[tensor_rank_0]

they will be IR visible, but what do you mean they don't exist? Apollo used them to bleed off excess heat.

[pocketstar]

"A black body is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence." [0] Black bodies are theoretical, they do not exist. Apollo had radiators, they might have been black but they were not a black body. Vantablack comes close to a black body for the visible spectrum which is p cool tho.

[0]https://en.wikipedia.org/wiki/Black_body

[tensor_rank_0]

> Black bodies are theoretical, they do not exist. Apollo had radiators, they might have been black but they were not a black body.

they were, as I said, "black body radiators" which are not theoretically ideal black bodies, but still manage to radiate black body radiation.

[dannypgh]

I think the term you're looking for is simply "radiator."

[tensor_rank_0]

yes that is more parsimonious however in non-technical language the term "radiator" is associated with heat exchangers. if you put heat exchangers on the sides of your spacecraft they would function as radiators so I suppose it doesn't matter anyway, arguing semantics is a waste of time.

[pocketstar]

a "radiator" is a heat exchanger and "radiator" is the industry standard term. these semantics are required for effective communication about technical topics.