Let’s say the “space datacenter” peaks at 500 megawatts, seeing how Earth ones apparently peak around this. But that includes stuff like waste heat from power generation, the cooling and comms system, eveything on the spacecraft.
Lets say we want the coolant at 60C, so the computing stuff stays under 80C, as I am trying to give this system the benefit of the doubt. And lets assume the radiator is quite efficient and ignore mere engineering concerns, and give it an overall emissivity of 0.8.
From Project Rho:
Radiator area = P / (ε * σ * T^4)
Radiator area = (10 ^ 8 W) / ((0.8 emissivity) * (5.670374419 *10^-8, boltzman constant) * (333 Kelvin ^ 4, the same as 60C))
…That’s a radiator two thirds of a mile across.
Let’s, again, toss practicality out the window and say the “weight” of the whole thing is similar to a 6 mm aluminum panel, which seems like an unreasonable feat of engineering. After all, we gotta pump liquid through the thing, and unfold it somehow. But lets go with it.
That’s 5400 cubic meters of aluminum. That’s 5.6 * 10^6 kilograms. Picture a cargo ship flattened into a disk; that’s the order of mass we’re talking about.
At 20,000 kg per flight… that’s 112 Falcon Heavy flights to low earth orbit, or ~$10 billion dollars. Just to get our impossible radiator into orbit, and nothing else. Lets say launch costs get 10X cheaper, somehow, and that’s still a billion dollars.
That’s 5400 cubic meters of aluminum. That’s 5.6 * 10^6 kilograms. Picture a cargo ship flattened into a disk; that’s the order of mass we’re talking about.
Deorbiting it would probably make for an exciting show. Also, I wonder how much aluminum you can dump into the atmosphere before you have effects.
Within 15 years, plummeting satellites could release enough aluminum to alter winds, temps in the stratosphere
Estimates suggest satellite debris could rival the amount of naturally occurring meteor dust in the atmosphere by 2040.
At that rate, a satellite would burn up in the atmosphere every one to two days, depositing 10,000 metric tons of alumina in the upper atmosphere. That’s equivalent to about 150 space shuttles vaporizing in the atmosphere every year.
The new study, published in the Journal of Geophysical Research: Atmospheres, suggests that much alumina could alter polar vortex speeds, heat up parts of the mesosphere by as much as 1.5 degrees Celsius, and impact the ozone layer. The metal aerosols and other particles vaporized from falling satellites would likely circulate in the stratosphere for several years, according to the authors.
Spacecraft have a lot of exotic material in them, right? I guess aluminum is the big one by mass, but I bet there’s enough of others for interesting effects, too.
Well, in 2022 Qtar spent $220b to have some football matches in the desert… and didn’t the cost of launching stuff on orbit substantially decreased in the last decade? Again, give a few decades, technology makes everything easier. If you were making that same math just ten years ago, your 10x cheaper would be the estimate you reached now.
This was a totally unrealistic estimate, it’s probably more like trillions of R&D and launches. But even if it’s not, why on Earth would anyone spend that money when it’s so easy to and cheap to put data centers on Earth? We have tons of land! We have tons of space for making energy! And ocean! We can swap the servers out when they go obsolete in a few years! What’s the benefit to putting this same stuff in space?
It’s like discussing orbital, beamed solar power when land-based solar arrays are dirt cheap, yet barely getting funded as is. It’s an interesting thought experiment on using the higher solar flux, yes, and it abruptly ends when you start to consider practicality.
Right now Japan is finding easier to have outsourced people operating robots in convenience stores than hiring some local… like, when you add the cost of the robot, its maintenance, and you still have to pay someone to operate it… I also don’t know why.
Let’s do math.
Let’s say the “space datacenter” peaks at 500 megawatts, seeing how Earth ones apparently peak around this. But that includes stuff like waste heat from power generation, the cooling and comms system, eveything on the spacecraft.
Lets say we want the coolant at 60C, so the computing stuff stays under 80C, as I am trying to give this system the benefit of the doubt. And lets assume the radiator is quite efficient and ignore mere engineering concerns, and give it an overall emissivity of 0.8.
From Project Rho:
Radiator area = P / (ε * σ * T^4)
Radiator area = (10 ^ 8 W) / ((0.8 emissivity) * (5.670374419 *10^-8, boltzman constant) * (333 Kelvin ^ 4, the same as 60C))
…That’s a radiator two thirds of a mile across.
Let’s, again, toss practicality out the window and say the “weight” of the whole thing is similar to a 6 mm aluminum panel, which seems like an unreasonable feat of engineering. After all, we gotta pump liquid through the thing, and unfold it somehow. But lets go with it.
That’s 5400 cubic meters of aluminum. That’s 5.6 * 10^6 kilograms. Picture a cargo ship flattened into a disk; that’s the order of mass we’re talking about.
At 20,000 kg per flight… that’s 112 Falcon Heavy flights to low earth orbit, or ~$10 billion dollars. Just to get our impossible radiator into orbit, and nothing else. Lets say launch costs get 10X cheaper, somehow, and that’s still a billion dollars.
Deorbiting it would probably make for an exciting show. Also, I wonder how much aluminum you can dump into the atmosphere before you have effects.
kagis
Oooh.
https://csl.noaa.gov/news/2025/427_0428.html
That’s fascinating.
Spacecraft have a lot of exotic material in them, right? I guess aluminum is the big one by mass, but I bet there’s enough of others for interesting effects, too.
Well, in 2022 Qtar spent $220b to have some football matches in the desert… and didn’t the cost of launching stuff on orbit substantially decreased in the last decade? Again, give a few decades, technology makes everything easier. If you were making that same math just ten years ago, your 10x cheaper would be the estimate you reached now.
But why?
This was a totally unrealistic estimate, it’s probably more like trillions of R&D and launches. But even if it’s not, why on Earth would anyone spend that money when it’s so easy to and cheap to put data centers on Earth? We have tons of land! We have tons of space for making energy! And ocean! We can swap the servers out when they go obsolete in a few years! What’s the benefit to putting this same stuff in space?
It’s like discussing orbital, beamed solar power when land-based solar arrays are dirt cheap, yet barely getting funded as is. It’s an interesting thought experiment on using the higher solar flux, yes, and it abruptly ends when you start to consider practicality.
Right now Japan is finding easier to have outsourced people operating robots in convenience stores than hiring some local… like, when you add the cost of the robot, its maintenance, and you still have to pay someone to operate it… I also don’t know why.
That’s pretty interesting. I guess the candidate pool may be close to zero (and highly unreliable) in certain places.