Futurology

It does, which makes this part curious:

But these new thrusters are capable of being powered by any metal that can burn, such as iron, aluminum or copper,” Dr. Kim explained.

Maybe they're using an initial chemical burn to get the propellant in plasma form? Or maybe it has something to do with avoiding buildup on internal surfaces?

Don't forget the moon! It's a perfect location to build a lot of spacecraft, being right there but also most of the way out of our gravity well. It doesn't have much in the way of volatiles, unfortunately, but it has plenty of metals.