Coolant [Spaceships]

[Agemegos]

Originally Posted by ericbsmith

I'm presuming they use Tungsten because it has 3x the density of Iron. This allows it to have a smaller cross section and carry more kinetic energy to the ground. I presume they would have some sort of protective coating, and maybe an ablative end cap for reentry; that combined with the long thin reentry profile, the idea is to not have them slow down too much in the atmosphere and thus not heat up enough to melt.

Tungsten also has a very high tensile strength and the highest melting point of any metal, and the lowest vapour pressure at high temperatures. It has a lower specific heat capacity than iron but melts 1838 K hotter with four times the specific heat of fusion. It is tough, cohesive, and more refractory than anything else but graphite. Tungsten is strong enough to withstand a very high ram pressure, dense enough to pack a hell of a lot of momentum behind a given ram force, and better than anything else except for graphite for withstanding high temperature.

But anyway, the impracticality of Project Thor is admitted but not important, and spaceships are unlikely to be built out of tungsten. The point was that any spaceship in or capable of reaching low orbit is weapons-grade. It's the very least and most inescapable demonstration of Jon's Law: "any interesting space drive is a weapon of mass destruction".