[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.