The International Space Station's long power upgrade is done, and it finished the way a lot of good jobs do: with a minor problem and a bit of waiting around.
NASA astronaut Anil Menon and Canadian Space Agency astronaut Joshua Kutryk installed and deployed the eighth and final International Space Station Roll-Out Solar Array, or iROSA, during a spacewalk on November 5. NASA says the array went on the 3B power channel and that the six-hour, 59-minute spacewalk completed the station's power augmentation upgrades.
"We got it done!" Menon said at the end, according to Space.com.
The snag
The last deployment was briefly held up. Space.com reports that the pair retrieved the 750-pound (340 kg) assembly from a temporary stowage platform, carried it to the worksite on the Canadarm2 robotic arm and mounted it to a bracket kit already in place. Then Menon connected the cables, and the numbers came back wrong.
"We are seeing half of the expected shunt current that we want," spacewalk officer Nichole Stilwell radioed from Mission Control, Space.com reports. "In this current config, we are not necessarily going to deploy."
The connectors needed inspecting, but not straight away. Solar arrays generate electricity whenever the sun is on them, so Space.com says the astronauts had to wait for the station to pass into Earth's shadow before anyone could safely look. They spent the time tidying the worksite and parking the robotic arm. The issue cleared, and Stilwell came back with a go for deployment.
Then came the part that needs no help at all. After two bolts were released, the array unrolled to its full 63 feet (19 metres) on the stored energy of its rolled carbon composite booms, with no motor involved. Space.com says the whole thing took about 10 minutes.
What the upgrade adds
NASA says work on the upgrade began in February 2021, and that astronauts have since completed 18 spacewalks to prepare power channel equipment and install the eight arrays. Together, NASA says, the roll-out arrays raise the station's power generation capacity from 160 kilowatts to about 215 kilowatts.
By our arithmetic, that's a rise of roughly a third. Other figures are floating around: Space.com says the new arrays let the old wings produce as much as 30% more electricity, while Menon said at the close of the spacewalk that they were "half the size of the old ones and bringing 40% more power." The kilowatt figures are the ones to hold on to, since they're the agency's stated capacity for the station as a whole.
The reason for all this is ageing hardware. Space.com reports that flight controllers saw the station's eight original arrays losing output as they passed their 15-year design life. The iROSAs augment those legacy wings, and they're meant to supply the power the station needs until its retirement and controlled deorbit, currently scheduled for late 2030.
The numbers
NASA counts this as the 286th spacewalk in support of station assembly, maintenance and upgrades. Space.com adds that it was the ninth spacewalk of 2026 and the sixth by the station's current crew, Expedition 75.
Stilwell's sign-off, as reported by Space.com, noted that the station had just passed 26 years of constant human presence. She told the pair they had shown what the best of humanity looks like while "making it look easy."
Finn's take: I like that the last job on an upgrade running since 2021 came down to waiting for the sun to go away. A station with four years left on the clock is still being looked after properly, and the best bit of the day was a machine with no motor doing exactly what it was told.
Reporting notes
