Officials ordered that rockets be fired for 180 seconds at 1025 GMT to shift the orbit by 700 meters, mission control said in a statement. The new orbit will allow the unidentified object to pass 1.5 kilometers (a mile) away from the station.
“There is a one in a thousand chance of a collision, but we decided this morning that that was too high,” a spokeswoman for mission control said by telephone.
Three Russians and three Americans are on board the station, a $100 billion project involving 16 nations.
Astronauts briefly evacuated the station last year because of the threat posed by a piece of debris only a centimeter (half an inch) long. Experts say tiny objects could seriously damage a spacecraft as they travel at around 7.5 kilometers a second.
The United States says it has catalogued more than 15,000 items such as jettisoned rockets, shuttle detritus, and bits of destroyed satellites floating in space.
The amount has increased due to events like China’s 2007 shooting down of a defunct satellite, and last year’s collision of an old Russian military satellite with a telecoms satellite owned by Iridium.
