The sapce has no end but humans are trying to explore what they can however we cant find out everthing about space.
Humans are going out to the space for a long time.They all go to space for dierent resons.Some of them are going plants some of them go for leaving a antena in the space other go to the intenational space station bıt at the end they return to earth.There is many reasons for that
Oxgen is one of them.If you are going to a station you can live in the station for a long time but you cant even stay there for too long if you are in a rocket the oxygen genereating thing is too big and heavy that you cant put in the rocket.
Radiation is a big problem.In space there is radiation everywhere you can think of and its affecting the astronot too.This why you cant live in space permanantly and the radiation is permanant on the body this why if a astronot takes enough radiation for his lifetime he cant return to space.To prevent this astronouts thet live in space should change time to time.
Rocket fuel is a problem too.Its not the hardest thing to do about rockets but its a major thing so if there is no rocket the rocket cant move.We cant put infinite fuel in a rocket thats why we cant go out in the space permanantly.
Food and water is basic but important problem in space.Usualy astronots take enough food for their expedition in space.But we cant take food because its covering a space in the rocket.
Humans themself is a problem.Because humans grow overtime and even if we had everthing i said humans would die of old age in space.
It is impossible and most probably will not be possible in the future too.Even if we cant live in space infinetly humans will probably will find a way to expand the space expadiations.