Are there aliens out there or are we alone in the universe? My advice to you is to be careful if you meet an alien. You won’t know where it has been.
The probability of primitive life on the nearest planets is very low. If the probability of primitive life is reasonably high, then the probability of that life developing intelligence like ours may also be very low. It could be that alien life did develop into a fully functioning civilization, but then it may have destroyed itself with war, disease and weapons of mass destruction.
In this regard, it seems likely that primitive life is relatively common, but that intelligent life is rare. Some would say it has yet to occur on Earth.
Recent experience (with the International Space Station) shows that it is possible for human beings to survive for many months away from Earth. However, the zero gravity of orbit causes a number of undesirable physical changes such as weakening of the bones, muscle atrophy and other adverse conditions. Remember: this is a one-way journey. There is no returning to Earth after a few months or years.
We are standing on the threshold of a new era. Human colonization on other planets is no longer science fiction. It could be science fact. And if we want to survive, our future lies in boldly going where no one has gone before.
I hope for the best. I have to. We have no other option.