Astronauts have finished installing a solar power unit on the International Space Station Tuesday, during their third spacewalk.
Spacewalkers Scott Parazynski and Doug Wheelock helped guide astronauts inside the station as they used a robotic arm to install a 16,000 kilogram beam to the end of the station.
The beam's large solar panels will generate electricity for the addition of a European research laboratory in December.
Astronauts Tuesday also plan to inspect a malfunctioning joint that is key to generating electricity for the station. They will compare the joint to a similar undamaged one.
During a spacewalk Sunday, two astronauts found metal shavings in a joint that allows the array of panels to rotate to follow the sun.
NASA says shuttle Discovery will return to Earth a day later than originally planned (November 7) to allow time to inspect the damaged joint.
Astronauts will perform a fourth spacewalk Thursday before the crew gets some off-duty time and prepares equipment for a fifth spacewalk Saturday.
Some information for this report was provided by AFP, AP and Reuters.