Astronauts may be at increased risk of premature aging due to exposure to radiation found in space, suggests a study that could have major implications for long-duration space travel. The findings from the Lombardi Comprehensive Cancer Centre at Georgetown University Medical Centre in US shows that astronauts may be at increased risk of colon cancer due to exposure to the high linear energy transfer (LET) radiation found in space. The study shows that the high-energy radiation found in space may also lead to premature aging and prolonged oxidative stress in cells.