Eyes on junk as shuttle nears ISS

US and Russian experts tracked a piece of space junk about the size of a mobile phone that was projected to pass dangerously close to the International Space Station as the Discovery shuttle hurtled through space to dock with it.

Hours after Discovery's launch on Sunday, Nasa said a team in Houston was tracking a 10-centimetre piece of debris believed to be from the Soviet-era Kosmos 1275 satellite, which disintegrated shortly after it was launched in 1981.

Current projections put the object on a trajectory that would take it to within three-quarters of a kilometre of the International Space Station, Nasa mouthpiece Kylie Clem told AFP.

"The teams here in Houston and in Moscow have developed a plan to move the space station tonight if necessary but that hasn't been decided yet," she said from Johnson Space Centre in Houston, Texas.

Last week, the ISS's three-member crew had to temporarily evacuate the space station and seek shelter in a Soyuz capsule when a smaller piece of space debris passed about 4.5 kilometres from the orbiting space station.

Although "debris avoidance" manoeuvres are not unusual for the space station crew, the fact that the Discovery shuttle is on its way to rendezvous with the orbiting ISS adds another dimension to such moves.

Last week, the ISS crew evacuated the ISS instead of moving the station to dodge the space junk because Nasa had scheduled Discovery's launch for Sunday and the ISS "needed to stay at the same altitude", Nasa mouthpiece Laura Rochon said.