Minimum TL for a self-sufficient Vault City or equivalent bunker?

[vicky_molokh]

Greetings, all!

I'm trying to figure out the minimal TL at which it becomes possible to construct a self-sufficient sealed complex, such as the various underground Vault Cities of Fallout. Optionally, this includes figuring out split TL if some components appear earlier than others.

The problem of having constant power for many processes maybe requires TL7.
For life support, Open Space (from Spaceships) is technically TL7, but I'm wondering if it's possible to do earlier - I think an important question is the availability of full-spectrum light sources for plants.
Other issues of life support might also allow or not allow below-TL7 implementation.

Edit: I'm working on the assumption that mining deeper is allowed, as is digging to the sides for expansion. It just has to survive without reaching the surface (shallow water counts as surface, but if somebody has comments about a 100m+ deep underwater base, suits the purpose about as well - just have to know which of the projects is discussed).

Opinions?
Thanks in advance!

[Ed the Coastie]

I read somewhere* that a self-sustaining colony could be maintained in a large cave system using the technology of the late 19th Century (late TL 5 or early TL 6). As you said, power is going to be a bit of a problem...but once the colony is established, it could easily be maintained.






* I don't remember for sure where I read it -- it was several years ago in -- but I think it was in an old copy of OMNI magazine.

[Purple Haze]

It is debatable if we even currently have the technology. Certainly the experiments we've done have had mixed success at best. (See "Biosphere 2")

Plants don't need a full spectrum just a red light and a blue light in varying proportions depending on their stage. I have grown crops indoors, metal halides for growth, high pressure sodium for flowering. Fluorescents will do in a pinch, but the normal ones lack enough red. Getting rid of excess heat is the largest problem.

Basic problem with closed systems is that if one is slightly off of equilibrium they tend to go bad quickly.

[Sam Baughn]

Didn't we try (and, if I recall correctly, fail) to make a closed ecosystem in the late ninties? Called Biosphere 2 or something like that, I think.

EDIT: http://en.wikipedia.org/wiki/Biosphere_2

Apparently they had a lot of problems keeping the system stable for 2 years. This suggests to me that TL 8 is probably the bare minimum and TL 9 would probably be desirable before commiting to putting several generations of people in there.

[malloyd]

Originally Posted by vicky_molokh

The problem of having constant power for many processes

Commercial geothermal is no later than TL6, and should work. These things always have a lava flow somewhere for adventurers to fall into anyway right?

For life support, Open Space (from Spaceships) is technically TL7, but I'm wondering if it's possible to do earlier - I think an important question is the availability of full-spectrum light sources for plants.

It's only hard with incandescents, arc lamps can easily have much higher brightness temperatures, and are solidly TL5 technologies.


Certainly most of the problems you'd face are understood by the end of TL5. I'd have no problem believing a fully closed cycle at TL 5+1 if there were better incentives for developing one. Historically, well, we haven't got a completely closed life support system yet, though systems have been demonstrated for over a year that only need a pound or two per year of trace nutrients. And closing those last few micronutrient loops is really only hard because our design driver is largely space-flight related, where mass and volume constraints matter a *lot*. If you can't do it on less mass than a decade's supply of the micronutrient weighs, there's not much point for a spacecraft. Underground complexes have an easier time there.

[vicky_molokh]

Originally Posted by Perfect Organism

Didn't we try (and, if I recall correctly, fail) to make a closed ecosystem in the late ninties? Called Biosphere 2 or something like that, I think.

EDIT: http://en.wikipedia.org/wiki/Biosphere_2

Apparently they had a lot of problems keeping the system stable for 2 years. This suggests to me that TL 8 is probably the bare minimum and TL 9 would probably be desirable before commiting to putting several generations of people in there.

Apples to oranges, IMHO - B2 is a mere 1/100th of a square kilometer in area, and is dedicated to trying to create a diverse biosphere representing many climates, not a system dedicated to allowing the optimal existence of a human-life population in a closed space.

[Langy]

An RTG would be a good power source for a Vault. No moving parts, so they last an awful long time without maintenance - and that's probably going to be the crucial thing here, along with life support.

If you had a big enough vault with enough spare parts and people in it you could probably do it at TL6, sure, maybe even lower if you found a suitable enough plant that grows underground without sunlight. The hard part is making it not the size of a city and having it last a significant amount of time.

[Witchking]

Also if you are going with the Vault setting...you only need to be near-perfect...

If someone goofs or a critical part is damaged you can always find some faceless guy to go OUTSIDE...

[vicky_molokh]

Originally Posted by Langy

An RTG would be a good power source for a Vault. No moving parts, so they last an awful long time without maintenance - and that's probably going to be the crucial thing here, along with life support.

If you had a big enough vault with enough spare parts and people in it you could probably do it at TL6, sure, maybe even lower if you found a suitable enough plant that grows underground without sunlight.

That's the problem. No sunlight, no photosynthesis. No photosynthesis, no oxygen. Fungi don't exactly need sunlight, but aren't plants either.

Originally Posted by Langy

The hard part is making it not the size of a city and having it last a significant amount of time.

Oh, making it the size of a city is actually good. Making it last 60+ years is pretty important.

[vicky_molokh]

Originally Posted by Witchking

Also if you are going with the Vault setting...you only need to be near-perfect...

If someone goofs or a critical part is damaged you can always find some faceless guy to go OUTSIDE...

No, just using it as an example. Going outside should actually not be an option for at least half a century.