Two American astronauts took a spacewalk Friday to replace aging batteries on the International Space Station.
NASA's Anne McClain and Nick Hague were scheduled to work in space Friday for several hours to swap out three old nickel-hydrogen batteries with more powerful lithium-ion batteries.
The station's robotic arm did much of the heavy work already, but the astronauts still have to lug 300-pound adaptors the size of a large coffee table and reconnect attachments.
Even when the chore is complete, there will still be more of the 20-year-old station's original batteries to replace.
McClain and Hague finished the job in about 6 hours and 20 minutes.
Friday's spacewalk was the first of three planned excursions to replace batteries and perform other maintenance. Next week's spacewalk will include the first all-female crew, including McClain.