Astronauts Sunita Williams and Akihiko Hoshide made a spacewalk to finish the replacement of a key component on the International Space Station. The EVA (Extravehicular Activity) on 5 September lasted six hours and 28 minute (ending at 1734 GMT. After using a toothbrush to clean metal shavings/debris from a bolt hole they successfully drove home a new bolt to latch the replacement Main Bus Switching Unit No 1 (MBSU No 1) into place.
This latching operation failed due to this blockage during the previous spacewalk on 30 August 2012. The replacement allowed solar array power to be restored to two (of eight) main solar arrays had been lost while the replacement was completed). One of the eight solar arrays continues to be faulty due to a separate voltage regulator short circuit.
During the spacewalk, the astronauts also installed a new camera on the Canadarm 2 robotic arm.