Let’s say it is the year 2050 and all of the logistic and financial constraints for delivering a crew of human colonists to Mars have been overcome, somehow.
It’s a one way trip for a couple of dozen colonists. Electrical power for the colony will not be a big problem, thanks to Mr Fusion, or whatever - so extraction of water and oxygen from local materials is possible. Heavy machinery and colony building materials will be supplied periodically from Earth, but the colony will have to be more or less self sufficient for food, indefinitely.
So… what’s actually on the menu? I think field-scale crops such as soy beans or wheat are probably impractical, as, most likely, is the notion of raising almost any kind of vertebrate livestock (although maybe catfish… except they probably need more water than all of the colonists put together).
The solution needs to be nutritionally complete. Maybe Earth can send consignments of trace nutrient pills, but pouches of dehydrated protein powder are not guaranteed. How will 24 adult humans be fed? Assume no magical GMOs or vat-grown steaks, beyond what is possible today.
Is it going to be algae, brine shrimp and crickets?
Jelly Donut looked a bit too crunchy for my liking.
So what are the crickets going to eat? - if they are to be fed on vascular plants, there needs to be a complete and reliable lifecycle for those - maybe chickweed - or they could be fed on something invasive that indefinitely perpetuates itself vegetatively - kudzu?
Actually, if they can manage the water, a dwarf cultivar of wheat would be a very likely inclusion. It provides a staple foodstuff and produces substantial oxygen per unit area. Rice is another likely option. It wouldn’t take as much area as you’d think in an aquaponic system.
If they can’t manage a stable, closed-loop system for growing crops humanity has been farming for millenia, what makes you think they can do it with edible algae?
Existing cultivars of wheat or rice do not have nearly enough protein for long term nutrition. You would need to have some kind of high protein food source, which probably means either some kind of fungus or either natural or simulated animal flesh. Crawfish or chicken are likely candidates because of their conversion of feedstock to protein. You’ll also want leafy greens (spinach, kale, cabbage, Brussels sprout, broccoli) and other minerals and vitamin carriers.
Note that there are no significant amount of nitrates on the Martian surface (from geological surveys so far); this, combined with the often months-long solar storms, low ambient pressure, and paltry solar incidence (less than half of what it would be at Earth orbit), will require the use of artificial sunlight and fertilizer. Hydroponics is probably the best way to go for high crop density and optimal nutrition, which will require power, water, and provision of fertilizers and arable soil, and of course the organic material (seeds, eggs, et cetera). If you look at the requirements to sustain a single person, even assuming that water can be sources in situ, we’re talking about hundreds or thousands of kilograms of material per person for sustainable food production, which will require a regular logistical chain is established and maintained.
Hydroponics + tilapia = aquaponics. Uses less waterthan maintaining animal protein and vegetable crops separately, and they wind up feeding each other.
Mainly because algae include simpler organisms than vascular plants - a closed tank of liquid with filtered air bubbling through it, and single-celled (or at least very simple multicellular) organisms blooming in it ought to be simpler to manage and less prone to failure than a crop of macroscopic plants with their root systems, different stages of development, etc.
A production line system for algae could conceivably be almost fully automated. A garden of plants (even if hydroponic, etc) will need more attention.
What about Test tube meat? I know nothing about the nuts and bolts of this - presumably it requires a high-quality lab where the ingredients can be synthesised, and the wiki article seems to suggest that in an Earth context it’s not going to be as economical as traditional farming for a long long time, if ever, but in a Martian context where there are no free supplies of plant-growing dirt and sunlight to take advantage of, that might turn out to be the easiest option.
And yet, we haven’t done so any significant scale. The only large-scale use of algae as human food that I’m aware of is seaweed–the cultivation of which involves a great deal more water than you will find in a hydroponics/aquaponics arrangement. Microalgae is used in supplements, but not–to my knowledge–as a food source in its own right. This is not to say it would be an insurmountable challenge, but it’s not the simple, obvious arrangement you make it out to be.
By contrast with your scenario, established food crops offer extremely well understood plants. After growing them for so long, we have an excellent idea of what they need and what can go wrong with them. If anything, growing them in a closed environment greatly simplifies matters. The psychological value of familiar foodstuffs can’t be ignored, either; at least some of the growing space will need to be dedicated to them.
