Which is why we start thinking now. Scale is a bugaboo of terrestrial manufacturing - in free fall, it's mostly a problem of containment and "tidal" forces (large structures would have different bits moving at different speeds in orbit, a problem which can be utilized for stabilization, but causes problems with stress, at the very least). Spinning the terrarium can be done with mass drivers (railguns that recycle the cartridge that launches the ballistic pellets), but then there is access issues after spinup, which is done at holes at the poles - but I have a neat idea about that. Big issue is harmonics - something that is hard to compensate for. The damn things would ring like giant bells, constantly. You really don't want pulses or waves to harmonically reinforce, for instance. Most habitats are assumed to be cabled in the interior like an Escheresque suspension bridge in which all land is anchored to to the other land. Does it have to be so? Probably, but its been forty years - any new ideas?

The notion I'm putting forth here, and now will put up to the National Space Society for yak-yak, is that perhaps it might be far easier than we thought to build large structures, if we get away from the drydock-and-rivets methods we assumed would be used.

Assume a habitat of about, oh, a thousand feet in diameter, a Bernal Sphere, named after the guy who thought up the shape (O'Neill names the cylinders). You assume lunar material is melted by mirrors in free fall, then somehow separated into elements or compounds, then piped into molds or sheets, then cut, moved, and welded into a hollow sphere over a period of months. We've been building giant structures on earth for centuries; size is not a problem, effort is. The idea is to get rid of effort/money/time as much as possible. The whole thing has to be covered with radiation shielding, which was assumed to be slag or just lunar soil packed around the sphere like insulation. Some proposed magnetic shields, which make my eyes bug out - I would not like that to fail. Computers and machines should be minimized in design - failure points. The whole thing is spun up and then filled with air, then landscaped and filled with whatever. People, certainly. Trees, dogs, cats, itty bitty creeks, river around the internal equator, the usual. Water, BTW, HUGE issue. Hard to come by. The lighter elements are not present on the moon. Comets yes, Europa sure, carbonaceous condrite asteroids, yep. But those are solvable - we can rendevous with one of the close by asteroids and get some, eventually.

But the behemoth terrarium could be built faster, more easily, and perhaps better if we didn't do it WW I style. Picture two anchor shacks, shaped like dinner plates, facing each other. A compression tower/strut runs between those. Run flexible titanium cable or composite shield/metal cable out in a cylindrical pattern on the circumferences of those plates between the two shacks. Think of the two plates running thousands of cables between themselves, effectively making a cylinder. Then spin them. The cables gain angular momentum, and the cylindrical cats cradle bow open into a sphere as the cable is played out. Perhaps then latitudinal threads can be shuttled into the cables to make a mesh, or that could be done before and during. Then what? plating? or perhaps a flexible metal/ceramic cloth first, which is then covered with a vapor-deposited titanium layer, then feet of lunar soil to create shielding, then another layer of metal, and then done.... the G force caused by spinning stabilizes the entire construct during the entire process.

Or a balloon of titanium cloth is woven into a spherical bag, then inflated, spun up, then filled with lunar soil from the axis like a powder rain (radiation shielding), then all that is sealed up with another sprayed on layer (can't breath lunar soil accidentally - needs to be sealed), then terraform the interior.

The idea is to automate and simplify the big stuff. Also makes it a hella cheaper than hundreds or thousands of people welding plates together in a pressurized shack.

Or something more awesome, as I said, like blowing the damned thing up like a glassblower makes a goblet.

Any ideas?

Fusion creates felectrical energy by boing water into steam and driving turbines, which is bad for the wildlife in the water, for one thing. Second, inelegant, like creating a nuclear engine and using it to propel a horse on steam-powered roller skates. Best way to generate power is solid state, like solar or energy differentials in the ground. And, really, fusion ain't happening anytime soon. We need juice now. But to your point, he's not saying that we don't have the tech, which as he clearly outlined in his trilogy, we do, he's saying that the joint is poisoned, which is a bit more of a problem.

How is it that a science forum has people on it that think SF is silly?

Kim Stanley Robinson's Red Mars book. Read it, have your mind blown.

We won't drop that Mars stick easily. But it's a lousy place to live.

We can build millions of times more surface area in free space in rotating habitats everywhere but on gravity-bound terran-analog planets. There are more asteroids and comets than we can use up for centuries - and we just discovered a pool of water on Europa (yesterday I think) bigger than all the Earth's oceans and seas combined, which we can either railgun or pipe out into construction sites everywhere. We've got GREAT building materials waiting for us out there. And a hell of a lot easier than trying to make Mars habitable in a few hundred our thousand years. Mars will be a privately owned park/state/suburb/science station for sure, but it won't be the Big Hope for the human race, nor for the millions of other species we can save by either leaving in large numbers (meh, not for a long time) or transporting them into free space terraria where hard-nosed capitalists can't shoot, drown, poison, or eat them.

Now, with 3D printing tech and maybe some cool new ideas, we can do better than O'Neill and the others in building terraria. Giant blown steel bubbles? Spray metal and ceramic shielding over inflatable molds or gas jets? Magnetic molds? Oragami-like unfolded sections? Molten metal spun into shape like cotton candy? Spun metalic filaments, or ceramic/metal composite filaments 3D printed in place by crawlers or articulated arms on giant scale? Let's shake some dust here - any ideas? I'm serious - we've better tech and construction techniques than we had in the 70's. Building a giant aluminum/titanium bubble or cylinder with ceramic shielding should not be a problem in zero gravity. In the olden days, we pictured guys in construction shacks building it in pieces like the Enterprise in drydock. What can we do now?

So, we can inject a brain and then play games with it magnetically. I'm sure no one will use it to punish people, alter their behavior at will, or to try to change rebellious people into get-along types. Oh, oh, yes - or to try to quiet their kids down to get better grades and do more homework. After all, we nail them with chemicals to do those very things. No one will try to take a solid-state shortcut. 'Cause we don't trust tech that much, do we? No siree. We don't have blind faith in our programming skill and computer use, which is what is required to pull this off.

But it is going there. Nothing can stop it. Ways will be found. Give it ten years. First industrial scale, then expensive professional machines, then someone cracks the manufacturing code, as it were, and we're off to the make-your-own-cocaine-and-rogaine races.

It will happen, and soon. The journalist understands this. So, it is a printer. You are persnickity to the point of blocking the realization - chemical printers will happen, and it is part and parcel of the 3D printing flaming freakout that will shortly commence. They will have to shut this down HARD, to keep us from manufacturing pharmaceuticals and recreational drugs wihout the permission of IP "owners" or our frankly insane drug law enforcers.

Finding comments from even a few years ago is likewise so 20th century.

This is the beginning, of course.
Imagine the fainting freakout when they realize that we (if we were allowed to have a printer) make any drug we like. Or explosive. Or ammunition. Or laser components.
Don't bother imagining what the world's imaginary property "owners" will immediately demand - and receive - in the way of DRM and strict drone-and-goon raids on anyone who dares make an object they "own".
And further imagine the flaming worldwide war against printers when they realize we will be able to make electronic and photonic computers and comm systems that don't have their cute back doors built in from the factory or installed at the intercept point they use to infiltrate routers and other computing devices.
Phones: tracked. Computers: pwned. Unauthorized software and video/audio recordings will shortly become drone-and-goon felonies on every corner of the planet, as soon as Obama fast tracks the treaty. How about a raise of hands for those of you who understand that owning a chemical printer, much less an product printer, without real-time monitoring by entities outside our control will be likewise a drone-and-goon felony.

That is exactly what a Luddite was. Someone who wanted a piece of the new wealth as his job was taken from him to make others wealthy. Especially when that "someone" is most of the population and the "others" are a fraction of one percent of that population.

If you lost your job and were not a Luddite, you're either inheriting a piece of your forebearers' wealth created in boom times, or you're suicidal.

A Luddite was a worker in Victorian England who saw his livelihood and life being destroyed by industrialists who themselves became so wealthy the entire era became eventually known as the Guilded Age, as in gold.

Luddites didn't want to stop history, nor did they hate technology, or its benefits. What they WANTED was a piece of the pie that was taken from them - they wanted some relief from the horror that awaited anyone in England/Ireland/Scotland/Wales who no longer had an income. They were right; the era was a grinding hell for those whose centuries-old existence was eradicated by the industrialists. Charles Dickens was on the ground fighting for those people, for one; he immortalized their suffering and death in his stories, as well as agitating for their care.

The only relief for those whose lives were destroyed was death, eventually. London became a crowded hell for those fleeing the countryside. Crime went up, pollution was a horror (clouds of it causing mass deaths in the city on occasion).

What stopped it? The very thing that destroyed agrarian existence, industry, created the capability of much more active destruction - world war. Part one and two, really the same damned war, fought over foreign resources to fuel home economies. That war caused enough hell that the people actually fought for, and got, tax-funded relief from job destruction and industrial changes. Of course, they're reversing all that now - and it's working out very well for a tiny number of people. The rest are kinda going back to the way it useta be...

Sorry about the dupe. Pasted too much below the break, didn't see it.

Hm, indeed. But Mars will be a consumer of resources as far as the Earth is concerned, as it will not return energy or materials to the home world. It provides adventure and a limited amount of room for the fortunate; it can't ship back things we need, AKA power from powersats, or metals, or even habitats for animals that will be wiped out soon enough. As a side note, it would also consume our best and brightest, so the net effect for Earth would be negative again. Yep, we can do both - but Elon Musk is a Mars-only guy. And he doesn't understand electromagnetic launching from Earth, as he thinks we have to fire the ship through atmosphere at escape velocity right from the railhead, when instead you only require a few hundred miles an hour to eliminate the first stage. He is great, but he needs a little advice.

Given another option - leaving - human behavior changes. The Americas performed that function for Europe once, and now we need new Americas. Some will fight for the same old reasons - property owners, mostly - but the usual crew of poor and crazy and criminal will leap at the chance to start over. And the people in the sky will quickly outnumber the people on Earth.

The idea isn't to move people off-planet to ease population crowding, anyway. We can't ship enough - they are born faster than that. The need is to move industry and power generation off planet (and to provide a new place to live too!) so that enormous new energy and material wealth can shower down on the beleaguered overpopulated world. That gives us breathing room to bring living standards and education up to a level people limit their childbearing voluntarily. It happened in Mexico - their birth rate dropped to replacement levels when a certain level of prosperity and education was achieved. We need to do this to leverage our abilities to save our own asses down here.