Six astronauts at the International Space Station took refuge in escape pods Saturday when a chunk of space debris flew dangerously close.

The U.S. space agency NASA said in its Twitter feed Saturday this is the third time a space station crew has had to evacuate because of orbiting space junk.

A discarded piece of the Russian rocket Cosmos 2251 was predicted to come within 15 kilometers of the space station.

At that distance, NASA said the astronauts were not at risk, but said it was evacuating them as a precaution, in case the debris were to hit. The escape capsules are the Soyuz spacecraft the astronauts use to return to Earth, both routinely or in an emergency.

After the debris passed safely, the astronauts returned to their normal duties.

Meanwhile, an unmanned rocket blasted off from French Guiana late Friday. The European Space Agency craft is carrying supplies for the International Space Station.