Astronauts aboard China's Tiangong space station performed the orbiting facility's second spacewalk for repairs on Saturday in an eight-hour mission to finish fixing damaged solar panels.
Astronauts Tang Hongbo and Jiang Xinlin left the station and used a robotic arm mounted on the outside of the facility to repair the panels on the Tianhe core module, the China Manned Space Agency said.
Tang Shengjie, the third member of the Shenzhou 17 crew, stayed on board and coordinated with scientists on Earth to help control the robotic arm.
"This is the first time that Chinese astronauts have completed the maintenance of extravehicular facilities of an orbiting spacecraft," the agency said on Saturday.
Astronauts Tang Hongbo and Jiang returned safely to the Wentian experimental lab module, it said.
During the repair mission, the astronauts also inspected the station's surface.
The Shenzhou 17 crew conducted their first extravehicular maintenance mission on December 21, when they began the task of repairing the panels.
That exercise took about 7½ hours.
After the spacewalk on Saturday, power from the solar panels was "normal".
The Tiangong's flexible solar panels, which are on the Tianhe and the Wentian and Mengtian experimental modules, power the station.
Before the crew lifted off in October, agency deputy director Lin Xiqiang said the station's solar panels had suffered minor damage from small, flying space debris.
The agency had announced plans for the spacewalk on Friday, saying the crew had inspected their spacesuits and station equipment.
Since their mission in December, the crew had practised operating the robotic arm, as well as familiarised themselves with various safety and debugging procedures, the agency said.
The Shenzhou 17 crew are scheduled to return to Earth in April after handing over control of the station to the Shenzhou 18 crew, whose members and departure date have not been announced.
In their time left on the Tiangong, the Shenzhou 17 crew will continue to conduct planned scientific experiments in fields including life sciences and microgravity.