Sunita Williams, colleague fail to do maintenance task

Indian-American astronaut Sunita Williams and her Japanese colleague, who ventured outside the International Space Station to perform maintenance tasks, have failed to bolt a new power-switching unit into place outside their home in orbit.

During the spacewalk, 46-year-old Williams and Japanese flight engineer Akihiko Hoshide were ‘unable to install a new Main Bus Switching Unit [MBSU] on the International Space Station's s-zero truss’,American space agency NASA said on Friday.

After removing and stowing the failed unit, they had difficulties driving the bolts to secure the replacement switching unit in the s-zero truss, the agency said, adding they used a long-duration tie-down tether to secure the replacement MBSU to the space station for a future spacewalk.

On Thursday's spacewalk was supposed to last six and half hours but stretched past eight hours.

Prior to this task, Williams was able to successfully connect one of two power cables in preparation for the future arrival of a Russian laboratory module. The third objective, replacing a camera on the Canadarm2 robotic arm was also not completed. This is the fifth spacewalk undertaken by Williams.

Williams along with Hoshide and Yuri Malenchenko of Russia left for the ISS aboard a Russian spacecraft Soyuz TMA-05M on 15 July from the Baikonur cosmodrome in Kazakhstan.

Williams, who was a flight engineer on the station's Expedition 32 crew, became commander of Expedition 33 after reaching the space station.