Comment by mlyle

> I do not believe that you can make an efficient radiation heatsink with metallic foil.

What radiators look like is foil or sheet covering fluid loops to spread the heat, control the color, and add surface area.

In general, radiators are white because there's no reason for them to absorb visible light, and they're not hot enough to radiate visible light. You want them to be reflective in the visible spectrum (and strongly absorptive/emissive in the infrared).

A white surface pointing at the sun can be quite cool in LEO, < -40C.