There is some medium in low Earth orbit. Not all vacuums are created equal. However, LEO vacuum is still very, very sparse compared to the air and water we use

There is some medium in low Earth orbit. Not all vacuums are created equal. However, LEO vacuum is still very, very sparse compared to the air and water we use for cooling systems. The main way that heat dissipates from space stations and satellites is through thermal radiation: https://en.wikipedia.org/wiki/Thermal_radiation https://en.wikipedia.org/wiki/Thermal_radiation.