A HUMAN flight to Mars has been the subject of science fiction stories for decades. But according to NASA, the first step in getting astronauts to Mars is already in progress. NASA astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko are living aboard the International Space Station (ISS) for a year. The reason they are doing this is to collect information on how their bodies and minds deal with long space journeys like one to the red planet. The mission (任务) started on March 27, 2015 and is now halfway through.