Re: Carbon Dioxide
"'ve seen something, somewhere, about how to solve that part...
... Oh, I remember, they call them "plants"..."
Well oddly enough I'm a physical scientist and I've come across them - well at least on Earth where they have a reasonable supply of carbon dioxide and oxygen.
Problem on Mars is the high percentage of carbon dioxide still represents a pitifully small amount due to the very low atmospheric pressure and there's very little oxygen which plants need as well. Now I'm not a botanist so I can't tell you if current plants will grow under such conditions but I'd bet it's not too likely.
Oh I wonder who might know ? Maybe NASA
"The plants would probably be housed in a greenhouse on a Martian base, because no known forms of life can survive direct exposure to the Martian surface, with its extremely cold, thin air and sterilizing radiation. Even then, conditions in a Martian greenhouse would be beyond what ordinary plants could stand. During the day, the plants would have to endure high levels of solar ultraviolet radiation, because the thin Martian atmosphere has no ozone to block it like the Earth's atmosphere does. At night, temperatures would drop well below freezing. Also, the Martian soil is poor in the mineral nutrients necessary for plants to thrive."