I'd like to see some serious work on the other proposal for "living off the land" in interstellar space.<p>We know comets and other interstellar bodies contain a lot of hydrogen which has a higher deuterium content than hydrogen on Earth.<p>Designs such as ITER and stellerators should scale up with increasing size and it's plausible that D+D fusion could be developed on the existing path. In fact a very large "inertial confinement" fusion device was fired based on D+D<p><a href="https://en.wikipedia.org/wiki/Ivy_Mike" rel="nofollow">https://en.wikipedia.org/wiki/Ivy_Mike</a><p>and got a massive positive energy return.<p>D+D fusion produces He3 and T, both which are better-burning fuels than D+D. These can be burnt all the way up to He4 in one big reactor, but one can imagine a system that separates out some He3 and T to be burned in smaller secondary reactors. D + T fusion produces terrible neutron radiation but you can let the T sit and it decays with a 12-year half life to He3 and use the much cleaner D + He3 reaction in secondary reactors with favorable scaling, less shielding, no breeding system, etc.<p>Those travelers only need to get to the next comet so they don't need to be terribly fast, but the great advantage they have is a sustainable lifestyle even if they never arrive at another star -- those kinds of travelers might not find planetary systems interesting at all.