by Two astronauts ventured outside the International Space Station on Friday and installed the fifth of six deployable solar array blankets — iROSAs — needed to offset age-related degradation and micrometeoroid damage to the lab’s original solar wings.
Floating in the Quest airlock, veteran Stephen Bowen, who was making his ninth spacewalk, and crew member Woody Hoburg, who was making his first, switched their spacesuits to battery power at 9:25 a.m. EDT, officially kicking off the 264th spacewalk dedicated to ISS assembly and maintenance and the seventh so far this year.
NASA is in the process of upgrading the ISS solar power system, adding six iROSAs to the lab’s eight existing U.S. arrays. The first four rollout blankets were installed during spacewalks in 2021 and 2022. Bowen and Hoburg installed the fifth during Friday’s spacewalk and plan to deploy the sixth next Thursday on another excursion.
The two new iROSAs were delivered to the space station earlier this week in the depressurized trunk section of a SpaceX cargo dragon. The lab’s robotic arm pulled them out Wednesday and mounted them on the right side of the station’s powerhouse, just inside the starboard wings.
The astronauts had no problem removing the first 750-pound iROSA from its carrying pallet so that Hoburg, anchored to the end of the robotic arm, could carry it to the installation site. Bowen met him there and they attached it to an already installed mounting fixture.
As the station sailed 260 miles above the Great Lakes, the 20-meter-long solar array slowly unrolled like a full-length sunshade. Well ahead of schedule, the spacewalkers were performing several tasks at the time to get ahead to save time next week when they float back out to install the second new iROSA.
They returned to the airlock and began to repressurize at 3:28 p.m., ending the six-hour, three-minute spacewalk. With nine spacewalks totaling 60 hours and 22 minutes under his belt, Bowen now ranks fifth on the list of the world’s most accomplished spacewalkers.
“I want to congratulate the team on an exceptional EVA. You were fantastic today,” said Canadian astronaut Jenni Sidey-Gibbons, mission control CAPCOM, or radio communicator. “Congratulations to Woody on your first spacewalk and to Steve on your ninth. Finally, congratulations to all of Crew 6 on your 100th day in space. It was a doozy.”
The space station is equipped with four huge solar wings, two on each side of the lab’s power plant. Each wing consists of two 11-meter-wide blankets that extend 35 meters in opposite directions. The first two-decker wing was launched in December 2000 and additional sets were delivered in 2006, 2007 and 2009.
The arrays power eight electrical circuits, two per wing. When the station is in daylight, the arrays charge the batteries and provide power to the lab’s numerous systems. During night passes, the batteries feed stored power to the station.
Solar cells degrade over time, and NASA adds the iROSAs, at a cost of $103 million, to the existing power system to compensate for their reduced output. When fully extended at an angle from the base of an original solar array, each of the new 20-foot-wide rollout arrays can generate more than 20 kilowatts of power.
Combined with the 95-kilowatt output of the original eight panels, the station’s upgraded system will provide approximately 215,000 kilowatts of power. While the iROSAs cast shadows on the underlying arrays of original equipment, the combined output will exceed what the older wings generated when they were new.
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