Keep in mind that with Mars low atmospheric pressure, buildings and people (in space suits) do not lose as much heat as it would seem. All of the studies that I have seen for Mars habitats have required more cooling capabilities than heating. A green house for example that is a hybrid of natural and artificial light would need pretty decent cooling capabilities unless you used some of the most efficient (and expensive) led lights that are beginning to appear. By new and expensive I mean several dollars per emitter and not generally or yet available, but the price will come down as yields improve.
Indeed. One of the things I learned in biology is that plants DO use O2 at night. Not as much of it as animals, of course. Heck, I wouldn't be surprised if roots often depend on atmospheric O2. So if you're starting up a greenhouse you're either going to need to spike it with some O2 or provide 24-7 light to your seedlings so they're continously producing the O2 they need. Even then you're likely to need a dedicated sprouting section that provides an O2 source until the seedlings develop enough chlorophyll for photosynthesis.
As for the lights, I wouldn't picture anything else being used - unless you're talking about some light source being produced on mars in favor of shipping it from earth. The cost of launching anything into orbit, then putting it on a course for mars makes the cost of the lights insignificant, so why not use the best?
Also any serious Mars base plan involves some form of nuclear power source even if it is not a full blown reactor. These can provide all of the high or low grade heat you could ever want.
Pretty much. As long as you're putting in a nuclear reactor on mars, might as well go whole hog and make it a combined plant. Higher efficiency for win!
I don't think that it'd be a bad idea to send over an automated greenhouse first. Get the O2 levels up to 'breathable', then use mechanical/chemical systems to seperate out the O2, either into a chemical dump or pressurized tanks. Keep balancing out the atmosphere to maintain proper pressure and CO2 levels by sucking in more outside atmosphere. Possibly using regenerable CO2 scrubbers to pull only CO2 in from outside(keeping nitrogen or whatever else is out there from eventually choking up the system).
The harvesting systems would likely be interesting. Then again, deprived of O2, you're not going to get much in the way of decomposition, so you'd just sequester whatever plant matter you don't want. No oxygen in freezing temperatures(IE outside) wouldn't lead to decomposition anytime soon in human terms.
Don't send humans until you have enough O2/plant matter to act as a food supply for a year or five. And yes, initially for a colony project I'd make most of the trips one way.
