Orbiting junk won't affect space station

NASA said Thursday it would not have to adjust the position of the space shuttle Discovery and the International Space Station to avoid an approaching piece of space junk.

The U.S. space agency had spotted a portion of an old European rocket on Wednesday but concluded Thursday morning it posed no threat to the station or shuttle and their crews.

The piece of debris being tracked is approximately 19 square metres and is a leftover part of a booster from a three-year-old Ariane 5 rocket. NASA said its size has made it easy to track.

NASA estimates it would make its closest pass of the station about three kilometres away at about 10:06 a.m. ET Friday.

With no need to perform a debris avoidance manoeuvre, Discovery astronauts Danny Olivas and Christer Fuglesang went on the second spacewalk of Discovery's 13-day mission.

The pair of astronautsinstalled a new ammonia tank outside the station, a replacement for a tank removed during Tuesday's spacewalk.The astronauts stored the old tank in Discovery's cargo bay for the return trip to Earth next week.