Indian American astronaut Sunita Williams and US spacewalking record-holder Michael Lopez-Alegria have wound up a six-hour, 40-minute spacewalk, the last in an unprecedented series of three spacewalks in nine days from the quest airlock.

While, astronaut Michael Lopez-Alegria broke the US record of most time walking in space, he needs more than 24 hours to beat the all-time record (82 hours) of Russian Anatoly Solovyov.

Sunita, in her all white space suit and lopez-alegria donning red striped suit, accomplished all their primary tasks of maintenance work outside the international space station, successfully on Thursday.

The major tasks scheduled for Thursday's spacewalk included the removal and disposal of several unneeded thermal shrouds, the deployment of an ISS cargo carrier attachment point, loosing several launch locks on the station's portside truss, and the successful installation of a set of cables to transfer power from the ISS to visiting space shuttles.

In addition to the mentioned tasks, they were also able to perform an extra photo survey of the station's shuttle docking port, known as the Pressurized Mating Adapter-2. It was the last in an unprecedented series of three spacewalks in nine days from the quest airlock.

The three spacewalks, termed EVAs 6, 7, and 8 because there were five previous station spacewalks from the US airlock quest during increments, times when no shuttle was present, began Thursday at 7:27 CST (18:57 IST).

NASA's STS-118 shuttle mission, set to launch this June, is slated to be the first mission to make use of the new power transfer system.

Lopez-Alegria now holds the second place for the most spacewalk time -- 58 hours and 32 minutes -- by an American astronaut. He surpassed NASA astronaut Jerry Ross to take the US title, barely after four hours of spacewalk.

Sunita has already set her own spacewalking record, by surpassing NASA astronaut Kathryn Thornton as the most experienced female spacewalker of all time on Sunday with three EVAs and 22 hours, 37 minutes of work outside a spacecraft.

This spacewalk marked the 80th EVA dedicated to the ISS assembly or maintenance, and push total spacewalking time outside the orbital laboratory past the 490-hour mark at full duration.

The three spacewalks, from the Quest airlock in US spacesuits, and a Russian spacewalk scheduled for February 22 will be the most ever done by station crew members during an increment, said Mike Suffredini, station program manager.

On February 22, Lopez-Alegria and Tyurin are scheduled to do a spacewalk in Russian Orlan suits from the Pirs airlock. They will work on an antenna of the Progress 23 unpiloted cargo carrier, docked at the aft port of the Zvezda service module.