The point around gravity is weak. We have exactly two datapoints for long-term human habitation: 0G and 1G. There is a vast spectrum between the two, the effects of which we simply do not know one way or the other; pretty presumptuous to assert any particular shape of that graph without even so much as a third data point. Can we get away with 0.5G? Can we get away with alternating periods of 0G and 1G? Lots of entirely-unanswered questions there. Hopefully, with new manned lunar missions on the horizon, we'll be able to collect more data on that front.
In any case, both centrifugal gravity and oxygen production are readily-solvable problems. We don't strictly need the artificial ecosystems in question to fully encompass what's on Earth to be suitable for long-term habitation; they just need to be sufficiently reliable.
"Can humans endure long-term living in deep space? The answer is a lukewarm maybe, according to a new theory describing the complexity of maintaining gravity and oxygen, obtaining water, developing agriculture and handling waste far from Earth."
Biosphere 2 (the most (in)famous example) did not end in "starvation and/or psychosis". It ended in external management squabbles over research objectives and funding that spilled into the in-isolation teams. The first of said teams reported a constant feeling of hunger during their run, which was the result of a deliberately-chosen minimalist diet and was resolved by the end of that run (and the next).
There were, in short, a lot of successes from both of Biosphere 2's runs, in spite of the numerous challenges - including farm yields multiple times as productive as typical Earth farms, in spite of the loss of pollinators. It was far from a perfect experiment, but it did resoundingly demonstrate that a closed ecosystem can be feasible, and provided plenty of lessons to be learned in achieving that goal.
I completely agree that Biosphere 2 was a great experiment. But at no time was Biosphere 2 a functioning independent biosphere -- it was a slowly decaying station. I think it is likely that we could eventually make one work. But that is a long way from "demonstrated feasible".
If you struggle to manage respiration, food is not your problem.
"The oxygen inside the facility, which began at 20.9%, fell at a steady pace and after 16 months was down to 14.5%."
"Daily fluctuation of carbon dioxide dynamics was typically 600 ppm because of the strong drawdown during sunlight hours by plant photosynthesis, followed by a similar rise during the nighttime when system respiration dominated. As expected, there was also a strong seasonal signature to CO2 levels, with wintertime levels as high as 4,000–4,500 ppm and summertime levels near 1,000 ppm."
> Since some biospherians were starting to have symptoms like sleep apnea and fatigue, Walford and the medical team decided to boost oxygen with injections in January and August 1993. The oxygen decline and minimal response of the crew indicated that changes in air pressure are what trigger human adaptation responses. These studies enhanced the biomedical research program.
> [...]
> The respiration rate was faster than the photosynthesis (possibly in part due to relatively low light penetration through the glazed structure and the fact that Biosphere 2 started with a small but rapidly increasing plant biomass) resulting in a slow decrease of oxygen. A mystery accompanied the oxygen decline: the corresponding increase in carbon dioxide did not appear. This concealed the underlying process until an investigation by Jeff Severinghaus and Wallace Broecker of Columbia University's Lamont–Doherty Earth Observatory using isotopic analysis showed that carbon dioxide was reacting with exposed concrete inside Biosphere 2 to form calcium carbonate in a process called carbonatation, thereby sequestering both carbon and oxygen.
> [...]
> After Biosphere 2's first mission, extensive research and system improvements were undertaken, including sealing concrete to prevent the uptake of carbon dioxide.
Long story short: it was primarily an issue with the concrete absorbing the carbon dioxide (which otherwise would've been converted back into oxygen), lowering overall air pressure. Said issue was fixed by the second mission.
It would certainly explain things, like why we seem to be out nowhere.. I mean there is no signs of life, against all the odds. Deep mission alright.
It would explain why we started agriculture, civilisation etc so suddenly. It would also explain many of the myths, such as the ones about star people visiting us.
I would obviously create and seed a planet first, then monitor its development upto a point before going in to live onsite. Maybe we had created some folks there to do some gardening. When you arrive and they're treating you like a king and after you left eventually the stories started to seem like fairytales.
It would fit with the idea that there was an ancient advanced ciliation, who was wiped out about 12,000 years ago, because of something like flood, solar events or asteroids caused floods etc. or they decided to reboot the experiment. But few who survived were able to restart civilisation at some basic level at least.
Since our ancestors were wiped out there has been this state of amnesia, like Graham Hancock puts it. We have been left wondering in the dark, asking ourselves who we are, why are we here and if there is anybody out there.
Maybe "the gods" will return some day and offer us way back home, but we will probably try to shoot them. All thanks to Hollywood brainwashing the world to imagine that aliens are some space insects who want to turn us into batteries. Why not imagine it would be more like the final episode of Battlestar Galactica or the world of Expanse? But who knows, maybe they're already here and some suspicious folks are freaking out.
Anyways, sorry about that. Just felt that this train of thought was supposed to be spilled out here. <InsetAllTheDisclaimersRequiredHere />
What are you apologizing for? Your reply is quite insightful and makes far more sense than quite a number of theories being bandied around by 'some' who call themselves scientists.
Thanks for saying that. I have just come to notice that this HN community can be ruthless and lacking sense of humour and imagination. Even with apologies I always get downvoted. I don't really care but it's a funny game :)
This is exactly what we should build AGI to do - explore places humans can’t.