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Uh, okay. Manhattan has an area of 20 square miles. What's the relevance to space radiators?
Hmm. What is StarThink?
I think it's quite clear that mass is not the concern I raised wrt the size of the radiators, which is why my post did not say anything about mass. Huge radiators cause drag and are vulnerable to micrometeorites. Redundant cooling loops can mitigate micrometeorites, but then you need bigger radiators.
But since you brought it up - the radiator you posted is solid state, SpaceX says they will use circulating liquid radiators, same for starcloud. I expect this is because circulating liquid radiators scale more than passive radiators like the one you are looking at. Just a guess on my part, though.
Now, StarCloud says each data center will be 5GW. They are cagey about how exactly they will dissipate 5GW, but with a simple water/glycol loop we are looking at 50,000 kg/s of flow which is massive. All those pumps will of course also need to be cooled.
On top of that, the radiators need to be filled with coolant. Back of the envelope math, again for a simple coolant loop, suggests perhaps 100,000 tons of coolant in the radiator, so we're looking at $10B just to get the coolant up there across hundreds of launches and nothing else. They do not go into the math of this in their whitepaper, probably because single phase liquid coolant is totally infeasible.
Tedious bluster. Please save it for Twitter.
It matters because it deflates the context-free appeal to "omg 2000 square meters". Ok. 2000 square meters is just 40 * 50 meters. Is this supposed to be a lot?
It's not clear, because mass is the only interesting concern there is. Drag, too, is an issue of mass (for ion thruster fuel). Your link says: "And that’s the best-case scenario. Additional problems are hidden in the low Earth orbit environment itself. Space exposes radiators and their coatings to a chemically hostile brew of ultraviolet light and atomic oxygen, quite the opposite of a clean-room environment. Over a LEO satellite’s typical 5-year lifespan, these elements degrade the radiator’s surface properties and lower its ability to shed heat. … Including this degradation in the model reveals that as the radiator degrades from a “fresh” state to an “end-of-life” state, the physics demands a further penalty. To maintain that same 60 °C operating temperature for the GPU chips, the required surface area jumps from about 1.4 square meters per chip to nearly 2.0 square meters. In other words, the physics tax rises by 40 percent. Therefore, you must launch at least 40 percent more radiator mass, endure higher atmospheric drag, and sacrifice valuable launch volume just to survive the degradation of the thermal coating."
Or you can simply launch a little higher. No matter how you cut it, it's all ultimately about mass.
Huge solar panels cause drag and are also vulnerable to micrometeorites. This issue, just like the radiator issue, is negligible. Neither solar panels nor radiators lose function quickly from random point damage. At, say, 500 km the lifetime of an inference node with several thousand square meters of total area can be a decade. How much economic value does a decade of compute with free power provide? That, cost per kilogram to orbit, and costs of hardware are all that matters.
Since you dislike X, I'll cite it again. NVIDIA CEO JENSEN HUANG: 1GW AI FACTORY ON NVIDIA ARCHITECTURE COULD COST NEARLY $100 BILLION
So, maybe $450B for that 5 GW you talked about. Cooling alone is likely a fifth of that. I guess popular reporting can create the impression that Americans are actually standing up tens of gigawatts of capacity without problem, like so much coal plants in China. This is not, in fact, happening. Most Blackwell compute is still not operational. All this space math only matters in relations to costs on Earth.
I hope I didn't mislead anyone into believing that 2000 square meters is a megastructure. Nevertheless, most people have never seen an Ascend 950 so I don't think that helps contextualize anything for anyone. 2000 sq m is fairly large for a space radiator - the ISS has only about 400 sq m.
Perhaps. And yet, Starcloud plans to operate in LEO. I assume they aren't totally retarded and have thought through the choice of orbit. It's difficult to have a discussion about this when you ignore the details from the actual proposals in favor of advocating for stuff they aren't doing when it's convenient. Either the people working on this are smart and have chosen the best parameters for this, or they are stupid to the point that the internet peanut gallery can do better and therefore aren't going to succeed. You must pick one.
If you're pumping coolant through a tube that's open to vacuum, you're going to have some problems.
I don't really understand what drives a man to repost second hand all caps claims. I'm not even saying that he didn't say this, but surely you must understand that this is simply not convincing to anyone?
Space based DCs also fail the "not currently happening" test, so this part is a wash.
You know what, fair enough. Let's ignore Starcloud since this is primarily about SpaceX. They've just issued a concrete design: Starmind
• 150 kW peak compute payload
• 120 kW average compute payload
• 70 kW per ton
• Wingspan: 70 meters
• Deployed height: 20 meters
• 110 m² deployable liquid radiator
• Redundant pumping loops
• Integrated micrometeoroid shielding
• 150 kW solar array
• 250 W/m²
• High-speed laser links interconnect satellites and beam AI results back to Earth through Starlink. Low-latency, high-bandwidth connection
• SpaceX-manufactured solar technology from Bastrop, Texas
So, that's 917 square meters of radiator per 1 (sustained) megawatt, and more importantly 70 kW of capacity per ton, at SSO. I see Starship has the theoretical capacity of 40-60 tons to SSO, let's say 50. At, say, $200/kg that's $8M to deliver 2.8 MW of compute. As per Jensen, 1 MW can go for $100M. There's plenty of slack in this. Even if Jensen is off by an order of magnitude, the "getting it into space" part is almost a rounding error and can make straightforward sense given terrestial/political constraints.
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I was too lazy to de-caps it, and I hope that people of this forum will find the issue of the costs of 1 gigawatt of capacity on Earth more salient than the funny detail about all caps.
Problems of space compute have straightforward engineering solutions, the costs of which can be estimated. Whether these solutions are worth the cost depends on the costs of building the same capacity on Earth. So arguments about radiator area, micrometeorite damage or coolant mass are kind of… weightless unless grounded in comparison to the baseline.
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