The picture I posted? It's a fusion plant being built. Not to check whether plasma can be achieved, but to scale up previous successful experiments to the level of power generation because it worked. It's engineering and amusingly, all scientific powers on Earth are on with it.
As a physicist, albeit not a plasma physicist, I am not nearly as sanguine as you are that ITER will successfully demonstrate the feasibility of fusion power stations, at least to the extent necessary for DEMO to go ahead. There are many previous cases of people thinking, "Ah, we've got it" only to discover that, no, they haven't got it. Even more cases of discovering that something that seemed feasible in engineering terms wasn't (and yes, this applies to space habitats as well). I'm also not at all sanguine that fusion will ever become a major power source, because it seems likely to me to have the really killer problem with fission--viz., massive upfront capital costs and inflexibly large plant sizes.
Nah, the big issue is that the cost of human space travel climbs much faster with distance than with machines. Going from the Earth to the Moon and back was a week-long mission that could be done in a cramped space. Mars or other places? It becomes years in which everything must go perfectly or you get a massive failure. And where the 'qualitative' complexity is already incredibly higher than with robots. Could human beings do hundreds times more research than modern rovers? Because we are likely to reach that ratio, possibly more if the failure risks need to get lower than rover missions.
Current cost estimates put a Mars mission at being roughly in the same bracket as Apollo or the ISS, actually, although usually that involves only a few flights. Even the hideously overbuilt 90-day report plan was "only" going to cost $500 billion and give us a lunar base, majorly expanded ISS, and so on and so forth in addition to Mars missions...anyway, the answer (given the known cost of rover missions and the estimated costs of human missions) is
absolutely yes. Compare, for instance, the distance traveled by Curiosity, which cost around 1% of what a human mission would cost: 20 kilometers, over a seven year period. Not terrible, especially for a robotic mission. Now compare to how far Apollo 17 astronauts traveled in their rover: 35 kilometers, 75% farther, and in just
three days. That kind of difference matters, because if you can travel quickly you can visit more sites or more easily revisit sites if and when it's determined that they're more interesting than you expected. And that's just one thing, not to mention all the other advantages that humans bring to the table in terms of flexibility and capability.
Again, if pure cost-effectiveness was the only consideration we would have launched human Mars missions in the 1980s, because they clearly return a lot more on what you put in than robot missions. But no one is willing to put in the admittedly substantial upfront cost, so there's a compromise on robotic missions as being the only thing that's actually feasible to do given allocated funding.
Wouldn't you rather turn the planet into a park than a prison? Wouldn't you rather have all the industry off the planet's surface? I would.
Maybe, but the question is whether people will pay for that. I don't think they will. They'll be happy enough if there are large parks and relatively minimal environmental impact from industry where they live, which doesn't require going into space.
Once you've got that, you've got the driver for more people & more habitats.
Not really. Look at oil platforms, which is more or less what we're talking about. There hasn't exactly been a concerted effort to colonize the sea despite all that.
And if you're launching from Earth's surface, it's insane. And if you only build one, it's going to be hideously expensive. What idiot does that? And where did I ever even hint at being so stupid?
Launching off Earth's surface nothing, this is the total integrated cost for putting one together. For comparison, a 787 costs about $300 million and masses about 130 tons empty, which translates into a cost of $200 000/ton, while the Burj Khalifa cost about $1.5 billion and masses about a million tons, or about $1 500 per ton. Even with a high degree of automation and granting that a large portion of the mass is, as I said, in the radiation shield, I would consider a cost of $100/ton to be
rather optimistic at best.