Minimum starting population: 50 adults. Less would be too great a genetic bottleneck.

Remember, these people will be doing heavy work, so their needs will be far above the ordinary sedentary person in our society.

Food requirements (dry weight): assuming 3,500 Kcalories per person per day, about 500-1000 grams per day, depending on fiber content. Let us take 1000 grams per day as a base figure.

Drinking water requirements, including water obtained from food: 5,000 grams per day.

Personal washing water requirements, 5,000 grams per day, minimum, probably more like 10,000 grams.

Domestic water requirements, 10,000 grams per person, per day: includes laundry, dishwashing, ..., other uses not covered above.

Food preparation energy per person per day, no less than 10,000 Kcalories.

Food preparation water per person per day, 1,000 grams, min.

Oxygen consumed, per person, per day, 1,500 grams.

To provide these resources, by photosynthesis, requires a rather large collection area. Assuming 2% efficiency of photosynthesis, and remembering that sunlight on Mars is less than half that on Earth per square meter, when dust is factored in, this means quite a bit of area. Also, recall that the majority of dry weight of all plants is cellulose, which is not digestable without enzymes that we do not produce. I have estimated (by calculations I do not give here, factoring in many kinds of losses) that it would require about 100 square meters of greenhouse surface per person. This is the area of a square 10 meters on a side. The plants must be covered to keep them warm, and to collect oxygen for breathing, but might not need to be pressurized, just sealed to avoid water and oxygen losses. But pressurization might be needed, and would add greatly to the strength and materials required. Now, we have 50 * 100 = 5,000 square meters of greenhouse. This is not small by any means, but a rectangle 50 meters by 100 meters. Water would need to be extracted from the Martian soil and perhaps demineralized (if the solute content is too high), pumped into pipes and transmitted to the greenhouse. So now we have covered food, right? Wrong. Remember, a self-sustaining colony requires births to replace inevitable deaths. So the food requirements go UP as the little people arrive. A significant portion of the equilibrium population will be too young, or (eventually) too old to work. Therefore, I double the amount to 10,000 square meters of greenhouse. If merely sealed, it might require as little as 20 kilograms of structural material per square meter. If sealed, figure no less than 100 kilograms per square meter. The latter would mean that 1,000,000 kilograms, or 1,000 tonnes of material. That is just for the greenhouse.

If the colony is to grow, then it must build new housing and enlarge the greenhouse on a continuing basis. This requires mining, and perhaps growing of trees for wood. This latter makes the greenhouse area go up again.

Mining requires copious amounts of water. Just ask any miner. The requirements of water could be reduced, but only so far. Losses are inevitable, and therefore water replacement must be done constantly.

Manufacturing of furniture, appliances, .... requires metals and plastics. Metals can be mined, but the ores may be quite distant from one another and therefore, there must be some system of transporation to bring either the ores, or the buld metals to the colony for further processing. Mining equipment would be required. Spare parts would need to be made, thus requiring machine tools.

Some plant matter could be converted into plastics, requiring chemical reactors and factories.

And so on. The total starting requirement would not be less than 10,000 tonnes. That is not to say that the establishment of a human colony on Mars is impossible, or even impractical, but rather an enormous undertaking. Don't think that it can be done for less than a round-trip manned mission, it can't.

Farming in a Simulated Martian Environment

LSS for EVA

Human Life on Mars

David F Mayer