NASA on Friday said it would raise the orbit of the International Space Station by around a mile (1.6 kilometers) as a precautionary measure to avoid possibly being hit by orbiting debris. 'We're going to reboost the station/shuttle at 8:30 pm EDT (0130 GMT Saturday) by about a mile. Just a precaution to avoid a close approach from an object,' NASA said in a posting on the micro-blogging website Twitter. 'We've known about it for several days, it's not a concern, and we're doing this only as a precaution,' read the post. NASA officials did not describe what the space junk was, just saying that it was object 'number 84180.' Astronauts will use the engines of the US space shuttle Endeavour, which earlier docked at the ISS, to move the giant space station. It is not unusual to move the ISS orbit to avoid any of the millions of pieces of space junk orbiting the earth. On March 12, three astronauts aboard the ISS had to leave the station and take refuge in a Soyuz spacecraft due to the risk of being hit by the orbiting piece of a defunct satellite. 