Astronauts from the U.S. space shuttle Atlantis finished installing a new six-pack of batteries on the International Space Station Friday during the third and final spacewalk of their mission.
The six large batteries aboard the station, each weighing 170 kilograms, cost $22 million. With shuttle flights scheduled to end later this year, the U.S. space agency wanted to complete replacement of the station's 10-year-old battery system to ensure the orbiting laboratory can remain in service until at least 2020, as planned.
The nickel-hydride batteries, each about one meter-wide, store energy collected by the space station's wing-shaped solar panels. The batteries distribute power during the portion of each orbit when sunlight disappears as the station travels behind the Earth.
The U.S. space agency says astronauts Michael Good and Garrett Reisman completed work on the battery installation, which began Wednesday early in Friday's spacewalk. They also installed a dish-shaped antenna and attached a new Russian-built compartment to the space station, a modular structure that has been assembled gradually during years of shuttle missions.
The 25-year-old shuttle Atlantis, due for retirement after this weeklong mission, will undock from the station for the final time on Sunday.
The shuttle arrived at the orbiting outpost last Sunday. NASA will use other space shuttles for two more missions due to take place later this year. That will mark the end of the space-shuttle program.
Future visitors to the International Space Station will travel into orbit aboard Russian rockets, or possibly privately operated spacecraft, to take part in research and deliver supplies.
Some information for this report was provided by AFP and AP.