International Space Station Commander Fyodor Yurchikhin (R) and Flight Engineer Oleg Kotov extend the Strela boom during their spacewalk May 30, 2007. The spacewalkers will install Service Module Debris Protection (SMDP) panels on the Zvezda service module and reroute a Global Positioning System antenna cable during their estimated six-hour spacewalk. (Xinhua/Reuters Photo)

    BEIJING, May 31 (Xinhuanet) -- Protective panels designed to shield the international space station from harmful space debris were installed Wednesday by two Russian cosmonauts.

    Commander Fyodor Yurchikhin and flight engineer Oleg Kotov exited a hatch on the Russian side of the space station at 3:05 p.m. EDT. The spacewalk lasted about five and a half hours.

    Both men were tethered during the spacewalk to keep them from floating away. The station's third occupant, U.S. astronaut Sunita Williams, remained inside.

    Space debris includes objects such as discarded rocket parts, planetary dust and rocks. Scientists consider it the greatest threat to the space station, orbiting about 220 miles (350 kilometers) above Earth.

    The 17 protective panels, each about 2 feet by 3 feet (60 by 90 centimeters) and weighing about 20 pounds (9 kilograms), were delivered to the station last December and left outside in a formation called "the Christmas tree."

    The cosmonauts installed five of the panels on a Russian section of the space station, and the others were to be put in place during a spacewalk next week.

    The cosmonauts also successfully rerouted a cable for a navigation antenna that will be used later in the year for the first flight of a new European cargo vehicle.

    Wednesday's spacewalk was the first of two scheduled a week apart. Yurchikhin and Kotov will perform another one next Wednesday with similar tasks, including depositing canisters containing biological experiments outside the station.

    (Agencies)