Peltiers are never an alternative to radiant cooling. They do not get rid of heat, they pump it from one side to another (if you apply power) or resist its flow

Peltiers are never an alternative to radiant cooling. They do not get rid of heat, they pump it from one side to another (if you apply power) or resist its flow (if you extract power -- this is what RTGs do). You still have to get rid of the heat when it reaches the other side of the Peltier.