Johannes replied to me:
I think full live support with food production is unrealistic at TL7
and overly optimistic at TL8.
The real question will be the efficiency. Vehicles makes it
all-or-nothing, but could a TL7 system reach 90% recycling rate? Could
there be 99% at TL8?
I would not use the food production option before TL9, unless it is a
vehicle, that should follow genre conventions, rather then realism.
It could work for mixed TL or postapocalyptic settings though, if the
organisms already exist, and only the holdingplaces need to be built.
Without life support, a human needs 12 lbs. of food and water per day.
That water is for food preparation only, it seems. With full life
support, this becomes 2 lbs. of food. That's 7,300 lbs. per person for a
decade-long mission. Now imagine a hydroponics system could save 6,600
lbs. of food.
Thomas replied to me:
I should have put quotes around garden: it does not matter whether your hydroponic
„garden" looks like a regular garden or not, it is still a complex eco system.
Putting the plants into buckets and connect them with tubes and pumps might simplify
that system to some extend, but the complexity remains significantly high. And to be
honest, I think it would make it even less self-regulating …
Perhaps you remember those ecosphere experiments that failed due to massive
problems with the hydroponics in the end.
With soil, you need worms to ventilate it. With hydroponics, you can do
without them in this role. Perhaps some worms in the dung heaps, but
that's another compartment.
It is important that there is a balance between O2 and CO2 in the atmosphere,
not only for the garden. So when plants do consume O2 at night, I assume that
they do this due to the absence of light in that period. So it should be
possible to control that CO2/O2 balance by switching the light on and off.
Extended periods of darkness will of course affect the production of
nutritions, but on the other hand, if not so much O2 is needed, there is a good
chance that also less food is needed.
I'm envisioning a scenario roughly like this:
A space mission is going to take several decades of flight time,
subjective time, plus a lengthy stay at the destination to make it all
worthwhile. Building a generation ship was considered and rejected for
various reasons. Instead, the ship uses cryonic capsules.
At the destination, the ship computers (no true AIs) will prep the life
support; this is sufficient for a small fraction of the crew. They mine
asteroids to build a habitat. The key components like the computers are
part of the payload while crude stuff like walls or pipes is
manufactured out of local raw materials. As the habitat is expanded,
more and more crew come out of cryosleep. After some years the crew
refits their ship for the return trip. Either all of them go home or a
flight crew returns the ship while most become colonists. This might be
decided only after arrival, when the suitability of the destination is
evaluated.
Problems:
- Is the total life support going to run "idle" for several decades, or
is it going to be restarted from a total shutdown? Both are difficult.
- Is it possible to predict what trace materials for the biosphere can
be found and what needs to be carried along? Spectrographic analysis of
the destination?
- How many "imported key components" does it take to build a station
with life support and a shipyard?
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