[hparadiz]

The video they posted today outlines their specs. They are gonna be smaller. About 100T. Based on Starlink architecture but with way larger radiators and solar panels. Apparently the design is simpler than existing Starlinks because it has fewer different parts.

Specs: https://x.com/SawyerMerritt/status/2064108916611420273?s=20

[amluto]

That cooling system is … aggressive. 110m^2 of radiator to dissipate 120kW average heat. That’s about 1.1kW/m^2, which works out to very close to 100C at the radiator under absolutely perfect conditions (absolute zero ambient temperature, emissivity 1, no adverse geometric effects).

Radiating into 300K ambient, it’s 134C. (300K ambient is about what you get if the sun is visible or if a large fraction of what the radiator can see is the Earth.)

You can slightly fudge the 300K case with a spatially or specially selective system, which would add weight and complexity. (Well, you can’t get rid of the problem of the Earth being warm by spectral selectivity — it’s the same spectrum as the radiator.) You cannot fudge the absolute zero case — the Stefan-Boltzmann law is extremely unforgiving. [0] And you need some headroom for the system that gets the cooling fluid to the radiator.

The thermal qualification temperature of an H100 is 87C and the associated HBM is 95C.

So I don’t see how this can work short of using higher-temp chips. I have no idea how SpaceX expects to source any such thing in any meaningful volume.

[0] This includes heat pumps. A heat pump makes it worse.

[yread]

Maybe they count them twice? That would work out to 41C if both sides are in shade (or 69C if one is shaded and one on the sunny side)

[hparadiz]

I assume the radiators will be in the shadow behind the solar panels and never facing the sun. That's seems like the easiest quick win.

[amluto]

This isn’t that big a win. If you put the radiator in the shadow of the solar panels then a good fraction (which depends on the geometry) of the radiated heat from the side facing the panels hits the panels and warms the panels, and the radiated heat from the back of the panels warms the radiator. And the panels themselves are less efficient when they’re warmer.

On the flip side of all this, the Starlink satellites work, and I would expect SpaceX to have some idea what they’re doing. Starlink satellites have largish power systems (smaller than these proposed AI satellites, but not outrageously so). They presumably turn a smaller fraction of their power into low-temperature heat: the ion thrusters and the various transmitters emit a good deal of non-thermal power. A good fraction of Starlink’s electronics way well function at rather higher junction temperatures than 100C. And I imagine that Starlink satellites are economical to operate at an average of much less than 100% power. So I don’t really know what’s going on. It’s plausible that Starlink gets away with a cooling system that’s not so great for a compute satellite.

[fc417fc802]

Is the equilibrium temperature in orbit not somewhere between freezing and room temperature? If so spreading the heat evenly across the solar panels must necessarily be sufficient. Issues only arise if you try to get away with a smaller radiator or expose the radiator to direct sunlight or commit some other own goal.

[orwin]

The radiators then need to be protected from earth's heat/light if you want to reach 0K. I agree with GP, it doesn't seem great.

[pryce]

I feel like we are going to relive the hyperloop-decline with the specs of proposed orbital datacentres. But the hyperloop was in one regard a success, in that it built temporary hype. Maybe it was even named after that.

[sylos]

The hyperloop was a huge success...in delaying actual transit options like trains.

[lelandfe]

What, you don't have a Tesla elevator on your street yet? https://www.youtube.com/watch?v=j70GvgXt-lE

[SwellJoe]

It also achieved Musk's actual goal: derailing and delaying mass transit initiatives, the California High-speed Rail project, in particular.

He knew it was bullshit. He's dumber than most people realize, but he's not dumb enough to actually believe all the bullshit he spouts.

[hparadiz]

He's sending the weirdest mixed signals. If we want to hit anywhere near 1 on the Kardashev scale we're gonna need a planet wide high speed rail system. They should just give the major tech companies naming rights to the stations for 35 years for like 2-3 billion a pop and scale up construction 5x.

I don't get the slow roll on this thing. The stations in LA and SF are gonna end up sort of like Tokyo station for the Shinkansen. A giant mall area with a huge amount of commerce. Why isn't this thing done yesterday?

[SwellJoe]

He doesn't actually want progress. He wants power and wealth for himself. Public transit is an equalizer, it serves normal people.

[hparadiz]

Relax man. He's a bipolar weirdo who isn't always likable but progress doesn't always come from likeable people. And the fact of the matter is he has actually delivered on a bunch of stuff I thought I'd never see in my lifetime.

[SwellJoe]

What kinds of things he's delivered do you have in mind?

[nine_k]

> Why isn't this thing done yesterday?

Land rights. Environmental reviews. Various suits attempting to exert extra compensations for tangential (at best) issues. Basically the California around.

[ianburrell]

Planet wide high speed rail doesn't make much sense, it is better of medium sized trips. Flights are will always be better for intercontinental trips. Vacuum trains could be faster but would be so expensive to build. Issues would be big deal in evacuated tunnels.

CA HSR is slow partly because the state government has limited funds and giving out slowly. The federal government should have been contributing more. The other problem is it kept getting delayed from legal issues, mainly from acquiring land. Going forward is bad because they decided to do the easy part first and leave the hard tunnels for later.

[WalterBright]

> Vacuum trains could be faster but would be so expensive to build

Vacuum trains are what high altitude airliners are.

[cryptonector]

Nooo, not thaaat!! We want traiiiins!!

[hparadiz]

There should be a high speed rail for every minor leg along the way. Efficiency is relative. People should be able to ship their car by this system instead of renting if they chose. Or use it to go sight seeing in any direction along it's web. The whole point is freedom to move around.

The cost of the HSR is tiny and inconsequential. For the 40 million residents of California it amounts to about $20 a month over the 10 years the fund has been going. It hasn't even spent 50% of the total fund yet. If construction was even 2x the current rate we would already have the central valley done. So I know they are slow rolling it. That's my point. They can speed things up even just a little.

[NortySpock]

Orbital ring would kickstart the space economy like nothing else, and is technically achievable with existing materials.

[fc417fc802]

Would you trust the operators of an orbital ring with your life though? The modern world seems to mostly be able to do sky scrapers at this point but ... ehh. We still struggle a bit even with just airliners.

[hparadiz]

Both?!? Both.

[dilyevsky]

Pinning CAHSR jobs program as hyperloop's fault is pretty funny. Maybe he did intend to upset it but since both turned out to be massive boondoggles doesn't seem like it worked - they managed to delay it themselves just fine.

[SwellJoe]

Sure, California is a failed state on a lot of fronts, but Musk literally said he was pushing hyperloop for that reason. https://www.fresnobee.com/opinion/editorials/article26445107...

Whether he was the only reason for high speed rail being derailed and delayed isn't really the point. He intentionally worked against mass transit, and lied repeatedly about hyperloop as part of that.

[flomo]

Certainly not a Musk fan, but IMO the real point of hyperloop was more that it's on a route that could be constructed within our lifetimes. (Unlike CAHSR, check their website.) Of course, California knows this because that's where they built Interstate 5.

[hparadiz]

> California is a failed state on a lot of fronts

Some people really should just rm -rf their boot disk cause I feel dumber for having read their comment.

[SwellJoe]

The feeling is mutual.

[dilyevsky]

I think you've missed the point - that wasn't the reason at all. In a way he was right too - we'll have fully autonomous buses and private vehicles capable of making the full trip down the I-5 long before they complete even the middle of nowhere section they currently have planned.

[SwellJoe]

Autonomous buses and private vehicles don't solve any of the problems high speed rail solves.

[NordStreamYacht]

I don't think he's dumb at all, if what you say is correct. He wanted to block something for his own benefit and he achieved it.

[bulbar]

I'm not convinced that's the case. I tend to think he just saw something he found cool and triggered his narcissism so he had to come up with something he thought was cooler. That something turned out to be BS and he just dropped the idea and moved on.

[hparadiz]

That's exactly what happened lol.

[bulbar]

The behavior of both Musk and Trump is easily (and sometimes obviously) explained in terms of narcissism.

Nobody talks about it, but my pet theory is that Trunk attacked Iran because he wanted to do it in his first terms but was stopped by his inner circle. THE Trump. Stopped. Of course he loved the idea of attacking Iran when presented to him earlier this year.

People tend to think that the powerful and rich are so much more clever than normal people so they come up with complex hidden agendas, but I didn't find it necessarily being the case.

[SwellJoe]

He is ruthlessly cunning. Not unusual in sociopaths and narcissists.

[themafia]

> the California High-speed Rail project

The state government of California was doing a bang up job of destroying this project on their own. He didn't really need to help them. Moreover given the rise of remote work I'm not sure it has as much value as it would have had it been constructed when it was designed.

> but he's not dumb enough to actually believe all the bullshit he spouts.

Yet he's not afraid of the consequences either. This seems more telling to me.

[SwellJoe]

The consequence of becoming the world's richest man? Oh, the horror. The very wealthy do not face consequences for their actions.

He lies every day about his companies, and no one ever does a thing about it.

DOGE killed a few hundred thousand children for no reason at all; it didn't even save money. He did it purely for the joy of killing black and brown children in the global south. No one with any power to deliver has ever suggested he should face consequences for it.

Why should he be afraid of consequences? There will never be any for him, as long as he is protected by unimaginable wealth and a power structure designed around serving those with wealth.

[sumeno]

He has never faced an actual meaningful consequence, of course he isn't afraid of them.

[mayama]

After articles on how starship is never getting off launchpad, I'm sceptical of news regarding elon, pro and anti. Sure, things like FSD are hopium or scam, but not everything could be. Haven't seen hard science estimates on their new ai satellites.

[zarzavat]

The issue with AI datacenters in orbit is not science or engineering but economics. There is no practical reason why it can't be done, but why would anyone want to buy compute from such a datacenter when they could pay substantially less money for better capacity on Earth?

Orbit is a bad place for a datacenter. Your equipment will be hot and bombarded with radiation. You can't do any repairs. Even with reusable rockets you still have to pay for fuel to launch everything into orbit. You get a small benefit of more efficient power generation but it's not worth all the downsides.

If you want to have solar-powered AI datacenter that you can't service, you'd be way better off building the power generation in a coastal desert and building your datacenter underwater.

[tyre]

With the rockets, it was more, “wow that seems impossible, but incredible if you can pull it off versus existing options.”

With the space data centers, it’s more, “Okay yeah so let’s say you do…why?”

It just seems like a really hard thing to do when the available options are, like, the Chinese building data centers on the Tibetan plateau where it is cold, ample renewable energy, tons of land, and, like, oxygen.

[ianburrell]

150 kW is tiny, that is a single rack. Would have to launch a huge number of them to match the GW data centers being built. There is also a lot of overhead for each one.

If Starlink didn't exist, then it could make sense to put edge data centers in orbit. But Starlink means can put edge computing everywhere on the ground.

[asadotzler]

In 2025, SpaceX put 3,200 Starlink satellites into orbit with 122 Falcon 9 launches. That's about 2,000 tonnes. In about 2 more years, as the Starlink constellation reaches its licensed size limit, it should transition from growth mode to maintenance mode, freeing up over 1,000 tonnes of extremely reliable launch capacity.

What could that 1,000 tonnes per year get your in terms of sell-able data center capacity, and how does that compare to terrestrial build-out time frames?

[ac29]

According the the X post, each 150kW satellite is a bit over 2 tons, so a full year of launches would get you 75MW. Thats not much when AI datacenters are GW-class.

[skybrian]

Would it make any sense for it to orbit next to a Starlink satellite?

[Zigurd]

That projection depends on packaging and cooling breakthroughs that we would already be seeing in terrestrial data centers if they were practical.