Astronauts Mike Hopkins and Victor Glover floated back outside the International Space Station Monday and completed solar array battery replacement work that began four years ago. They also installed three new video cameras and made preparations for upcoming work to install new roll-out solar blankets to upgrade the lab's power system.
The work took less time than expected and the astronauts were able to carry out a variety of lower-priority "get-ahead" tasks before returning to Quest airlock and calling it a day, closing out a five-hour 20-minute spacewalk.
Taking one last look around before entering the airlock, Hopkins said simply, "Beautiful view."
The excursion began at 7:56 a.m. EST when the two men switched their spacesuits to battery power, officially kicking off the 234th spacewalk, or EVA, devoted to station assembly and maintenance since construction began 23 years ago in 1998.
"OK, it's a beautiful day. Let's go for a walk outside," astronaut Bob Hines radioed from mission control in Houston.
The first priority was electrically connecting a replacement battery in the station's solar power system.
The batteries are critical to station operation. They are recharged by the arrays when the lab is in sunlight and then provide that stored power during periods of orbital darkness.
Starting in 2017, spacewalking astronauts began work to replace all 48 of the station's original nickel-hydrogen batteries with 24 smaller, more powerful lithium ion units.
During battery replacement work in March 2019, one of the new lithium ion power packs used by the station's left-side inboard set of arrays failed and was replaced with one of the older nickel hydrogen batteries that had been removed. All of the other older batteries were replaced as planned during multiple spacewalks.
Over the weekend, flight controllers operating the station's robot arm by remote control disconnected the one remaining nickel hydrogen battery and robotically installed a fresh lithium ion unit. Hopkins and Glover electrically connected the battery, finally completing the power system upgrade four years after the work began.
Before leaving the battery worksite, Hopkins and Glover removed a no-longer-needed solar array ground handling fixture to make way for the eventual attachment of new solar blankets to boost the lab's power.
The remainder of the spacewalk was primarily devoted to upgrading the station's external camera system.
With Glover now riding on the end of the station's robot arm, the astronauts first removed and replaced a camera group mounted on a stand attached to the right side inboard solar array truss segment.
Glover then rode the arm to the Destiny laboratory module to attach a high definition camera to an existing set while Hopkins, meanwhile, headed out to the Kibo laboratory module to install a new wrist camera on the lab's small Japanese robot arm.
The astronauts completed their planned work well ahead of schedule, allowing time for a few get-ahead tasks before returning to the airlock and repressurizing at 1:16 p.m. Total spacewalk time across 234 EVAs since station assembly began now stands at 1,471 hours and seven minutes, or 61.3 days.
Two more spacewalks are planned over the next few weeks by the current Expedition 64 crew.
Glover and veteran spacewalker Kate Rubins will work outside the lab to make more preparations for attachment of new solar blankets. Two sets of "ISS roll out solar array" blankets will be carried up later this year aboard SpaceX Dragon cargo ships.
Rubins and Japanese astronaut Soichi Noguchi, also a veteran spacewalker, will carry out a variety of station upgrades during the current crew's final spacewalk.