Also, point of note: it's unlikely you'd actually grow plants and humans in interconnected habitats anyway. You might pump some gases from one to the next, but: agriculture takes up lots of area / volume. If you're talking Mars rather than Venus, then you're talking large pressure vessels, which is a lot of mass, proportional to the pressure differential. Which is expensive. But plants tolerate living at much lower pressures than humans (and there's potential to engineer / breed them to tolerate even lower - the main problems are that they mistake low pressure for drought, and that's a response we can manipulate). So it makes much more sense to grow them in large, low-pressure structures with a mostly-CO2 / some O2 / no N2 atmosphere, rather than at human-comfortable pressure levels.

That said, you don't want human workers having to work in pressure suits, so ideally you'd use a sliding tray system (we use them on Earth to save space in greenhouses) or similar, except that you'd move the plants through an airlock into a human-comfortable area for any non-mechanized work. Obviously, mechanized systems can operate at any pressure level, and also obviously, some work would still need to be done in pressure suits every now and again (maintenance, cleaning, etc).

None of this applies to a floating Venus habitat, where in your typical Landis design your crew - and potentially agriculture - are just living in your lifting envelope, at normal pressures. The envelope is massive, so you have no shortage of space for agriculture, all well-illuminated from all angles if the envelope is transparent. The challenges there are different - how to support them, humidity management, water supply, falling debris, etc.

It's unsurprising; but I see that the law has several stages of dealing with foreign overcrowding if the 10 million line is breached; but nothing about how locally produced human resources will be stack ranged for headcount reduction should the population remain above the target. Surely anyone who really cares about crowding needs to have a contingency plan for endogenous losers as well?

If only the US had some sort of aid program designed to try to make conditions more favourable in the sort of countries that economic migrants tend to flee from. Maybe the US could call it "US Aid" or something, and give it a decent budget rather than gutting it to save $23 per American.

But the main issue is that the proper solution is obviously to have a formal, controlled, actually viable work visa system for economic migrants, distinct from asylum. The US economy is immensely boosted by millions of (generally awful) jobs being done by illegal immigrants at substandard wages (which are still vastly more than they could get at home), making US goods far more competitive than they would otherwise be and pumping huge sums of money into the economy. Formalize it. Basic worker protections but not the minimum wages or benefits that citizens get. You drop off an application for a sponsoring company, and so long as you're employed with them and not causing problems, you can stay. Fired, laid off, or quit, and you go back to your country (where you can reapply for a different job). You can also promote maquiladoras, wherein immigrants are also working for your companies, but the labour is being done across the border (but the goods move freely without tariffs, so it's like having the work done in your country).

(I find it hilarious hearing people like Vance talking about how he'll bring housing costs down by kicking out immigrants, freeing up housing. Um, dude, exactly who do you think it is that builds the housing in much of the US?)

"Refugee papers" OMG I'm dying here...

Biosphere 2 was an attempt at fully closed loop self-regulation. That doesn't work, and is not what is under discussion. The discussion is of using systems to maintain environments.

Production of oxygen is not remotely difficult. Not by plants, but again, industrial systems. Systems to make O2 from CO2 and/or water are TRL10. They exist, you can just buy them off the shelf. Same with reusable CO2 scrubbers (it's a very simple chemical process: cool = absorb CO2, hot = release CO2; they just cycle between cold and hot and whether they're connected to the input or output)..

You seem to have the idea that the proposal is just to have plants and humans life in harmony with no technology. If that were the actual proposal, I would agree with you. But that's not the actual proposal.

Yeah. Because if Mars' gravity is insufficient, and you'd have to live in rotating habitats anyways, then what are you even doing there, instead of being located e.g. on an asteroid where it's much easier to make a rotating habitat, where your surface is much more resource-rich, and where delivery and return of goods is much easier?

Venus, by contrast, I think few people doubt that its gravity would be sufficient for human life. Mars, it's *probably* enough, but it's not well studied. Moon seems like a coin toss at this point.

It's not entirely clear, but it's quite possible, arguably probable, that at least part of Venus's highlands involve fragments of ancient crust (the highlands also have milder conditions for exploration). Venus was Earthlike before Earth was, with vast warm oceans. There's also some arguments for life in the atmosphere based on gases that have been found, although I don't buy them (in the same way that I don't buy the same arguments for current surface life on Mars).

At least in the current climate (and quite possibly indefinitely; depending on how prudent their investments are and whether they have any uncontrollably expensive hobby) there's not really any reason for the 'AI' guys to take such a servile attitude.

If you actually need the job, or are invested in the company's mission for some reason, it's a good idea to care at least slightly about how your paycheck doesn't bounce; but that's not really the position these guys are in. Exceptionally in-demand skillset and reputation; existing net worth almost certainly already enough to at least keep them comfortable indefinitely if they feel like quitting the rat race or get fired. Why settle for doing sordid adtech if you think that, best case, your boss in the sort of dumbass who would lose billions of dollars on the idea that Second Life would totally have the GDP of western europe, because reasons, and you can keep him paying you a handsome salary and providing you with the GPU compute time and dubiously sourced datasets that you find personally interesting; and worst case, if you lose the fight, you'll just be told to go sling ads, not fired and blacklisted.

Facebook isn't running a charity; but neither are these guys. Why wouldn't they try to take what they can get? Especially when the actually-profitable business units are fat enough that there's plenty of room for boondoggles, so long as you can sell them, rather than there being fairly tight constraints on how much you can waste before the company starts bleeding out.

It would honestly be more surprising if they signed up with facebook out of a genuine willingness to do adtech swill and sordid 'engagement' hacking; rather than on the assumption that there's enough desperate dumb money sloshing around in Zuckerberg's fear of missing out on the next big thing that they can get paid to pursue their pet projects without much concern for having to deliver short term impact on the bottom line.

I assume that at least some of the tension here is that facebook hired these guys to be the hotshot golden boys of sucking less at AI; so it isn't just an it's-only-money thing. I don't know whether or not this belief is accurate; but Zuck and friends certainly hunted down and paid for the various new AI hires as though they were capable of things that in-house or more readily available alternatives are not, so the battle over where their attention will be focused is presumably being waged on the assumption that having someone else do what they aren't doing isn't really a substitute.

What I would be curious to know is why the 'build god-machine' goal isn't being treated as the obvious winner just because you can have the god machine make facebook more addictive and better at serving ads. Do they think that the AI guys are drinking the kool-aide and the only thing they'll actually be able to deliver is incremental improvements; so they want those churned directly into products? Some degree of confidence that they will eventually manage it; but fear of missing out on some sort of short term advantage means that they don't care about what is achievable in 5-10 years? Genuinely zero interest in anything except making social media more of a hellscape; so they simply don't care?

I suspect that, while it would be socially controversial, planetary colonization would be a very strong case for IVF and some population planning.

For the amount of volume/mass required to ship a single human and support them in transit and on site you could ship a lot of embryos in cryo(it's careful plumbing; but a big dewar flask kept at cryogenic temperatures is downright lightweight compared to a full life support system); and shipping embryos gives you the option of bringing massive genetic diversity, thousands to tens of thousands of genetically screened parents worth of embryos in the space a single person would require.

Unless you've got some sort of advanced growth vats you would obviously need people onsite; but instead of dealing with the probably-impossible task of keeping a tiny breeding population's gene pool in order you'd just be defrosting and gestating specimens from a much larger pool of diverse embryos as needed. Presumably you'd initially go with an all-female colony, and only start defrosting males and trying to maintain a viable natural population once you had at least high single-digit thousands to low-mid tens of thousands.

I'm sure that such an arrangement would freak some people out; and you'd probably need to do some reasonably intense social engineering to keep everyone on-mission; but in terms of efficiency of genetic diversity there's a fairly compelling case to be made.

What sort of disaster do you have in mind that would render earth less habitable than mars?

Short of unstoppable replicator nanites turning the entire crust into grey goo; or very long term issues with the sun reaching EoL that will be an issue for basically anyone in the solar system, it's honestly hard to think of ways you could break it more badly.

Plenty of possibilities that will make people deeply miserable; or cause 80+ percent of the population to die horribly; but you'll still have a planet with the right gravity, an atmosphere and magnetosphere, some sort of ecosystem(even if it's just algal scum and cockroaches); some soil that isn't riddled with perchlorates, and so on.

That's IMHO really overplaying it. I don't want to downplay food production effort difficulty, but saying "because we've never done it we can't" is like saying "Because we've never built a 5-meter-tall statue of a puffin made of glued-together Elvis dolls, we can't". We absolutely can, it's just a question of whether one thinks the investment is worth it. And I'm not talking out my arse, I have a degree in horticulture with a specialty in greenhouse cultivation. So much of the "keep the plants alive" systems we already do on Earth - you just need to get them there in an affordable manner.

The primary consumables are water and fertilizer. Nobody seriously is proposing building a colony that can't produce its own water. As for fertilizer, that would start off as an import, but a much smaller import than the food mass. On Earth, open-loop fert systems are fairly common, but they're slowly losing ground to closed-loop where you just maintain the EC, filter the returning solution, and every now and then due a nutrient-level test on the solution and individually adjust whatever nutrient might be lacking vs. the others.

We can consume lots of growing medium, like disposable rock wool cubes and the like, but we can also not do that. For example, it's perfectly fine to grow plants in clean sand / fine gravel - just clean it and sterilize it between uses. Something like pumice is better, though it slowly breaks down between uses. But you don't have to use anything special.

If you do LED lights, you may get a decade or so out of them. You can reduce shipping mass for replacement by going with designs that let you replace just the light boards from them (Mechatronix has lights like this for example), no need to resend e.g. the heavy heat sink, etc.

There's a million random things you use or that can wear out, from cleaning solutions to solution pumps to climate computers and and on and on. But they're not a meaningful import-mass, at least compared to food. Really, the big thing is fert. But regenerating fertilizer from waste (plant waste, human waste) should not be - industrially - immensely complicated. For the metals, burn to oxides / hydroxides, dissolve in acid, fractionally crystallize. You'll always lose some from the system, but we're not talking large amounts. For nitrates, Haber-Bosch is nothing exotic to adapt, and you have easy feedstocks (mining is complex, sucking in gases isn't).

(To elaborate about PELs: Venus's middle cloud layer is ~1-10mg/m3, depending on altitude, latitude, and what study you trust (our existing data isn't great). OSHA PELs are 1mg/m3 for an 8-hour shift. NIOSH's RELs are also 1mg/m3 for a 10-hour shift, with IDLH of 15mg/m3. Now, this has the two aforementioned caveats. On the downside, Venus's aerosols are higher molarity - 75-85% concentrated vs. ~20% on Earth. On the upside, the vast majority of the PEL/REL/IDLH risk is from inhalation, which obviously, you can't be doing in any atmosphere in our solar system other than Earth. Dermatitis thresholds are far higher. So again, so long as there's not rain/snow/dew/frosts, and you're at the right altitude/latitude combination**, you could probably spend some time outside in shirtsleeves and a facemask, and feel an alien breeze against your skin.

** One also has to stress latitude, not just altitude, as it's cooler for a given altitude as you get closer to the poles. While Venus's middle cloud layer climate is "similar" to Earth's, it's a bit on the warmer side for a given pressure than Earth's - and because an aerostat rides "down" in the atmosphere vs. its internal pressure, esp. at night when it's no longer being heated by the sun, it amplifies the impact. So if you're going to be living in the envelope, you need to find the right balance between how far you want to go below 1atm and how hot you want to have it be outside. Shifting more poleward helps find a better balance between the two (at the cost of lower sunlight availability for solar power vs. the super-bright equatorial regions). It also shortens your effective day (faster superrotation period). You probably don't want to go fully to the poles, though, because of the polar vortices (though how turbulent they are is still an open question).

BS. There's no ozone and at the height these balloons would float the UV and assorted stuff from the sun would fry you in seconds.

They are, however, correct. Venus has no (innate) magnetic field, only a weak induced one (about 2x that of Mars's induced field), but it has a massive atmosphere. The mass of matter over your head at a reasonable habitat altitude/latitude combination is equivalent to that of about 5 meters of water. Way more shielding than is necessary for human life. Of course, having even more shielding would be even better, as it would of course be nice to have Earthlike protection levels. But you could survive even a Carrington Event on Venus. Getting 5 meters of water-mass-equivalent over a Mars habitat, while doable, is quite an undertaking, and means you're living basically in a bunker.

Wtf re you smoking? Archimedes principle holds on Venus just as on Earth. Lose your lifting gas and you sink and on Venus you'll soon start to cook.

Aerostat internal pressures are very similar to the pressure outside of them, and they hold a tremendous amount of gas. A 1 cm hole is basically irrelevant in an aerostat; it's just some extra work for your gas generators, vs. what it already has to overcome due to gas diffusion through the envelope. By contrast, a 1cm hole in a tin-can habitat on Mars will kill you in minutes.