That's why the fundamental solution to both the ageing problem and space exploration is not biological. Humans are fundamentally adapted to live/reproduce on the oxidizing and wet environment on Earth. Rather than bring out a mini Earth environ each time we go to space, we should start thinking about how we can just bring out our mind. It would be much more sustainable in the long run, maybe even on Earth itself.
Why do we even need to colonize space anyways? It's not like overpopulation is going to be a problem anymore, and someday in the future, we'll be able to solve problems like environmental degredation and climate change. There's just not any benefit to exploring space. Besides asteroid mining (which can be done with robots), there's not much up there worth our time, except scientific research.
What about all the technology that, while developed for spaceflight, provides huge benefits to the earthbound masses?
What about meeting other civilizations if they exist, or else learning why they don't?