduces the heat and cooling requirements and improves redundancy since losing a single satellite sure to radiation would be less significant. Further, due to economies of scale these satellites could be produced in mass, similar to the starlink satellites of today.
One issue is that these satellites would be to be connected via high bandwidth free space optical links instead of Ethernet, requiring precise formations, but that is currently being tested by multiple companies.
That being said, I don't see this ever being cheaper than terrestrial data centers. I just don't think the idea is as stupid as the article implies - it just requires doing things differently than NASA has done in the past.
Eager space did a pretty thorough hypothetical cost breakdown of orbital data centers that I recommend. https://www.youtube.com/watch?v=JAcR7kqOb3o
Except you don’t build a data center, you add a GPU to an individual starlink node. If you can do that a couple hundred or thousand times you’ve got a lot of compute in space. The next question is how would you redesign compute around your distributed power and cooling profiles? The article doesn’t talk about the actual engineering challenges. (Such as scaling down the radiative cooling design, matching compute node to the maximum feasible power profile, etc)
I’m not arguing it’ll be easy or will ultimately work, but articles like this are unhelpful because they don’t address the fundamental insight being proposed.
OpenAI has over 1 million GPU.
Starlink satellites would be pointless for doing computation because they are spread across the Earth resulting in horrible latency. AI companies spend lots of money on super fast connects within a datacenter.
Starlink with GPU might have some advantage for running edge GPU. But most Starlink customers are close to ground station and it makes a lot more sense to have GPUs there. It is a lot easier to manage them than launching new satellites which could take years.
This idea is so spectacularly stupid that it's a shame such a smart guy needed to spend even 5 minutes refuting it.
You probably wanna launch these https://www.youtube.com/watch?v=mfk0vTe46ds
> roughly 200 GPUs. This sounds like a lot, but lets keep some perspective: OpenAI's upcoming Norway datacenter is intending to house 100,000 GPUs, probably each more power hungry than the H200
So.. 500 reusable rocket travels in space to match an on-ground datacenter? If this is the central argument then it doesn't hold.
Don't get me wrong. I too think whole idea is so outlandish it's likely to never happen, but mostly because the complexity of the whole project is too high.
Well we need like successful technological disruptions like in 7 dimensions before this can be scale and ROI positive.
So what?
Of course it’s stupid and it’s never going to work. The same is true for Carbon Capture and Storage, blue hydrogen, etc. It’s nonsense from the start, but it didn’t stop governments around the world to spend billions on it.
It works like this: companies spend a few millions on PR to market a sci-fi project that’s barely plausible. Governments who really want to preserve the status quo but are pressured to “do something” can just announce that they’re sinking billions in it and voila! They’re green, they’re going to save the world.
It’s just a scam to get public money really.
None of these problems seem intractable, just really hard and probably not being solved soon, but one has to start somewhere... so at least the billionaires will fund some scientists and engineers who will do that work?
Shhh, I'm begging people, if brain-dead VCs want to waste their money on things that are obviously farcical (and not actively destructive), please let them and stop doing their due diligence for them. The alternative is that they turn their impossible amounts of capital towards societally-destructive acts like buying up all the real estate in the world and turning us back into land-slaves.
The advantage of space is that you have infinite scale. Maybe data centers in space do not work at low scale but you have to think of them at much larger scale.
Elon Musk considered data centers in space simply for the fact that more solar power is available in space than Earth
Regardless of how terrible an idea it is, I wouldn't mind some billionaires funding R&D that advances the state of the art in thermal management in space.
Perhaps Elmo can move his toxic, illegal, cancer inducing, gas generators there, instead of doing it in Memphis. https://tennesseelookout.com/2025/07/07/a-billionaire-an-ai-...
It probably shouldn't be so hard to find military application for more compute in space. Especially give the global surveillance and communication networks like starlink and intelligence sats.
What better way to cover up such space compute capabilities than the AI madness.
Even if they are a terrible idea, we should try it out. Specially if paid with private equity. Imagine the things we will learn, the STEM jobs this will create[^1], and the fact we will bootstrap other industries.
[^1]: Provided that ChatGPT doesn't hoard all of them :-)
Another great write-up on datacenters in space that goes a bit deeper in cost calculations: https://angadh.com/space-data-centers-1
“Terrible, horrible, no good” is the new “considered harmful.”
Apparently the book whose title the phrase comes from [1] was published in 1972, four years after Dijkstra published "Considered Harmful".
[1] https://en.wikipedia.org/wiki/Alexander_and_the_Terrible,_Ho...
Additionally, their distributions were different. People who read Dijkstra circa 1968 started using the phrase in their own publications within a decade, whereas people who read Viorst (or had it read to them) in 1972 and following years had at least a few decades of further delay before publishing anything using the corresponding phrase.
I agree with most of this post and think the problems are harder than the proponents are making them seem.
But, 1) literally the smartest people and AI in the world will be working on this and 2) man I want to see us get to a type 2 civilisation bad.
The layout of this blog post is also very interesting, it presents a bunch of very hard items to solve and funny enough the last has been solved recently with starlink. So we can approach this problem, it requires great engineering but it’s possible. Maybe it’s as complicated as CERNs LHC but we have one of those.
Next up then is the strong why? When you’re in space, if you set the cost of electricity to zero, the equation gets massively skewed.
Thermal is the biggest challenge but if you have unlimited electricity, lots of stuff becomes possible. Fluorinert cooling, piezoelectric pumps and dual/multi stage cooling loops with step ups. We can put liquid cooling with piezos on phones now, so that technology is moving in the right direction.
For a thought experiment, if launch costs were $0/kg, would this be possible? If the answers yes, then at some point above $0/kg it becomes uneconomical, the challenge is then to beat that number.
I don't agree with the logic that "something is hard/can't be done right now" is equivalent to "this is a terrible idea and won't work."
There are dozens of companies solving each problem outlined here; if we never attempt the 'hard' thing we will never progress. The author could have easily taken a tone of 'these are all the things that are hard that we will need to solve first' but actively chose to take the 'catastrophically bad idea' angle.
From a more positive angle, I'm a big fan of Northwood Space and they're tackling the 'Communications' problem outlined in this article pretty well.
It's not that it's hard, it's that it's stupid - it's based on a misunderstanding of the physics involved which completely negates any of the benefits.
It's the opposite of engineering, where you understand a problem space and then try to determine the optimal solution given the constraints. This starts with an assumption that the solution is correct, and then tries to engineer fixes to gaps in the solution, without ever reevaluating the solution choice.
From: https://engine.xyz/resident-companies/northwood-space
> Unlike traditional parabolic dish antennas, our phased array antenna can connect with multiple satellites simultaneously.
if that's how they plan to reach more than 1Gbps, then that's not 100Gbps per satellite, that's 100 for a collection of satellites.
Starlink is about 100Mbps. That's 1000x times less than 100Gbps
What reason is there to build datacenters in space, though? Literally, what limitation do we face in building datacenters on Earth would building them in space improve?
The surface area of the earth is the limit (which only gets sunlight half the time) and only gets 1 billionth the energy emitted by the sun vs relatively unlimited surface area of solar panels in space
There are things which are difficult and have unsolved problems, and there are things that just fundamentally make no sense.
Nobody is proposing data centers at the South Pole. This isn’t because it’s difficult. It is difficult, but that’s not the reason it’s not being looked at. Nobody’s doing it because it’s pointless. It’s a massive hassle for very little gain. It’s never going to be worth the cost no matter what problems get solved.
Data centers in space are like that. It’s not that it’s difficult. It’s that the downsides are fundamentally much worse than the advantages, because the advantages aren’t very significant. Ok, you get somewhat more consistent solar power and you can reach a wider ground area by radio or laser. And in exchange for that, you get to deal with cooling in a near perfect insulator, a significantly increased radiation environment, and difficult-to-impossible maintenance. Those challenges can be overcome, sure, but why?
This whole thing makes no sense. Maybe there’s something we just aren’t seeing, or maybe this is what happens when people are able to accumulate far too much money and nobody is willing to tell them they’re being stupid.
That's not the argument though. The argument is "it can be done, the methods to do it are known, but the claims about space being an optimal location to locate our AI datacenters are false and the tradeoffs and unit economics of doing it makes no sense compared with building a data centre on earth somewhere with power and water, preferably not too hot.
But for a more nuanced and optimistic take, this one is good and highlights all the same issues and more https://www.peraspera.us/realities-of-space-based-compute/
(TLDR: the actual use cases for datacentres in space rely on the exact opposite assumption from visions of space clouds for LLMs: most of space is far away and has data transmission latency and throughput issues so you want to do a certain amount of processing for your space data collection and infrastructure and autonomous systems on the edge)
Datacenters in space may not work now but in the future when we get the robots a bit better who knows? From the Google blog:
>The Sun is the ultimate energy source in our solar system, emitting more power than 100 trillion times humanity’s total electricity production. In the right orbit, a solar panel can be up to 8 times more productive than on earth, and produce power nearly continuously, reducing the need for batteries. In the future, space may be the best place to scale AI compute.
"[..] deploying a solar array with photovoltaic cells – something essentially equivalent to what I have on the roof of my house here in Ireland, just in space. It works, but it isn't somehow magically better than installing solar panels on the ground – you don't lose that much power through the atmosphere"
As an armchair layman, this claim intuitively doesn't feel very correct.
Of course AI is far from a trustworthy source, but just using it here to get a rough idea of what it thinks about the issue:
"Ground sites average only a few kWh/m²/day compared to ~32.7 kWh/m²/day of continuous, top-of-atmosphere sunlight." .. "continuous exposure (depending on orbit), no weather, and the ability to use high-efficiency cells — all make space solar far denser in delivered energy per m² of panel."
I'm not impressed by these arguments.
(1) Solar panels can be made much lighter in space. On Earth, panels have to withstand wind and gravity loads, flying debris, and precipitation including hail. The PV material itself doesn't have to be thick: thin film CdTe cells can be ~1 micron thick (the absorption length of the relevant photons in CdTe is something like 0.1 microns.) There has to be a protective layer to prevent solar wind ions from degrading the cells but this doesn't have to be very thick. It's not like shielding against high energy particles.
(2) Heat dissipation can be addressed by refrigeration. Yes, this takes energy, and yes that extra energy also has to be radiated. But the area of the radiator goes down as the fourth power of its absolute temperature. If you radiate 2x as much heat but at 2x the absolute temperature, the area of the radiator declines by a factor of 8. Even with inefficiencies one should be able to come out ahead by pumping the waste heat to higher temperature before radiating it.
(3) Ionizing radiation is dealt with by shielding. The amount of shielding per unit of capacity declines as you make your installation larger, by the square cube law. So this is really just a matter of scale. We're talking about potentially enormous amounts of capacity here so shielding shouldn't be a problem at scale.
The one thing that space has going for itself is space. You could have way bigger datacenters than on Earth and just leave them there, assuming Starship makes it cheap enough to get them there. I think it would maybe make sense if 2 things: - We are sure we will need a lot of gpus for the next 30-40 years. - We can make the solar panels + cooling + GPUs have a great life expectancy, so that we can just leave them up there and accumulate them.
Latency wise it seems okay for llm training to put them higher than Starlink to make them last longer and avoid decelerating because of the atmosphere. And for inference, well, if the infra can be amortized over decades than it might make the inference price cheap enough to endure additional latencies.
Concerning communication, SpaceX I think already has inter-starlinks laser comms, at least a prototype.
You can't just "leave them there" though. They orbit at high speed, which effectively means they actually take up vastly more space, with other objects orbiting at high speed intersecting those orbits. The orbits that are most useful are relatively narrow bands shared with a lot of other satellites and a fair amount of debris, and orbits tend to decay over time (which is a problem if you're in low earth orbit because they'll decay all the way into the atmosphere, and a problem if you're in geostationary orbit because you'll lose the advantage of stationary bit for maintaining comms links). This is a solvable problem with propulsion, but that entails bringing the propellant with you and end-of-life (or an expensive refuelling operation) when it runs out. The cost of maintaining real estate space is vastly more than out right owning land.
Similarly, making stuff have a great life expectancy is much more expensive than having it optimized for cost and operational requirements instead but stored somewhere you can replace individual components as and when they fail, and it's also much easier to maximise life expectancy somewhere bombarded by considerably less radiation.
There is lots and lots and lots of space on Earth where hardly anyone is living. Cheap rural areas can support extremely large datacenters, limited only by availability of utilities and workers.
Yet a colossal number of servers on satellites would require the same energy-production facilities to be shipped into orbit (and to receive regular maintainence in orbit whenever they fail), which requires loads of land for launch facilities as well as processing for fuel and other consumable resources. Solar might be somewhat more efficient, but not nearly so much so as to make up for the added difficulty in cooling. One could maybe postulate asteroid mining and space manufacturing to reduce the total delta-V requirement per satellite-year, but missions to asteroids have fuel requirements of their own.
If anything, I'd expect large-scale Mars datacenters before large-scale space datacenters, if we can find viable resources there.
Launching a datacenter like that carries an absurd cost even with Starship type launchers. Unless TSMC moves its production to LEO it's a joke of a proposal.
Underwater [0] is the obvious choice for both space and cooling. Seal the thing and chuck it next to an internet backbone cable.
> More than half the world’s population lives within 120 miles of the coast. By putting datacenters underwater near coastal cities, data would have a short distance to travel
> Among the components crated up and sent to Redmond are a handful of failed servers and related cables. The researchers think this hardware will help them understand why the servers in the underwater datacenter are eight times more reliable than those on land.
[0] https://news.microsoft.com/source/features/sustainability/pr...
The problem is a lot of people like the underwater idea and I’m worried we’re heading towards something like literally boiling the ocean as they say.
No worries, the oceans are cooked already.
Space is not much of an issue for datacenters. For one thing, compute density is growing; it's not uncommon for a datacenter to be capacity limited by power and/or cooling before space becomes an issue; especially for older datacenters.
There are plenty of data centers in urban centers; most major internet exchanges have their core in a skyscraper in a significant downtown, and there will almost always be several floors of colospace surrounding that, and typically in neighboring buildings as well. But when that is too expensive, it's almost always the case that there are satellite DCs in the surrounding suburbs. Running fiber out to the warehouse district isn't too expensive, especially compared to putting things in orbit; and terrestrial power delivery has got to be a lot less expensive and more reliable too.
According to a quick search, StarLink has one 100g space laser on equipped satellites; that's peanuts for terrestrial equipment.
We have tons of space on earth. Cooling in space would be so expensive.
In exchange for what benefit? There is literally no benefit to having a datacenter in space.
Starship is on a fast track to failure. It is not a cheaper way to get to orbit and will never get there at the current pace. And even if it were, it would not make getting to orbit so cheap that it would somehow make it economically viable to put a datacenter there.
You still have to build the GPUs, etc for the datacenter whether it’s on Earth or in orbit. But to put it in space you also need massive new cooling solution, radiation shielding, orbital boosting, data transmission bandwidth, and you have to launch all of that.
And then, there are zero benefits to putting a datacenter in space over building it on Earth. So why would you want to add all that extra expense?
It will make getting to orbit cheaper, significantly so, but I can't see it being rapidly reusable. Rapidly refurbishable perhaps if Starship were modular and the heat shield could be quickly swapped out on site where necessary. But being able to top off the methalox and fly again? That's a pipe dream. Orbital spaceflight isn't like air travel in any sense.
I asked Google for more information about AI datacenter in space. This was the first sentence, 'AI data centers are being developed in space to handle the massive energy demands of AI, using solar power and the vacuum of space for cooling.'
> After laughing at "the vacuum of space for cooling" I closed the page because there was nothing serious there. Basic high school physics student would be laughing at that sentence.