Scientists have long known that traveling to space takes a toll on the body?"but they're still trying to figure out just what that means. But according to a new study, lengthy voyages outside Earth's gravity can change an astronaut's brain. At the center of the brain are four, fluid-filled cavities called ventricles, which help keep the organ cushioned and floating in the liquid that surrounds it. During spaceflight, these ventricles expand by In the new paper, published last week in the journal Scientific Reports, scientists assert that astronauts' ventricles expand more during longer missions?"and it could take more than three years for them to return to normal.