Astronauts Tim Kopra and Dave Wolf spent nearly six hours outside the ISS
Astronauts have carried out the first of five spacewalks to be performed by the crew of the shuttle Endeavour at the International Space Station (ISS).
American astronauts Tim Kopra and Dave Wolf spent nearly six hours outside the ISS, attaching a large platform - the final piece of Japan's space lab, Kibo.
The section will be used in experiments requiring materials to be exposed to the harsh environment of space.
Endeavour docked on Friday, uniting a record 13 astronauts at the ISS.
Saturday's spacewalk, the 127th involved in the construction of the ISS, finished after five hours and 32 minutes, about an hour less than scheduled.
The astronauts carried out work to attach the 1.9-tonne platform to Kibo's two pressurised modules that were delivered to the space station last year.
Once in place, the crew on the ISS used the robotic arms on the station to manoeuvre the section into place.
The work fell behind schedule so the spacewalkers were not able to compete work to set up a payload attachment system on the station's exterior.
Their communication with their colleagues on the ISS was hampered by heavy static from the microphones in their helmets.
But Nasa said the communication problems did not pose a safety risk and they hoped to resolve the problems by the next spacewalk, scheduled to take place on Monday.