An unusual space traveler named Fred is orbiting Earth aboard the International Space Station. His job? To keep astronauts safe from space radiation. Fred, who’s spending the next four months on board the International Space Station (ISS), will measure the amount of radiation to which astronauts are exposed. High-energy particles that pass through the human body can disrupt the way cells function. Although no astronaut has ever been diagnosed with space radiation sickness, excessive exposure could lead to health problems.