[eesmith]

I believe pfdietz's point is there's no need to go to the Moon (or Jupiter?!) to extract 3He when sufficient 3He can be generated on Earth, at lower cost, and be energy positive.

Your digression seems irrelevant to that point.

We didn't use Heinlein stories as a source of evidence about reality. We didn't use thorium rockets to get to the Moon. Nor did we develop monoatomic hydrogen ("Single-H") fuel.

Similarly, we don't use Gundam stories.

Also, Project Daedalus' proposal to mine the Jupiter atmosphere for 3He for fusion predates the first Gundam episode, and is likely what influenced the series. https://en.wikipedia.org/wiki/Project_Daedalus .

[pfdietz]

If we're going to mine someplace in the solar system for 3He, I'd like to see it done on a (currently hypothetical) "Planet X", a Mars to Earth sized planet 100+ AU from the Sun. It could be cold enough out there for a bit of helium to remain bound over the life of the solar system, but it would be much easier to take off from again than, say, Uranus. And presumably with D3He fusion one could get out there with a fusion rocket.