why the life span gets longer by entering into space
Answers
One of the many things we don’t know for sure. But we do have data, thanks to our life sciences experiments on the ISS.
As has been mentioned, the body experiences reduced stress, however that leads to a number of detrimental factors like bone and muscle degradation, heart malformation, and the “chicken leg” syndrome, causing one’s fluids to collect in the chest and head. Our bodies are adapted to living in a state of constant low-grade physical stress.
Also, long duration spaceflight increases the risk of cancer due to radiation bombardment. NASA spaceflight requirements on this are very strict, and the risk of developing cancer over an astronaut’s lifetime may not increase by more than 3% (bad news for your manned Mars mission).
So all of that seems pretty grim, and living in space may never actually be a feasible option. Not sure why you’d want to, I like not feeling like I have a head cold, personally. But that’s just me. What we don’t know is what the actual, measurable effects on human lifespan these detrimental things actually have. It will almost certainly shorten lifespan, but by how much? We don’t yet know.
It also appears that the damage is reversible for the most part. Astronauts appear to fully recover from the physical effects of prolonged microgravity