No, you can build the greenhouses in-situ. We have already worked out how to produce metals and polymers from martian resources.
> This is already hard to do in deserts or in the Polar regions, where we have plenty of oxygen and free moisture flowing in the atmosphere.
Sure, there will be considerable challenges. I don't see anything that will be insurmountable.
links?
No, you can build the greenhouses in-situ. We have already worked out how to produce metals and polymers from martian resources.
> This is already hard to do in deserts or in the Polar regions, where we have plenty of oxygen and free moisture flowing in the atmosphere.
Sure, there will be considerable challenges. I don't see anything that will be insurmountable.