U.S., French Astronauts Complete Spacewalk To Upgrade ISS Power System

French astronaut Thomas Pesquet is pictured on his first spacewalk, outside the International Space Station on January 13.

A pair of astronauts on January 13 successfully completed a six-hour spacewalk outside the International Space Station (ISS), plugging in modern new batteries for use by the craft's solar power system.

ISS Commander Shane Kimbrough of the United States and French astronaut Thomas Pesquet attached three new lithium-ion batteries, adding to the three hooked up last week by Kimbrough and astronaut Peggy Whitson during a spacewalk.

Russian cosmonauts Andrei Borisenko, Sergei Ryzhikov, and Oleg Novitsky are also part of the six-member ISS crew.

NASA said the lithium-ion batteries were important upgrades to the space station's solar power system. The new batteries provide improved power capacity with a lighter mass and a smaller volume than previous nickel-hydrogen batteries.

Along with the six currently installed, 18 more need to be plugged in over the next two to three years, with the next batch scheduled for late this year or early 2018, NASA says.

Kimbrough and Pesquet finished the battery work within about three hours of the spacewalk and spent three more hours performing other tasks before re-entering the ISS. It was the fourth career spacewalk for Kimbrough and Pesquet's first.

The walk was completed at 12:20 ET, with NASA tweeting "We did it!" and publishing video and photos on its Twitter feed and website. In a statement, the space agency described the spacewalk as "very successful." Twitter feed:

NASA said the three Russian cosmonauts were focusing on research and lab-maintenance duties.

Borisenko and Novitsky collected blood samples for research on possible stress and bone loss caused by living in space. Rookie cosmonaut Ryzhikov is studying chemical reactions caused by jet-engine exhaust in the Earth's upper atmosphere, NASA said.

With reporting by AP and AFP