We have hydroponics. We can create soil over time, modeling the same cycle we have on Earth. This makes the problem more quantitative, rather than qualitative.

We have hydroponics. We can create soil over time, modeling the same cycle we have on Earth. This makes the problem more quantitative, rather than qualitative. The bigger problems are still radiation and lack of (Earth) weight. For both we have ideas, some data and results, and both need to be addressed more. Other issues, like meteoroids on the way there and back again, or lack of resources, seem to be of a lesser caliber.