Space station power upgrades nearly finished after spacewalk

walking astronauts completed ir part of a three-year power upgre to International Station on Thursday, replacing six more outdated batteries with powerful new ones.

It was third walk in as many weeks involving battery work by NASA's Bob Behnken and Chris Cassidy.

Running more than an hour ahe of schedule, y mand to complete battery swaps in a single walk rar than two. ir fourth walk next week will w focus on or chores.

“Great job,” Mission Control rioed.

Behnken and Cassidy swiftly removed six of remaining old nickel-hydrogen batteries and plugged in three new lithium-ion units.

lithium-ion batteries — big, boxy units with a mass of more than 400 pounds (180 kilograms ) — are so powerful that only half as many are needed. batteries store power gared by station's solar panels for use on nighttime side of Earth.

effort to replace all of station's 48 aging batteries began in January 2017, requiring 11 walks to date.

One new battery shorted out in 2019 and old ones h to be re-installed. One more walk remains, likely this fall. NASA is putting it off inste of tackling it next week because it would involve powering down that power channel.

Besides, two remaining old batteries are working well with all new ones, said Rob Navias, a spokesman at Johnson Center in Houston. “We are fat with power and re is rush,” he said in an email.

NASA expects se new batteries to last rest of station's operational life — ar four years from w at least.

Much of Thursday's six-hour walk unfolded more than 260 miles (420 kilometers) up under bright glare of daylight. “Can't control sun,” Cassidy ted. "Small price to pay for it t going away, I guess. It's nice to be in daylight whole time." Behnken arrived at station at end of May on a X capsule, company's first astronaut flight. He and Doug Hurley are scheduled to return to Earth in Dragon capsule in early August.

Cassidy, station's commander, is halfway through a six-month mission. A Russian Soyuz capsule is his ride to and from orbiting outpost.

Both Behnken and Cassidy each w have nine walks to ir credit.

Im: NASA/AP