Obviously that problem is not overwhelming, but there is much work to be done. And if you are using it to survive, it can't fail. The same with the engineering. When you go, get one system working and then add to it.In the microgravity experiments, Gilroy is exploring the genetic basis of a phenomenon known to gardeners and horticulturalists for many years. Plants that grow up without mechanical stresses — due to wind, rain or other disturbances — "are much more susceptible to pests, are not as robust," Gilroy says, "but if you go into a greenhouse and shake the plants, they grow up more compact, strong, and resistant to stress. They are even more resistant to plant diseases."
It turns out that the same signaling system used to detect mechanical stresses like gravity is also used to defend against pathogens. That may explain why plants in space appear more susceptible to disease.
You say the technology exists, yet it doesn't. We don't have a booster that will give us the energy needed to do the deed. Falcon Heavy will eventually, at a price point that merely makes you scream. The Dragon capsule isn't crew rated and won't be for a while. And it isn't suitable to go to Mars. Elon Musk has spoken to that.
However we will do it, if it is worth doing. One interesting thought I had was the idea if one of the ways of paying for Mars would be to produce fuel there and export it back to LEO. Would the economics of unmanned transfer vehicles carrying fuel produced on Mars and boosting in .3 or so g's be cheaper then fuel produced on Earth and boosted up through 1 g. For that matter you could ship water as ice. With no life support to worry about would the mechanics be simpler?