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DoktoroKiu t1_j8gyd0h wrote

Reply to comment by SoylentRox in Would an arcology be conceivably possible? by peregrinkm

The things you point to are still dependent on the Earth's biosphere. If you want a truly isolated system with no inputs other than sunlight you are screwed if anything becomes too unbalanced. The systems are complex enough that we cannot yet engineer them to be stable the way the Earth is, despite many decades of trying.

I do think that if it became important enough we might put enough resources into this problem to find a way, but as far as we know it may require a much larger biosphere to achieve it than would be practical.

And all of this is assuming you have fully self-sufficient manufacturing capabilities for everything you need to maintain these systems, which is itself a complex problem, especially regarding microelectronic components or other high-technology tools. They don't last forever, so even if you did figure out the biosphere problem your work is not finished.

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SoylentRox t1_j8gypbq wrote

As long as you have some minimum number of people (specialized skills) and enough manufacturing machinery, this won't happen.

I agree there are scenarios where humans might die, but I just don't feel you are arguing in good faith. "despite many decades of trying". What are you talking about? There was biosphere 2. And..........................

What else? Literally when has this ever been tried? The ISS is far too small to attempt a closed loop life support system. So I know of 0 examples other than a small cult effort that hit problems because I recall they had CO2 releasing from the concrete pad the biosphere was built on, no automation (subsidence farming is very labor intensive), no genetically engineered crops to help (hadn't been invented yet)...

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DoktoroKiu t1_j8nbh8z wrote

>As long as you have some minimum number of people (specialized skills) and enough manufacturing machinery, this won't happen.

You'd need quite a large number of people with many specialties, I think. The idea of a small self-contained system is more of the problem. You also can't forget about materials (how are you getting them?). Much of our technology relies heavily on the global economy, and there has been no effort put in to try to make these self-contained systems even on a nation-sized basis (except maybe North Korea, and even they rely on the global economy despite every desire not to).

We don't necessarily have a good reason to believe we can for sure make a smaller self-contained system. It may be possible, but it isn't a given, an. it's certainly not an easy problem.

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SoylentRox t1_j8nzxgj wrote

We're not talking about self contained per say. We are saying "if the earth is no longer inhabitable" but we still have access to it, so we can send people out in space suits or robots and get water, air, and minerals that have to be decontaminated and then can be used.

Every human not in your hab is now dead.

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DoktoroKiu t1_j8znbsv wrote

Odds are in such a scenario you starve to death when your mini biome has some minor issue that disturbs the balance and ends up killing some crucial part of the system. Assuming all life is also dead outside your hab, you are dead.

If it's something that kills animals but not plants/fungi then maybe you'd have options, but it's still a massively complex system that you are trying to keep stable.

Maybe a system of many different but self-contained habs would have more resiliency. If you lose some component to a blight then maybe the other hab has some different strain that is unaffected.

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SoylentRox t1_j8znqe0 wrote

Yes. And/or isolated equipment for most life support steps. So far example oxygen processing comes from growth tubes isolated in groups, and their feedstock supply gets sterilized before feeding into the machinery.

Energy and spare manufactured part intensive though.

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BlueberryTyrant t1_j8j0rtk wrote

You would need extremely advanced sensors tracking everything. You would also need to automate responses to each misbalance. It COULD be doable, but with so many moving parts, opportunities for failure are all everyone. The code running it all has to be perfectly stable, and a tech team needs to be on hand constantly. You also will still need ecologists on hand to provide an expert human’s eye on the system to catch deviations that the gear can’t.

We just aren’t there yet.

Frankly, unless we can achieve faster than light travel, this has to be developed to survive microgravity anyways, as an ecosphere is our only feasible way to keep people fed and watered and oxygenated and waste manages for years at a time. So you have to not only solve this, but you have to solve this for microgravity as well.

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SoylentRox t1_j8j4b4y wrote

Hardly. The bigger the system the larger your buffers can be. You are talking about trying to keep people alive in a hab the size of ISS and with I guess just a few hours worth of surplus oxygen.

A multi kilometer long hab with isolated grow machines (so toxins etc can't cause them all to fail) and months worth of food water and oxygen stored in tanks, and redundant power, and redundant manufacturing, and a few other hand nearby within a reasonable travel distance with enough population cap to house refugees... would be much more stable.

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