The Confederate eighty-footer, mainstay of Space Fleet, needs to be able to get far enough from the gravity well of a planet to be able to engage the Orthodynamic (faster than light) drive. That means it needs some serious engine power.
Chemical propellants won’t do the necessary. The Space Shuttle needed solid rocket boosters and a huge external fuel tank. There’s no time to fiddle about with that sort of stuff when you need to rush to the rescue or chase after the bad guys.
What Jane needs is something that will fire up pretty quickly when she turns on the master switches, and that will keep everything contained within the hull.
There’s only one process in nature that will do the business, and that’s nuclear fusion.
I do mean fusion. Conventional nuclear power uses fission. The great advantage to fission is that it’s very easy to start. If you get a critical mass of any fissile material in one place, the chain reaction just lights up of its own accord. The problem is stopping it before you have a melted reactor and at best a puddle of horribly radioactive gunk, at worst a mushroom cloud.
Fusion is much more house-trained. The quantities of fuel involved are far smaller, and the radioactive waste decays away in a couple of days. More importantly the reaction is, from the engineering point of view, exceedingly difficult to get to run at all. If anything breaks the flame just goes out.
Or as Jane explains it, “There are some things I shouldn’t tell you and some things that would take too long to explain. If I say that wherever I go I leave a little more helium and a fraction less hydrogen behind-“
So that’s how it works. Of course there are a few problems involved in getting a notoriously slow reaction to run fast enough, and in containing the fusion plasma at about ten million degrees Kelvin.
That’s just engineering-