[stevenhuang]

Solvable with a large enough thermal mass. And once we're able to start mining the moon or asteroids for mass to be cheap enough, heat would no longer be a problem in space: use conduction and convection to move heat away quickly, have a holding area for hot matter for radiative cooling to do its thing, then keep adding additional mass until equilibrium temperature of the system is below requirements

[mlyle]

Thermal mass doesn't change the equilibrium temperature at all. Only increasing surface area does (well, and changing its emissivity) .

[stevenhuang]

> have a holding area for hot matter for radiative cooling to do its thing

The implication of course is that surface area can be increased trivially by adding matter. And with a larger thermal mass, more energy will be required to heat the system to the same temperature, giving more slack in the system for radiative cooling to work.