Feasibility study of a mission to Sedna – Nuclear propulsion and solar sailing

This direct fusion drive is a really interesting concept. Maybe something like this could be used for interstellar travel in a century (or five), it is very encouraging that there is active research on it. ~5kg of thrust is not a lot, but over time...

This sounds significantly more feasible than nuclear pulse propulsion ("project orion" style) which I used to think was the only feasible approach to get to another star.

One thing that was unclear from the paper to me: How does the fusion drive "pick" D/He3 fusion over D/D? Can this be "forced" by just cranking the plasma temperature way up? Or do you still just have to deal with a bunch of neutrons from undesired D/D fusion?

Roundtrip Interstellar Travel Using Laser-Pushed Lightsails

https://ia800108.us.archive.org/view_archive.php?archive=/24...

This is very interesting. Apparently beam collimation is much less of a show-stopper than I would have assumed.

But I don't see us putting a a 1000 kilometer lens into orbit anytime soon, and that multi-terawatt (sustained!) laser system sounds like a bit of a headache, too...