The problem with using mirrors as radiators is that they're terrible radiators. They might be great at reflecting the sky-photons away, but they won't launch their own photons away either.
Shiny things are great at reflecting incident radiation (which is why they're good mirrors) but bad at radiating their own heat. Dull black things are bad at reflecting but good at radiating. The technical terms are reflectance, absorptance, and emissivity.
Shiny things are great at reflecting incident radiation (which is why they're good mirrors) but bad at radiating their own heat. Dull black things are bad at reflecting but good at radiating. The technical terms are reflectance, absorptance, and emissivity.
http://www.optotherm.com/emiss-physics.htm