Are Humans Fit For Space? A ‘Herculean’ Study Says Maybe Not
At the same time, his twin brother Mark, also an astronaut, tested his intracranial pressure back on Earth. The idea behind the study has a simple logic: Because the twins share the same genome, comparing the changes that occurred while one was in space and the other on Earth would give new insights into the impact of long-duration spaceflight on human health. During their NASA careers, Mark was the pilot or commander of four Space Shuttle missions; Scott piloted and commanded two Shuttles and spent six months on the ISS before his year in space.
Source: www.wired.com