It is well known that spacewalking astronauts remodeling the international space station on Sunday found signs of trouble in the electrical power system that could stall plans to add European and Japanese science modules on upcoming missions.

What isn't as well known is that Astronaut Dan Tani found metal filings when he pulled away the cover on the rotating mechanism that turns outstretched solar panels on the station's far right side. Those tiny metal filings could hinder the solar mechanism's ability to generate electricity for the station.

Solar power rotating mechanisms on the left and right tips of the station's solar power system turn the wing-like panels to track the sun as the orbital base circles Earth. The solar power electricity they generate solar powers the station's life support equipment, communications and flight control systems, as well as solar power experiments within the U.S. science module.