Florida ? Spacewalking astronauts doing construction work outside the international space station Sunday made a disturbing discovery: what appear to be metal shavings inside a joint that is needed to turn a set of solar power panels.

The rotary joint, 10 feet in diameter, has experienced intermittent vibrations and power spikes for nearly two months. Space station managers were hoping a thermal cover or bolt might be hanging up the mechanism, which would have been relatively easy to fix, and were disheartened when Daniel Tani radioed to mission control in Cape Canaveral that metal shavings were everywhere.

“It’s quite clear that it’s metal-to-metal grating or something, and it’s widespread,” Tani said.

The astronaut used tape to dab up some of the shavings. It will be returned to Earth aboard Discovery next week for analysis. NASA is uncertain whether the flecks are actually metallic, possibly from the aluminum foil lining the thermal covers, or some other material.

This rotary joint, launched and installed just four months ago, controls the huge solar panel wings on the right side of the space station, to make sure they’re facing the sun. The joint for the left solar wings is working fine.