CAPE CANAVERAL, Florida: Two Russian astronauts aboard the International Space Station are taking a spacewalk.

Oleg Kononenko and Anton Shkaplerov floated out Thursday after being held up at the hatch by a balky ring. They will relocate a construction crane on the Russian side of the space station. They also will install shielding on one of the station’s oldest compartments to protect against small bits of space junk.

Space debris is a major threat to the space station. NASA’s compartments were launched with armor already in place, while Russia’s were not. Station construction wrapped up last year, with the close of the NASA shuttle program.

The station’s four other residents _ American, Russian and Dutch _ monitored the spacewalk from inside.