Washington - The space shuttle Discovery was on its way to the International Space Station on Monday as ground crews monitored a piece of space junk that could prompt a change of course.

A piece of an old satellite could require the ISS to perform an avoidance manoeuvre, forcing Discovery to slightly change course in order to arrive at the ISS on Tuesday.

Discovery launched Sunday for a 13-day construction mission to the space station after weeks of delays caused by concerns about hydrogen fuel valves and a fuel vent leak. NASA said there was no evidence of damage to the shuttle during the launch.

The ISS must occasionally divert its course to avoid space junk that could damage the station. On Thursday, it experienced a near miss that forced the crew to briefly evacuate into an escape capsule as a precautionary measure.

Discovery is to deliver the fourth and final solar panel to the ISS on a mission that will enable it to double the size of its crew to six astronauts. Three spacewalks are planned to install the solar panels and conduct other construction projects.

Discovery has seven astronauts on board, including Japanese crew member Koichi Wakata, who is slated to join the permanent crew on the orbiting space station. (dpa)