Comment by eldenring
13 hours ago
these same comments pop up every time someone brings up satellite data-centers where people just assume the only way of dissipating heat is through convection with the environment.
13 hours ago
these same comments pop up every time someone brings up satellite data-centers where people just assume the only way of dissipating heat is through convection with the environment.
No, we just "assume" (i.e. know) that radiation in a vacuum is a really bad way of dissipating heat, to the point that we use vacuum as a very effective insulator on earth.
Yes, you can overcome this with enough radiator area. Which costs money, and adds weight and space, which costs more money.
Nobody is saying the idea of data centers in space is impossible. It's obviously very possible. But it doesn't make even the slightest bit of economic sense. Everything gets way, way harder and there's no upside.
> No, we just "assume" (i.e. know) that radiation in a vacuum is a really bad way of dissipating heat, to the point that we use vacuum as a very effective insulator on earth.
In space or vacuum radiation is the best way to dissipate heat, since it's the only way.
I believe the reason the common person assumes thermal radiation is a very poor way of shedding heat is because of 2 factoids commonly known:
1. People think they know how a vacuum flask / dewar works.
2. People understand that in earthly conditions (inside a building, or under our atmosphere) thermal radiation is insignificant compared to conduction and convection.
But they don't take into account that:
1) Vacuum flasks / dewars use a vacuum for thermal insulation. Yes and they mirror the glass (emissivity nearer to ~0) precisely because thermal radiation would occur otherwise. They try their best to eliminate thermal radiation, a system optimized to eliminate thermal radiation is not a great example of how to effectively use thermal radiation to conduct heat. The thermal radiation panels would be optimized for emissivity 1, the opposite of whats inside the vacuum flask.
2) In a building or under an atmosphere a room temperature object is in fact shedding heat very quickly by thermal radiation, but so are the walls and other room temperature objects around you, they are reheating you with their thermal radiation. The net effect is small, in these earthly conditions, but in a satellite the temperature of the environment faced by the radiating surfaces is 4K, not a temperature similar to the object you are trying to keep cool.
People take the small net effect of thermal radiation in rooms etc, and the slow heat conduction through a vacuum flasks walls as representative for thermal radiation panels facing cold empty space, which is the mistake.
Well no, it’s because conduction/convection into a fluid is so much more effective.
Just look at a car. Maybe half a square meter of “radiator” is enough to dissipate hundreds of kW of heat, because it can dump it into a convenient mass of fluid. That’s way more heat than the ISS’s radiators handle, and three orders of magnitude less area.
Or do a simple experiment at home. Light a match. Hold your finger near it. Then put your finger in the flame. How much faster did the heat transfer when you made contact? Enough to go from feeling mildly warm to causing injury.
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Additional radiator area means bigger spacecraft, implies more challenge with attitude control. Lower down you get more drag so you use propellant to keep yourself up, higher up you have more debris and the large area means you need to frequently manoeuvre to avoid collisions. Making things bigger in space is not trivial! You can't just deploy arbitrarily large panels and expect everything to be fine.
space is vast
they could go near a Lagrange point
there are so many options
heavier boats are also slower to accelerate or decelerate compared to smaller boats, does this mean we should ban container ships? having special orbits for megastructure lanes would seem a reasonable approach.
The radiators would be lighter compared to the solar panels, and slightly smaller surface area so you can line them back to back
I don't think dissipating heat would be an issue at all. The cost of launch I think is the main bottleneck, but cooling would just be a small overhead on the cost of energy. Not a fundamental problem.
If you solved this problem apply at nasa because they still haven't figured it out.
Either that or your talking out of your ass.
FYI a single modern rack consumes twice the energy of the entire ISS, in a much much much much smaller package and you'll need thousands of them. You'd need 500-1000 sqm of radiator per rack and that alone would weight several tonnes...
You'll also have to actively cool down your gigantic solar panel array
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The pertinent thing is that it’s not an advantage. It may be doable but it’s not easier than cooling a computer in a building.
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