[AtlasBarfed]

Except that fusion on earth will likely never be cheaper than solar/wind.

I mean that is a cool scifi story, but economics seems to hate cool things.

There's this "big lie" that fusion people imply that it will be cheap, clean, and limitless.

Cheap is doubtful, clean is undermined by the reality that fast neutrons from fusion degrade the reactor to radioactive isotopes, and ok the fuel is pretty much limitless

Now, if we can get scalable fusion as viable load levelling, to develop it to the point it can be used in space then that's some real scifi.

[audunw]

I thought so too. It’s pretty simple: if you’re making a nuclear thermal power plant a lot of the costs are associated with building the containment vessel and the heat exchange mechanism. Fusion is fundamentally lower power density than fission, so you’ll need a bigger vessel for a given power, and both the containment and heat exchange mechanism are far more complex and expensive. Thermal fusion will never be cheaper than fission, which already has a hard time competing with renewables. And renewables are still getting cheaper.

But then there’s Helion. If you can extract electrical power directly rather than through heat exchange and a turbine, it changes the equation drastically. So I think their approach can work from a theoretical point of view.

[thechao]

Fusion will be necessary if we plan to colonize the solar system beyond Mars, and not at Jupiter. It's cold, dark, and scary, out there.

[tsimionescu]

We won't, not with anything resembling current technology. So, if we were to imagine a colonized solar system, there is a good chance it's not fusion that gets us there, but some currently unknown technology.

[AtlasBarfed]

Jeez, they invented the core tech in the 60s. An orion pulse nuclear ship can get a small city to Jupiter in a month.

You don't need a wonder technology to cart around the solar system, well, unless you are talking ECONOMICAL technology.

I'm not sure how expensive H-bombs are to make at scale.

[tsimionescu]

I'm not talking just about transportation, I'm also talking about the technology required to make an actually self-sustaining human colony anywhere outside the Earth. That is the part that only exists in principle - when you go to the details, we don't actually have any idea how we could build even a Mars colony that is truly self-sustaining, never mind one on a more inhospitable world.

Note that when I say self-sustaining, I don't just mean power, food, air, and water. I mean everything that a high-tech colony actually needs - plastics, machined parts, microprocessors, software, and so on.

[pfdietz]

Power can be beamed out to interstellar distances, so fusion isn't necessary.

For that matter, if a space colony is equipped with a mirror for concentrating the sunlight needed to illuminate the inside as if it were Earth, and we place the limiting distance as that at which the mass of the mirror is equal to the mass of the space colony, the distance is about 1 light year.