The crew of the space shuttle Discovery have successfully touched down on Earth after their mission to the International Space Station. Earlier a half-metre long metal clip fell from the shuttle but NASA approved the Com

Commander Mark Kelly and co-pilot Kenneth Ham fired the shuttle's breaking rockets to take the ship out of orbit. There were seven people on board the shuttle, which took an hour to descend to NASA's Flordia spaceport.

On Friday NASA said that the spaceship was safe for re-entry and that the missing clip – one of three that hold down thermal blankets on the rudder and the speed brake – would have no significant impact. A protrusion in the same area at the tail, which was reported by the astronauts around the same time, was also found not to pose a danger.

Ever since the Columbia tragedy five years ago, any shuttle part seen floating away in orbit is immediately investigated by NASA.