How much land does a colony on Mars need to start off?

Question

Assume that we need just the following Martian resources for our colony:

• O₂
• N₂
• H₂O
• Regolith for radiation shielding
• Regolith for construction
• Regolith for printing tools
• Martian compounds for rocket fuel

From The resources of Mars for human settlement - Meyer TR and McKay CP

How much surface area do we need on Mars to establish collection of all these resources for a colony of 7 people (max capacity of the Dragon)?

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Other things to consider:

• Habitat
• Food production

• Variations in approach

  SF pointed out a variety of assumptions:

  Assumptions: water recovered from regolith or air? Oxygen by distillation of CO2 or cyanobacteria farm? Power solar or nuclear? Surface/subsurface shelter or cave?

  Out of the plausible options that have been presented in scholarly/technical discourse, you should assume that which requires the most surface area. If you wish, you can also specify the lower surface area requirements of the alternatives.

• Landing site for deliveries from Earth (no need to estimate for launch facilities)

Answer 1

Of these, the only one that isn't well known is Nitrogen. The Nitrogen levels at Mars are somewhat unknown, but expected to be pretty low overall. Of course, Nitrogen isn't required for a colony of what you have.

The one thing that actually takes area is to grow food, which you did not include. On Earth, growing crops requires about 1 acre of land per person per year. I believe Mars habitats would be closely monitored in temperature, and have less meat, which would increase the yield by a factor of two. More intense methods could make that to a single acre, as is discussed at World Building. In fact, it could be much less than this, but...

In The Martian, assuming a 2500 calorie diet of pure potatoes requires about 370 m^2 of land. Let's increase that to 500 m^2 to allow for other types of crops to be grown to give at least some variety. That also gives about 1 acre of land (4046 m^2) feeding 7 people So far so good, 4000 m^2 of farmland would be the minimal required.

Beyond this, the shelter could in theory be below the farmland and be just fine. Give, say, 500 m^2 for stuff on the surface, and one would be more than fine. Let's even round up, and say that about 700 m^2 of land is required per astronaut.

Fuel for the return would come from the atmosphere. The amount of regolith required to make the water would vary depending on where you land, but might require some significant investment. If you are planning on purely solar powered operations, an area of 6600 m^2 of panels would be required to give 100 kWe of power. Nuclear is highly recommended, not only because it is more dense power wise, but also produces waste heat, which can be used for heating the habitats.