Surprising effects of being in space on the human body

Scott Kelly (right) was in space for 12 months while his brother Mark (left) was monitored at home (Image: NASA)

An American astronaut experienced multiple biological changes in space but returned to normal - with some exceptions - after coming back to Earth, according to a study involving twin brothers that shed light on how space flight affects the human body.

In research published on Thursday, scientists compared Scott Kelly to identical twin Mark Kelly after Scott spent 340 days in orbit on the International Space Station and Mark remained Earth bound.