I think this has been discussed before on ATS. But I'll bite and give my two cents because this fascinates me....
Mars lacks a dynamo at its core. The core is mostly molten Iron Sulfide and is less dense than Earth's core, hence the absence of a uniform
magnetosphere. But according to some stuff I read on NASA's website, there are regions that have higher magnetic fields. Perhaps, these may be prime
spots to construct "biodomes" as you suggest.
Secondly, the wispy atmosphere. Don't be confused when you read that it has 95% this or 90% that. It's relative to the density of the atmosphere of
the respective planet. The thin atmosphere of Mars has been dwindling away as its core has been solidifying and the atmosphere constantly being
bombarded by the solar winds/radiation. Without a strong enough magnetic field/shield, and enough gravity to hold on to its atmosphere, the Martian
air is slowly escaping/eroding into space. If only it was a little bit larger in size or denser with heavier elements, it could have had a significant
Thus, if humans wanted to "terraform" Mars, it would have to be an exhaustive continual process....unless (read further down).
If life did form there while the presence of surface water was present many eons ago, I would guess those creatures are dwelling in underground
aquifers that utilize the high iron content of the Mars geology. Very deep down.
Watching the successful landing of the Curiosity rover payload, I'm hopeful that we can land more massive equipment that can drill/excavate into the
Martian soil in order to make tunnels or depressions where we can construct "biodomes". But we can utilize the deepness of the Valles Marineris
canyon to drop down our "Biodomes" and slowly connect them together. The deepness and magnitude of such a canyon will be more suitable to protect
transplanted life to thrive. Firstly, by utilizing the canyon walls as protection from those planet-wide duststorms that Mars creates. Secondly, using
the depth and the shading against the solar radiation racing through a wispy, under-protective atmosphere. In such great depths that dwarfs the Grand
Canyon of Earth, there has to be some kind of separate atmosphere there.
The growing of agriculture within a "biodome" would be feasible, but would the difference in gravity and soil composition affect crop yields?
Inferring that Mars has a high iron content, I would have to guess that cruciferrous vegetables such as broccoli, broccoli sprouts, cauliflower,
cabbage would thrive on Mars' soil.
Mars, with its strange familiar tilt, seasons, rotation such as Earth, NASA claims that Europa has more "livable" space than the red planet:
But I guess, this all depends on the availability of water as well. Europa has lots of water. I was wondering that if a civilization such our current
one, can land on the Moon 6 times before my lifetime, land multiple robots on Mars, send satellites beyond the Solar System, then why are we not
aggrisively using/exploiting the asteroid field, and planetary moons that contain vast amounts of water and heavy elements?
But we are not alone, look into the Mars Society website.