The basic needs of the colony can be put into a few categories:
- A stable (internal) atmosphere with the right temperature and humidity
- Protection against dangerous elements (anything from harmful radiation up to earthquakes or meteors)
- Sustenance - Air to breathe, water to drink, food to eat
Some planets are more habitable, some less. You could get lucky, and arrive at a planet with a significant atmosphere and even liquid water. You could also be colonizing a planet with no liquid water and no atmosphere - that’s going to make your life a lot harder. And don’t even attempt to colonize a Venus-like planet until you really know what you’re doing.
The most important materials for life are oxygen, carbon, hydrogen and nitrogen - the rest are present in such small quantities you can survive on stocks for a very long time, especially if you don’t let your population expand too fast. Recycling is the key on hostile worlds - the only input you need is waste and some energy to process it. Most of the colony is a closed environment, which lets very little waste go unchecked. We have brought a range of plants and bacteria to help break down personal waste and establish the basic air/food cycle. While those processes are extremely energy inefficient (just a few percent of the input energy is actually stored in the food - the rest is waste heat), they are very simple to implement and need very little maintenance, making them cheap in the early days of the colony. Eventually, we’ll want to supplement these with more industrial processes, where we have much better control over the output - and better efficiency and rate of production.
Radiators
- On worlds without atmosphere (or with bad temperatures), heat management is very important. Radiators are used to dump excess heat during the night or gather it during the day; this depends a lot on the environmental conditions. Pretty much everything produces heat and needs to mantain the temperature on optimal levels. Active refrigeration (on permanently hot planets) is even more tricky - so the ideal planet either has temperatures good for habitation, or is cold - heating is much easier than cooling (although, of course, solar arrays produce less energy further away from the sun).
Water
- Made from hydrogen and oxygen or extracted from ices (or the atmosphere/oceans, if any).
- Large amounts needed for basic sustenance and for food production.
- Also can be used as a coolant if present in sufficient quantities.
Oxygen
- Needed for sustenance in large amounts, however, also relatively easy to recycle in a closed environment. Byproduct of farming.
- Either available in the atmosphere, or in oxidised rocks or ices (carbon dioxide, water).
Carbon
- Needed for sustenance, important in industry (especially on planets with oxidative atmospheres).
- Extracted from atmosphere or ices (as carbon di/monooxide or methane), or the planetary crust (as various rocks).
Hydrogen
- Important as a fuel (in combustion with oxygen, as a fuel for fusion reactors and in batteries), in organic chemistry (food, various oil-based technologies), as a coolant and in semiconductors.
- Made from water/methane ices.
Nitrogen
- Needed for sustenance.
- Extracted from atmosphere or ices (ammonia, hydrazine).
Calcium, phosphorous, potassium, sodium, …
- Needed for sustenance.
- Extracted from the crust.
- In Game difficulty, those are replaced with a single group - Trace materials or something.