[tullianus]

Tried to use one of these in a space application once: cold side on the sensor, hot side attached directly to a radiator. Unfortunately the thermal conductance [W/°C] from the hot side back to the cold side was high enough (relative to my radiator's thermal conductance to space) that I needed to pump not only the sensor's heat load, but a small fraction of the Peltier's heat as well, which ballooned the electrical power required. Not worth spending that much power to buy an increase in SNR from a cooler sensor.

[nerpderp82]

Many CCD cameras used for astronomy use a TEC stack to cool the sensor. Separating the cold and the hot side is paramount. Haven't used it in space, but I'd probably use a vapor phase heat pipe to move the heat as far away as possible before radiating the rest of the heat away.

[tullianus]

That would have helped a lot! Using a high-conductance device to transport heat away from the hot side before switching to lower-conductance devices for heat rejection. All I can say is that my thermal philosophy wasn't as robust back then, and I also had an irrational fear of heatpipes :)