Nobody is ever going to put a permanent colony in microgravity. Colonies will either be on the surface of a planet/moon, or will use a tether-and-counterweight to generate artificial gravity through rotation. How to do this has been known for decades, if not centuries (https://en.wikipedia.org/wiki/Artificial_gravity#Rotation), and is trivial compared to the huge engineering challenges of cost-effectively launching thousands of tons of life support equipment to maintain a viable population.
The concept of artificial gravity is well known but trivial it is not. It would either take a giant ring or dumbbell station or require spinning very fast. This will cause significant engineering problems when dealing with gyroscopic precession in a gravity gradient environment.
Maybe, maybe not. Six months in microgravity doesn't seem to cause serious problems. Maybe people will just do six month tours. One Russian guy has been up there for 800 days, and wants to hit 1000. He'll probably need some rehab when he comes back down, but so do most people who deploy to war zones.
Just to clarify: that is a total lifetime duration in space, not continuous. The record was broken just a few weeks ago, at least two people have stayed in space for more than 800 days.
Longest human space flight was 437 days (or in that ballpark). There are no plans to attempt breaking this record currently.
Whatever the environment looks like, I think it will take at least several generations of offspring (born and live their lives in space) to adapt to the new environment (unless we truly can replicate the space environment almost identically to earth).
If you think about it, how many millions of years has natural selection spent adapting humans to Earth? It's almost as if genetic engineering is the only possibility that humans will adapt quickly enough to make outer space viable as a livable environment.
There's likely very little adapting to do. What doesn't work is expecting to live in microgravity long term, and then come back to gravity. There's no talk whatsoever about what happens if you never go back to gravity. Until they allow a volunteer astronaut to spend the rest of their life in space without returning, we won't have a real-world analysis of what happens to one's body as they age.
And of course the truly interesting experiment: a child born in space, who spends their entire life there. Of course, "child abuse" means this will not happen in our lifetimes. Let alone seeing what 2-3 generations of space-bound life results in.
How is that supposed to work? The pressure of natural selection has already stopped in most countries, individuals that would have been removed from the gene pool in more resource constrained times can now reach old age. And that is a good thing!
We would be venturing into genetic engineering to breed "space humans", which is at least problematic.
Natural selection has not stopped ant can not stop.
Here in the USA, currently trans fats are killing people. Some people can tolerate trans fats more than other people can. We evolve to tolerate them.
The same goes for every other not-good-for-you kind of thing we eat. People who tolerate it (or find it nauseating) will survive longer.
Now that many do survive to old age, natural selection can work to eliminate menopause. Today there are those who hit it at 30 and others who hit it at 50 or even later. Some leave more offspring, and this is all that is needed to drive natural selection. We evolve, and always will.
Good question. I feel natural selection works in more ways than just "survival of the fittest" sense of the term.
For example, for millions of years our bodies have become adept at precisely the amount of gravity Earth pulls on our bodies. Whether or not that has affected the species ability to reproduce, or if it's consequential to our ability to live comfortably in space, is another question, but I feel there are more ways evolution has affected our genes (to be more perfectly adapted to Earth's environment) than we may realize.
Maybe robots can colonise Mars for us and we can stay here. We are probably just a stepping stone in the evolution of "life" forms that will go on to colonise space - AI and machines.
Not going to happen soon but seems plausible, very hard to sustain human life over long space journeys vs. self-healing, self-replicating machines running on nuclear or fusion
Your statement completely ignores evolution and the human body's ability to adapt to its environment.
Sure, the timelines for such adaptations to develop are totally unknowable at this point, but you should never say never, especially with the progress being made in the field of genetics.
Evolution requires selection. Or in other words, having humans evolve into surviving in microgravity would require letting the least adapted people die of it for tens of generations. This doesn't seem like something that potential space colonists would be exited about.
Or we could select astronauts for longer missions based on these results. A person without legs (a double amputee, perhaps) might be able to perform all necessary activities while in orbit, but not suffer some of the ill effects.
