Astronaut Peggy Whitson (center) helps spacewalkers Thomas Pesquet (left) and Shane Kimbrough suit up before beginning their spacewalk Jan 13, 2017. [Photo/Xinhua]

It was Whitson's eighth spacewalk, making her surpass the previous the record of seven set by another US astronaut Sunita Williams.

Whitson, 57, now also has the most cumulative spacewalking time, beating Williams's record of 50 hours and 40 minutes.

During Thursday's spacewalk, Whitson and her fellow astronaut Shane Kimbrough successfully connected cables at a structure called Pressurized Mating Adapter-3 (PMA-3), which was just recently robotically relocated from the station's Tranquility module to the Harmony module.

The duo were also tasked with installing four thermal protection shields to cover the spot on the Tranquility module where the PMA-3 was removed, but one of the shields was "inadvertently lost" during the spacewalk, NASA said.

"The loss posed no immediate danger to the astronauts and Kimbrough and Whitson went on to successfully install the remaining shields on the common berthing mechanism port," it said in a statement.

The space agency noted the two astronauts finally finished covering the spot with a PMA-3 cover they removed earlier in the day.

"The plan worked, and the cover was successfully installed, providing thermal protection and micrometeoroid and orbital debris cover for the port," it added.

Thursday's spacewalk, which lasted just over seven hours, was the second in a series of three spacewalks to prepare the station for future installation of a new docking port called International Docking Adapter (IDA), which will accommodate commercial crew vehicle dockings.

The space station already has one IDA, and the second will be delivered on a future SpaceX Dragon cargo mission.

The first of three spacewalks was performed one week ago, while the third and final one is slated for April 6.