"It really seems like anyone with some renders and a white paper written by someone being gassed up by an overly agreeable AI can get VC funding these days."
Radiators work because they have something to radiate heat into. Space is famously empty, so a radiator the size of a planet would only work as a heat sink until the total heat in the system was high enough to make everything glow like a heating element, at which point you dump waste energy as visible light.
You can radiate heat into the vacuum of space, it’s just extremely slow compared to doing it into atmosphere. Vacuum is not a perfect insulator in this regard.
Think of it this way, if a vacuum was a perfect insulator, how would the sun radiate heat to Earth?
Radiators work because they have something to radiate heat into. Space is famously empty, so a radiator the size of a planet would only work as a heat sink until the total heat in the system was high enough to make everything glow like a heating element, at which point you dump waste energy as visible light.
You can radiate heat into the vacuum of space, it’s just extremely slow compared to doing it into atmosphere. Vacuum is not a perfect insulator in this regard.
Think of it this way, if a vacuum was a perfect insulator, how would the sun radiate heat to Earth?
The radiators dissipate the heat as infrared radiation. They work as long as they are pointed away from the sun or earth.
If they couldn’t get rid of the heat, there would be no satellites or space stations.