Metal-fueled rockets are one type of the ion engine. Or they use the same method to create thrust as ion engines. The metal rocket uses metal vapor that the magnets drive backward. In space or inside the asteroid belt the system can get its energy from large solar panels. And outside the asteroid belt, the miniature nuclear reactor can give electricity to that system. In that kind of system, the long solar panels can also be used as a cooling system for the nuclear reactor. The metal engine can also use another material that it vaporizes. The metal engine can use magnetic metals as neutral atoms, which it drives through the acceleration track. But it can use ions and also things like water or hydrocarbons. In the last cases, the system ionizes material that travels through its acceleration track. Or it just raises the material temperature to make it expand. In those systems, the electric arc or some other electromagnetic radiation replaces combustion and causes the expansion of the fue