NASA’s astronaut Scott Kelly gene expression has changed after a prolonged stay in the International Space Station. It was found that only 93% of his genes returned to normal function and the rest are still changed. The genes were compared to that of his brother who stayed on Earth along with pre-flight samples.
Normally astronauts remain in space for six months but NASA is experimenting on what effects on the human body and mind prolonged stay in space causes.
The experiments are a stepping stone for the later missions on Mars and on the Moon that NASA plans to make and need all the data for them to happen.
It is apparent though that travel out of our planet is still very hazardous to the health of our body and human experimentation is a bit questionnable. Regardless this is what is happening and will continue to happen for quite some time.