In second attempt, spacewalkers successfully deploy balky solar array
Spacewalkers Thomas Pesquet and Shane Kimbrough successfully deployed a balky roll-out solar blanket on the International Space Station Sunday after problems derailed an attempt last week.
"Beautiful," Pesquet, a European Space Agency astronaut, marveled after releasing a final bolt, watching as the 15-foot-wide array began unfurling on the far left end of the station's solar power truss.
Unrolling like a carpet with the pent-up "strain energy" in two compressed carbon composite struts, it took about six minutes for the ISS roll-out solar array — iROSA — to unwind a full 60 feet in front of the station's far left port 6, or P6, solar wing.
"Good news, you two," Canadian astronaut Jenni Sidey radioed from mission control in Houston. "We're tracking a full and good deploy of that solar array."
The 60-foot-long roll out solar arrays have successfully deployed as the space station soared over the United States. #AskNASA | https://t.co/yuOTrYN8CV pic.twitter.com/6mQOQ2Fj5n
— International Space Station (@Space_Station) June 20, 2021
The new array, the first of six being added to the station in a major upgrade, was electrically tied into power channel 2B, one of the lab's eight major circuits, providing about 20 kilowatts of power.
The iROSA blankets are intended to offset age-related degradation of the lab's original eight solar wings, boosting overall power output back to factory-fresh settings.
The new arrays are not replacing the originals. Rather, they were designed to be mounted adjacent to six of the original eight wings, tilted out about 10 degrees. While the new panels will shade a large portion of the underlying solar cells, their combined output will equal or exceed the original's when it was new.
The successful installation of the first iROSA clears the way for Pesquet and Kimbrough to venture back outside the station Friday to install a second roll-out blanket on the P6 truss segment, this one feeding electricity into power channel 4B.
NASA originally planned to install that panel Sunday. But during a spacewalk Wednesday, Pesquet and Kimbrough ran into problems, first with Kimbrough's spacesuit and then with an interference issue that prevented them from unfolding and aligning the new array so it could be deployed.
Kimbrough wore a different spacesuit Sunday and the astronauts were able to manually adjust the alignment of the iROSA, allowing them to lock the structure in place as required. They then waited for orbital darkness to electrically connect the blanket before proceeding with its deployment.
Before calling it a day, the astronauts made initial preparations to remove the second iROSA from its storage platform so it can be moved out to the P6 truss for installation on Friday.
Sunday's spacewalk began at 7:42 a.m. EDT and ended 6 hours and 28 minutes later. It was the eighth spacewalk outside the International Space Station so far this year, the 240th in station history, the fourth for Pesquet and the eighth for Kimbrough.
Kimbrough has now logged 52 hours and 43 minutes working in the vacuum of space over three missions, moving him up to 11th on the list of most experienced spacewalkers. Friday's planned excursion should move him into the top 10.