On Friday, Discovery's astronauts spotted something floating away from their spaceship that turned out to be a little metal clip which broke off the rudder.
But engineers decided within four hours that its absence posed no danger for re-entry.
During the shuttle's mission, it installed a $1bn-Japanese-built laboratory, which is now the space station's biggest room and most sophisticated science workshop.
They also dropped off a new pump that the two Russians on board used to fix their toilet.
And the space station welcomed a new American resident, who took the place of astronaut Garrett Reisman, returning home after 95 days in space.
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