A piece of space junk smashed into the International Space Station and damaged the orbiting lab's robotic arm, according to NASA and the Canadian Space Agency.
A puncture in the arm's protective thermal covering was noticed during a routine inspection on May 12, but the nearly 60-foot robotic appendage remains functional, officials from the Canadian Space Agency confirmed.
The collision highlights the growing threat posed by orbital debris as the narrow band of space around Earth becomes increasingly crowded with satellites, spent rocket parts and other wayward objects. Experts have said the problem is magnified by society's dependence on satellite systems for telecommunications, GPS and other everyday conveniences.
It's not known what hit the space station's robotic arm, called Canadarm2, or when the incident occurred, but an investigation is underway.
The agency said the hole appears to measure roughly 0.2 inches across, and the damage is limited to a small section of Canadarm2.
"Despite the impact, results of the ongoing analysis indicate that the arm's performance remains unaffected," Canadian Space Agency officials said in a statement, calling the collision a "lucky strike."
The U.S. Department of Defense tracks more than 27,000 pieces of space junk, including approximately 23,000 objects larger than a softball. These bits of debris fly through orbit at up to 18,000 miles per hour, posing a threat to functioning spacecraft and a safety risk to astronauts aboard the International Space Station.
Over the course of the space station's history, NASA has had to perform at least 26 special maneuvers to dodge orbital debris that passed too close to the orbiting outpost.
In April, four astronauts en route to the ISS in one of SpaceX's Crew Dragon capsules were warned of a potential collision with space junk shortly after they launched into orbit. The U.S. Space Command later confirmed, however, that it was a false alarm and the object was not at risk of colliding with the spacecraft.