A leftover piece of an old Russian satellite forced six astronauts on the international space station to take shelter in a pair of lifeboat-like space capsules March 24, but zipped harmlessly by the outpost to the crew’s relief.

The piece of space junk was spotted too late to move the orbiting laboratory out of the way and flew as close as 11 kilometers when it zoomed by at about 2:38 a.m. EDT, NASA officials said.

While the chances of collision were remote, the potential danger of a hit was enough for Mission Control to order the station crew — which includes three Russians, two Americans and a Dutch astronaut — to seek shelter in two docked Soyuz space capsules just in case a quick escape to Earth was required.

It was the third time in 12 years that station astronauts took shelter from a close space debris pass. NASA and its partners typically order an avoidance maneuver when a piece of space junk is expected to pass close by the space station and there are several days of advance notice. But this latest space debris threat was initially spotted the morning of March 23, too late to plan a major maneuver, NASA officials said.

“We’re not too concerned about it, but it’s too late to do a [debris avoidance maneuver],” station flight director Jerry Jason radioed station commander Daniel Burbank of NASA and his crew late March 23.

According to NASA updates, the space debris is a remnant of the Russian Cosmos 2251 communications satellite. In 2009, the defunct spacecraft crashed into the U.S. satellite Iridium 33 in a massive space collision that created 2,000 pieces of orbital debris.

While the size of the space debris was difficult to pin down, it was “relatively small,” NASA spokesman Rob Navias said during NASA TV commentary of the space trash flyby.

NASA astronaut Don Pettit, who is the other American aboard the space station, radioed Mission Control March 23 to say he hoped to try and snap a photo of the space debris if it was possible. But the space debris whizzed by the space station unseen.

Space junk is a growing threat for astronauts on the space station, as well as other satellites orbiting Earth. According to recent estimates, there is about 6,000 tons of space debris in orbit today. NASA and the U.S. military’s Space Surveillance Network regularly track about 20,000 pieces of the debris in order to help other active satellites avoid collisions with the orbital trash.