[mike_hearn]

But the focus on building giant monolithic datacenters comes from the practicalities of ground based construction. There are huge overheads involved with obtaining permits, grid connections, leveling land, pouring concrete foundations, building roads and increasingly often now, building a power plant on site. So it makes sense to amortize these overheads by building massive facilities, which is why they get so big.

That doesn't mean you need a gigawatt of power before achieving anything useful. For training, maybe, but not for inference which scales horizontally.

With satellites you need an orbital slot and launch time, and I honestly don't know how hard it is to get those, but space is pretty big and the only reasons for denying them would be safety. Once those are obtained done you can make satellite inferencing cubes in a factory and just keep launching them on a cadence.

I also strongly suspect, given some background reading, that radiator tech is very far from optimized. Most stuff we put into space so far just doesn't have big cooling needs, so there wasn't a market for advanced space radiator tech. If now there is, there's probably a lot of low hanging fruit (droplet radiators maybe).

[leoedin]

But why would you?

Space has some huge downsides:

* Everything is being irradiated all the time. Things need to be radiation hardened or shielded.

* Putting even 1kg into space takes vast amounts of energy. A Falcon 9 burns 260 MJ of fuel per kg into LEO. I imagine the embodied energy in the disposable rocket and liquid oxygen make the total number 2-3x that at least.

* Cooling is a nightmare. The side of the satellite in the sun is very hot, while the side facing space is incredibly cold. No fans or heat sinks - all the heat has to be conducted from the electronics and radiated into space.

* Orbit keeping requires continuous effort. You need some sort of hypergolic rocket, which has the nasty effect of coating all your stuff in horrible corrosive chemicals

* You can't fix anything. Even a tiny failure means writing off the entire system.

* Everything has to be able to operate in a vacuum. No electrolytic capacitors for you!

So I guess the question is - why bother? The only benefit I can think of is very short "days" and "nights" - so you don't need as much solar or as big a battery to power the thing. But that benefit is surely outweighed by the fact you have to blast it all into space? Why not just overbuild the solar and batteries on earth?

[elihu]

The main reason is that generating energy in space is very cheap and easy due to how ridiculously effective solar panels are.

Someone mentioned in the comments on a similar article that sun synchronous orbits are a thing. This was a new one to me. Apparently there's a trick that takes advantage of the Earth not being a perfect sphere to cause an orbit to precess at the right rate that it matches the Earth's orbit around the sun. So, you can put a satellite into a low-Earth orbit that has continuous sunlight.

https://en.wikipedia.org/wiki/Sun-synchronous_orbit

Is this worth all the cost and complexity of lobbing a bunch of data centers into orbit? I have no idea. If electricity costs are what's dominating the datacenter costs that AI companies are currently paying, then I'm willing to at least concede that it might be plausible.

If I were being asked to invest in this scheme, I would want to hear a convincing argument why just deploying more solar panels and batteries on Earth to get cheap power isn't a better solution. But since it's not my money, then if Elon is convinced that this is a great idea then he's welcome to prove that he (or more importantly, the people who work for him) have actually got this figured out.

[leoedin]

Let's assume your space solar panel is always in sun - so 8760 kWh per year from 1kWp.

In Spain, 1kWp of solar can expect to generate about 1800 kWh per year. There's a complication because seasonal difference is quite large - if we assume worst case generation (ie what happens in December), we get more like 65% of that, or 1170 kWh per year.

That means we need to overbuild our solar generation by about 7.5x to get the same amount of generation per year. Or 7.5kWp.

We then need some storage, because that generation shuts off at night. In December in Madrid the shortest day is about 9 hours, so we need 15 hours of storage. Assuming a 1kW load, that means 15kWh.

European wholesale solar panels are about €0.1/W - €100/kW. So our 7.5kWp is €750. A conservative estimate for batteries is €100/kWh. So our 15kWh is €1500. There's obviously other costs - inverters etc. But perhaps the total hardware cost is €3k for 1kW of off-grid solar.

A communications satellite like the Eurostar Neo satellite has a payload power of 22 kW and a launch mass of 4,500 kg. Assuming that's a reasonable assumption, that means about 204kg per kW. Current SpaceX launch costs are circa $1500 per kg - but they're targeting $100/kg or lower. That would give a launch cost of between $300k and $20k per kW of satellite power. That doesn't include the actual cost of the satellite itself - just the launch.

I just don't see how it will make sense for a long time. Even if SpaceX manage to drastically lower launch costs. Battery and solar costs have also been plummeting.

https://www.spaceconnectonline.com.au/manufacturing/4751-air...

https://www.nextbigfuture.com/2025/01/spacex-starship-roadma...

[mike_hearn]

Thanks for the interesting calculations.

Is it reasonable to use Neo as a baseline? Modern Starlink satellites can weigh 800kg, or less than 20% of Neo. I see discussions suggesting they generate ~73kw for that mass. I guess because they aren't trying to blanket an entire continent in signal? Or, why are they so much more efficient than Neo?

Interestingly the idea of doing compute in space isn't a new one, it came up a few years ago pre-ChatGPT amongst people discussing the v2 satellite:

https://forum.nasaspaceflight.com/index.php?topic=58374.msg2...

Still, you make good points. Even if you assume much lighter satellites, the GPUs alone are very heavy. 700kg or so for a rack. Just the payload would be as heavy as the entire Starlink satellite.

[imtringued]

You can't increase the size of the radiator and reduce the mass of the satellite. How is that supposed to work?

You're also forgetting that Starlink satellites aren't in a sun synchronous orbit which means they have to overbuild the energy generation capacity (low capacity factor) and can simultaneously take advantage of earth's shadow to cool down.

[mike_hearn]

Droplet radiators can theoretically do this. The radiator is made up of extremely fine liquid droplets expelled from what is basically a big space shower head. The droplet cloud has a big surface area so more heat can radiate. The droplets are collected in a sort of drain the other side. The idea has been around for decades but there are lots of practical problems to work out, like minimizing losses due to splashes or droplets heading in the wrong direction (e.g. using ferrofluids and magnetic containment). It's never been worked on seriously because conventional radiators were always enough.

With droplet radiators increasing the effective size means using a bigger head/drain and longer booms to expand the distance between them, so the scaling properties are different to pipe based radiators.

[blastro]

Kind of a scary thought - a DC in space can't be stopped by protests or regulation

[elihu]

That could be one reason they want to do it. Maybe by using data from Palantir or harvested from Elon's work with DOGE, along with twitter user data and whatever else they can get, they want their AI to be the all-seeing eye of Sauron. (Which isn't too far from what the whole ad-tech industry is about in the first place.) Or they want to make sexually explicit deepfakes of everyone Elon doesn't like. Or they want to flood the internet with AI generated right-wing propaganda.

[andyjohnson0]

> So I guess the question is - why bother?

This is a Musk escapade, so my guess would be extraterritoriality and absence of jurisdiction.

[UltraSane]

No. With Musk it is always about inflating his share prices.

[fpoling]

If one kilogram of stuff consumes just 100Wt, then in one month it consumes about 300 MJ. So as long as things works for a year or more energy cost to put them into orbit becomes irrelevant.

To keep things in orbit ion thrusters work nicely and require just inert gases to keep them functioning. Plus on a low Earth orbit there are suggestions that a ramjet that capture few atoms of atmosphere and accelerates them could work.

Radiative cooling scales by 4th power temperature. So if one can design electronics to run at, say, 100 C, then calling would be much less problematic.

But radiation is the real problem. Dealing with that would require entirely different architecture/design.

[inglor_cz]

"But why would you?"

Because the permitting process is much easier and there are way, way fewer authorities that can potentially shut you down.

I think this is the entire difference. Space is very, very lightly regulated, especially when it comes to labor, construction and environmental law. You need to be able to launch from somewhere and you need to automate a lot of things. But once you can do this, you escaped all but a few authorities that would hold power over you down on Earth.

No one will be able to complain that your data center is taking their water or making their electricity more expensive, for example.

[oivey]

The satellite is built on Earth, so I’m not sure how it dodges any of those regulations practically. Why not just build a fully autonomous, solar powered datacenter on Earth? I guess in space Elon might think that no one can ban Grok for distributing CSAM?

There’s some truly magical thinking behind the idea that government regulations have somehow made it cheaper to launch a rocket than build a building. Rockets are fantastically expensive even with the major leaps SpaceX made and will be even with Starship. Everything about a space launch is expensive, dangerous, and highly regulated. Your datacenter on Earth can’t go boom.

[mike_hearn]

Truly magical thinking, you say? OK, let's rewind the clock to 2008. In that year two things happened:

- SpaceX launched its first rocket successfully.

- California voted to build high speed rail.

Eighteen years later:

- SpaceX has taken over the space industry with reusable rockets and a global satcom network, which by itself contains more than half of all satellites in orbit.

- Californian HSR has spent over thirteen billion dollars and laid zero miles of track. That's more than 2x the cost of the Starship programme so far.

Building stuff on Earth can be difficult. People live there, they have opinions and power. Their governments can be dysfunctional. Trains are 19th century technology, it should be easier to build a railway than a global satellite network. It may seem truly magical but putting things into orbit can, apparently, be easier.

[oivey]

That’s a strange comparison to make. Those are entirely different sectors and sorts of engineering projects. In this example, also, SpaceX built all of that on Earth.

Why not do the obvious comparison with terrestrial data centers?

[msie]

it should be easier to build a railway

No, because of the costs of acquiring land that the railway goes through.

[ericd]

Now how about procuring half a gigawatt when nearby residents are annoyed about their heating bills doubling, and are highly motivated to block you? This is already happening in some areas.

[inglor_cz]

"fantastically expensive"

From individual POV yes, but already Falcons are not that expensive. In the sense that it is feasible for a relatively unimportant entity to buy their launch services.

"The satellite is built on Earth, so I’m not sure how it dodges any of those regulations practically."

It is easier to shop for jurisdiction when it comes to manufacturing, especially if your design is simple enough - which it has to be in order to run unattended for years. If you outsource the manufacturing to N chosen factories in different locations, you can always respond to local pressure by moving out of that particular country. In effect, you just rent time and services of a factory that can produce tons of other products.

A data center is much more expensive to build and move around. Once you build it in some location, you are committed quite seriously to staying there.

[plorg]

So it's a Zone in search of a use case?

[DonHopkins]

Libertarian Paradise!

Too bad the fire trucks can't get to you when you catch on fire from that hot GPU.

[ericd]

Good thing the lack of oxygen does a pretty good job of taking care of that for you ;-)

[DonHopkins]

And publicly maintained roads.

[wombatpm]

It would make more sense to develop power beaming technology. Use the knowledge from Starlink constellations to beam solar power via microwaves onto the rooftops of data centers

[voidfunc]

Hello SimCity 2000 Microwave Power Plant.

[iFred]

Looking forward to an CNN breaking chyron titled "Oops!"

[habinero]

Why? We have solar panels and fossil fuels at home.

[wookmaster]

Why does that make sense at all

[JeremyNT]

> Why does that make sense at all

Parent said it would make more sense.

I guess in terms of the relative level of stupidity on display, it would be slightly less stupid to build huge reflectors in space than it is to try to build space datacenters, where the electricity can only power specific pieces of equipment that are virtually impossible to maintain (and are typically obsolete within a few years).

[dsr_]

Everybody wants a death ray.

[Findeton]

Maybe they should try to build it in the moon. Difficult, but perhaps not as difficult?

[thephyber]

Almost none of the parent’s bullet points are solved by building on the Moon instead of in Earth orbit.

The energy demands of getting to the 240k mile Moon are IMMENSE compared to 100 mile orbit.

Ultimately, when comparing the 3 general locations, Earth is still BY FAR the most hospitable and affordable location until some manufacturing innovations drop costs by orders of magnitude. But those manufacturing improvements have to be made in the same jurisdiction that SpaceXAI is trying to avoid building data centers in.

This whole things screams a solution in search of a problem. We have to solve the traditional data center issues (power supply, temperature, hazard resilience, etc) wherever the data centers are, whether on the ground or in space. None of these are solved for the theoretical space data centers, but they are all already solved for terrestrial data centers.

[ethbr1]

In situ iron, titanium, aluminum?

[mcny]

But none of those are usable, right? It will take decades of work at least to get a commercial grade mining operation going and even then the iron, titanium, aluminum would need to be fashioned...

Ah, I see the idea now. It is to get people to talk about robotics and how robots will be able to do all this on the moon or wherever.

Instantly pumps Tesla stock here now on earth!

[notahacker]

That's a hard problem to solve. Invest enough in solving that problem and you might get the ability to manufacture a radiator out of it, but you're still going to have to transport the majority of your datacenter to the moon. That probably works out more expensive than launching the whole thing to LEO

[nkrisc]

Sounds more difficult. Not only is the moon further, you also need to use more fuel to land on it and you also have fine, abrasive dust to deal with. There’s no wind of course, but surely material will be stirred up and resettle based on all the landing activity.

And it’s still a vacuum with many of the same cooling issues. I suppose one upside is you could use the moon itself as a heat sink (maybe).

[microtherion]

> Not only is the moon further, you also need to use more fuel to land on it

And take off again, if reusable spacecraft are meant to be used.

[sdenton4]

The 2.5s round trip communication latency isn't going to be great for chat. (Alongside all the other reasons.)

[zbentley]

And 2.5s is best case. Signal strength issues, antenna alignment issues, and all sorts of unknown unknowns conspire to make high-integrity/high-throughput digital signal transmissions from a moon-based compute system have a latency much worse than that on average.

[kakacik]

Yeah, carrying stuff 380k km and still deploying in vacuum (and super dusty ground) doesn't solve anything but adds cost and overhead. One day maybe, but not these next decades nor probably this century.

[AllegedAlec]

Still a vacuum so the same heat dissipation issues, adding to it that the lunar dust makes solar panels less usable, and the lunar surface on the solar side gets really hot.

[ahoka]

It has all these problems, plus more.

[cogman10]

> I also strongly suspect, given some background reading, that radiator tech is very far from optimized. Most stuff we put into space so far just doesn't have big cooling needs, so there wasn't a market for advanced space radiator tech. If now there is, there's probably a lot of low hanging fruit (droplet radiators maybe).

You'd be wrong. There's a huge incentive to optimized radiator tech because of things like the international space station and MIR. It's a huge part of the deployment due to life having pretty narrow thermal bands. The added cost to deploy that tech also incentivizes hyper optimization.

Making bigger structures doesn't make that problem easier.

Fun fact, heat pipes were invented by NASA in the 60s to help address this very problem.

[zero_bias]

ISS and MIR combined are not a "large market". How many radiators they require? Probably a single space dc will demand a whole orders of magnitude more cooling

[cogman10]

ISS cost $150B and a large factor driving that cost was the payload weight.

Minimizing payload at any point was easily worth a billion dollars. And given how heavy and nessisary the radiators are (look them up), you can bet a decent bit of research was invested in making them lightweight.

Heck, one bit of research that lasted the entire lifetime of the shuttle was improving the radiative heat system [1]. Multiple contractors and agencies invested a huge amount of money to make that system better.

Removing heat is one of the most researched problems of all space programs. They all have to do it, and every gram of reduction means big savings. Simply saying "well a DC will need more of it, therefore there must be low hanging fruit" is naive.

[1] https://llis.nasa.gov/lesson/6116

[mike_hearn]

The ISS is a government project that's heading towards EOL, it has no incentive to heavily optimize anything because the people who built it don't get rich by doing so. SpaceX is what optimization looks like, not the ISS.

[cogman10]

> has no incentive to heavily optimize anything because the people who built it don't get rich by doing so.

Optimization is literally how contractors working for the government got rich. Every hour they spent on research was directly billed to the government. Weight reduction being one of the most important and consistent points of research.

Heck, R&D is how some of the biggest government contractors make all their dough.

SpaceX is built on the billions in research NASA has invested over the decades. It looks like it's more innovative simply because the USG decided to nearly completely defund public spending in favor of spending money on private contractors like SpaceX. That's been happening since the 90s.

[jeltz]

By the same token SpaceX has no reason to optimize Starship. That is also largely a government project.

[b112]

It's a private company, is profit motivated, and thus has reason to optimize. That was the parent poster's point.

Starship isn't largely a government project. It was planned a decade before the government was ever involved, they came along later and said "Hey, this even more incredible launch platform you're building? Maybe we can hire SpaceX to launch some things with it?"

Realistically, SpaceX launches far more payload than any government.

[oivey]

Lockheed, Boeing, Northrop, Raytheon, and all the others are private companies, too. NASA and others generally go through contractors to build things. SpaceX is on the dole just like them.

[habinero]

Haha no. SpaceX survives entirely on money from the US government. It's always been that way.

[lightedman]

Entirely? lol not even close.

Source: I am out of LEDs and LASERs and now handle aerospace solar for a private company. Guess who almost everyone in the private sector flies on?

[s-y]

Where are you getting this from?

[thinkcontext]

A puzzling statement, could you explain? Most of their revenue now comes Starlink which is mostly private clients. Also it's trivial to look at their launch history and see they have plenty of private clients. For sure the USG is their most important client but "entirely" is flat out wrong.

[pineaux]

that is true. They would have failed after their first failed launch. The US government saved them.

[skywhopper]

All of those “huge overheads” you cite are nothing compared to the huge overhead of building and fueling rockets to launch the vibration- and radiation-hardened versions of the solar panels and GPUs and cooling equipment that you could use much cheaper versions of on Earth. How many permitted, regulated launches would it take to get around the one-time permitting and predictable regulation of a ground-based datacenter?

Are Earth-based datacenters actually bound by some bottleneck that space-based datacenters would not be? Grid connections or on-site power plants take time to build, yes. How long does it take to build the rocket fleet required to launch a space “datacenter” in a reasonable time window?

This is not a problem that needs to be solved. Certainly not worth investing billions in, and definitely not when run by the biggest scam artist of the 21st century.

[thephyber]

There is a lot of hand waiving away of the orders of magnitude more manufacturing, more launches, and more satellites that have to navigate around each other.

We still don’t have any plan I’ve heard of for avoiding a cascade of space debris when satellites collide and turn into lots of fast moving shrapnel. Yes, space is big, but low Earth orbit is a very tiny subset of all space.

The amount of propulsion satellites have before they become unable to maneuver is relatively small and the more satellite traffic there is, the faster each satellite will exhaust their propulsion gasses.

[krisoft]

> We still don’t have any plan I’ve heard of for avoiding a cascade of space debris when satellites collide and turn into lots of fast moving shrapnel.

What do you mean we don’t have any plans to avoid that? It is a super well studied topic of satelite management. Full books have been written on the topic.

Here is just one: https://ntrs.nasa.gov/api/citations/20230002470/downloads/CA...

Did you think satelites are kept apart by good luck and providence?

[thephyber]

I am very aware that the US Air Force / Space Force monitor’s trajectories and calls satellite owners when there is an anticipated collision but that method doesn’t scale, especially with orders of magnitude more satellites in the same LEO shells.

And it still doesn’t solve the problem of a cascade causing shrapnel density to increase in an orbit shell which then causes satellites to use some of their scarce maneuver budget to avoid collision. But as soon as a satellite exhausts that budget, it becomes fodder for the shrapnel cascade.

[turtlesdown11]

>There is a lot of hand waiving away of the orders of magnitude more manufacturing, more launches, and more satellites that have to navigate around each other.

This is exactly like the Boring Company plans to "speed up" boring. Lots of hand waving away decades of commercial boring, sure that their "great minds" can do 10x or 100x better than modern commercial applications. Elon probably said "they could just run the machines faster! I'm brilliant".