An orbital datacenter's sustained heat rejection is constrained by its radiating area, emissivity, radiator temperature, and radiative environment.

groundsnasa-small-spacecraft-technology-thermal-control.md

Qout,rad (heat emitted via radiation) includes the surface area designated as radiator space, the IR emissivity of the surface, and the difference in temperature between the spacecraft radiator and the heat sink to which it is dissipating, typically and most effectively deep space.