Cooling in a vacuum is a lot more difficult than with an almost endless supply of cooler gas to run over your hardware. The ISS runs liquid ammonia cooling to l

Cooling in a vacuum is a lot more difficult than with an almost endless supply of cooler gas to run over your hardware. The ISS runs liquid ammonia cooling to large sets of radiators in order to keep the station and solar panels cool. I'd imagine you'd need a similar setup if you're putting your cubesats far enough out that they won't need active propulsion to stay in orbit, and if you're using similar consumer hardware.