Comment by wkat4242
1 day ago
Yes cooling is difficult. Half the "solar panels" on the ISS aren't solar panels but heat radiation panels. That's the only way you can get rid of it and it's very inefficient so you need a huge surface.
1 day ago
Yes cooling is difficult. Half the "solar panels" on the ISS aren't solar panels but heat radiation panels. That's the only way you can get rid of it and it's very inefficient so you need a huge surface.
This isn’t true. The radiators on ISS are MUCH smaller than the solar panels. I know it’s every single armchair engineer’s idea that heat rejection is this impossible problem in space, but your own example of ISS proves this is untrue. Radiators are no more of a problem than solar panels.
The radiators are significantly smaller than the PV arrays, but not by a massive ratio; looks like about 1:3.6 based on the published area numbers that I could find.
It looks like the ISS active cooling system has a maximum cooling capacity that could handle the equivalent of a single-digit number of racks (down to 1 for an AI-focused rack).
if you were looking at a 10' tall spider and a 36' tall spider, yes they'd both be big but it'd be fair to say that the 10' one is much smaller....
The heat load of the ISS is a handful of astronauts and some equipment and whatever it absorbs from the sun. Not an entire data center or a nuclear rocket which is where the radiator discussion comes into play.
The heat load is equal to the load from the solar panels, to first order. So actually yeah, you CAN compare the size of solar panels to the size of the radiators.
seems oddly paradoxical. ISS interior at some roughly livable temperature. Exterior is ... freakin' space! Temperature gradient seems as if it should take of it ...
... and then you realize that because it is space, there's almost nothing out there to absorb the heat ...
There's nothing paradoxical about it. There's no such thing as a temperature gradient in a vacuum, there's nothing to hold or measure temperature against. And thus a vacuum is a really good insulator. Which is why a vacuum flask, which ultimately became one of Thermos' most well known products, is used to control temperature both in and outside the lab.
Except a thermos has a really low emissivity, otherwise (if it had high emissivity), it’d be a poor insulator due to thermal radiation, the same reason why ISS’s radiators are much smaller than its solar panels.
there literally is nothing to absorb the heat. Conduction and convection are out, all you got is radiation.
new vc rule: no investing in space startups unless their founders have 1000 hours in KSP and 500 hours in children of a dead earth
I’d settle for at least a high school physics education. This idea seemed insane when I first heard about it a few weeks back. This analysis just makes it that much more crazy.
If YC is hell bent on lighting piles of money on fire, I can think of some more enjoyable ways.
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Radiation is not actually a problem unless you're trying to do super high power nuclear electric propulsion (i.e. in your videogame). Classic armchair engineer mistake, tbh.
Radiators work great in space. Stefan-Boltzmann's law. The ISS's solar panels are MUCH smaller than the radiators. Considering datacenters on Earth have to have massive heat exchangers as well, I really think the bUt wHaT aBoUt rAdiAtOrs is an overblown gotcha, considering every satellite still has to dump heat and works just fine.
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A great interactive example of this is the game Oxygen Not Included. By the late game, you're biggest problem is your base getting too hot from the waste heat of all your industry.