Just how practical would fission fragment rockets be in the distant future for reaching 550AU or greater distances in human lifetimes? Would fission fragment reactors ever be a practical source of energy generation on land?
I don’t know; what’s a fission fragment rocket?
Frrankly, I’m not sure myself.
I feel like a power reactor that spews out fission fragments as a matter of its design would be a non-starter. We’ve got lots of new possible reactors that would be far safer, so that even if they were less efficient, we’d still prefer them.
How do you feel about it as a form space propulsion?
Using a nuclear reaction to heat something up and spew it out the back is a reasonable near-future technology idea. But there’s no reason why the stuff you spew out should be the spent fuel itself. In fact, it’s a fairly bad choice. The efficiency of a rocket depends on the speed of the exhaust. The temperature of a substance is, basically, the amount of energy per particle. So for any given temperature, heavier particles will be moving slower than lighter particles. Fission byproducts tend to be fairly heavy, as atoms go, so they’ll be going slower than, say, hydrogen. So it’d make more sense to use the fission reaction to heat up hydrogen, and spew it out the back.
And for a power-generation reactor, you probably don’t want to be spewing anything. We can already make fission reactors that work just fine for power generation. The only problem with them is that people are irrationally scared of nuclear reactors, and that would apply at least as much to a fission-fragment reactor.
Yes, but they’re claiming a specific impluse (Isp) that’s really high. That’s a measure that takes into consideration all those factors. I guess the real question is how long they can maintain that, as compared to other nuclear engines. The science seems sound, but as usual, the engineering might screw us.
Are you by chance thinking about putting a space telescope out that far and using the Sun for gravitational lensing?