>>11640826big fuckoff radiators
It's one of the interesting challenges of space travel, and eventually, space warfare; the ISS has no engine, no reactor, no weapons and a teeny little crew, but it still requires a lot of radiator surface area to keep it cool
Warships would require much, much larger radiator arrays, and of course, those are going to be the first thing you shoot for because once they're gone the enemy is, at least, not going to be able to fire anymore, or at worst is going to have to shut down his engines and reactor to avoid cooking alive in his own hull
You could use retractable radiators, of course, but then there is going to be a finite number of laser shots or whatever you can take before you get too hot, or a finite amount of manuevering, and they're both drawing from the same limited resource, your heat capacity. Do you shoot three times and maneuver twice? Shoot twice and maneuver three times? Better not get it wrong!
Will be interesting to see (for whoever is around when this stuff kicks off) how they address these problems. I suspect missiles are going to be the weapon of choice, since they carry most of their heat problems away with them, unlike a laser or a rail gun or whatever.