NASA nears end of space station solar array upgrade with Oct. 29 and Nov. 5 spacewalks

NASA is two spacewalks away from completing a major, years-long upgrade to the International Space Station that will power the orbiting lab through to its planned decommissioning in 2030.

More than five years after the upgrade work first began in earnest, NASA astronaut Anil Menon, 43, and Canadian Space Agency astronaut Joshua Kutryk, 44, are scheduled to depart the station’s Quest airlock at 8 a.m. EDT (1200 UTC) Thursday to install and unfurl the seventh of eight International Space Station Roll-Out Solar Arrays, or IROSAs.

The compact, high-efficiency panels are designed to make up for power lost as the station’s original solar wings have degraded over more than two decades in orbit. Spaceflight Now will carry live coverage of the spacewalk starting at 6:30 a.m. EDT (1030 UTC).

If all goes to plan, Menon and Kutryk will venture back into the vacuum of space Nov. 5 to install the eighth and final array, capping an upgrade campaign that began in 2021. NASA says the eight IROSA arrays will raise the station’s available power from 160 kilowatts to about 215 kilowatts, supporting critical operations through the outpost’s final years, including its “safe and controlled deorbit” after it is retired in 2030.

“Overall, these roll-out arrays increase our power generation capability up to 30 percent,” Gaurang Patel, operations integration manager for NASA’s Low Earth Orbit Program, said during an Oct. 20 briefing at the Johnson Space Center in Houston.

Thursday’s outing, which marks the 285th spacewalk devoted to station assembly, maintenance and upgrades, is planned to last about six hours and 45 minutes. It will be Menon’s fourth excursion outside the ISS airlock and the first for Kutryk. During Thursday’s spacewalk and on Nov. 5, Menon is scheduled to perform a series of complex maneuvers atop to the station’s robotic arm to transport the final IROSA arrays into position for roll out.

Menon, a U.S. Air Force lieutenant colonel and emergency physician, has made his three prior spacewalks since July when he arrived at the ISS aboard a Russian Soyuz.
Kutryk, a Royal Canadian Air Force colonel and test pilot who boarded the ISS Oct. 1 as part of SpaceX’s Crew-13 mission, will become the fifth Canadian astronaut to walk in space and the first since David Saint-Jacques in 2019.

The pair of final IROSA solar wings arrived at the station rolled up and folded on a carrier in the unpressurized trunk of a SpaceX Cargo Dragon capsule after receiving a boost to orbit from a Falcon 9 rocket launched Oct. 13 from the Cape Canaveral Space Force Station. Each IROSA assembly weighs about 750 pounds, said Garrett Hehn, the spacewalk flight director, who is leading the operation with flight director Greg Whitney.

After Menon and Kutryk free the first array from the carrier Thursday, Menon will lock his boots into a foot restraint on the end of the station’s Canadian-made robotic arm — Canadarm2 — and ride it, array in hand, out to the left, or port, side of the station’s main truss. NASA astronauts Jessica Watkins and Luke Delaney will fly the arm from inside the station while Kutryk makes his way to the installation site along the truss.

While in transit, the arm will pivot around the IROSA assembly’s center of mass, rather than Menon’s, one direction at a time — a lesson learned from earlier installs meant to make the work “a little less tiring” for the astronaut holding it, Hehn said.

While the rolled up array is weightless in space, it still carries 750 pounds of inertia.

Once the IROSA is bolted to an awaiting mounting bracket astronauts installed during a March spacewalk, Menon and Kutryk will swing it open, doubling its length from about 10 feet to 20 feet. Hehn called that step “one of our key points of the EVA,” or extravehicular activity.

Menon and Kutryk then must lock the two halves in place and connect the new array’s power cables to the station while it’s in Earth’s shadow, when none of its solar panels are generating electricity.

“We can’t have any sun on the arrays whenever we’re handling those hot cables,” Hehn explained.

Finally, the astronauts will release the last restraints and let the IROSA array unroll on its own over about 10 minutes — no motors required — thanks to energy stored in carbon-fiber composite booms. Hehn likened the panels to a snap bracelet that, once released, “just continues rolling out steadily.”

Space shuttles delivered the station’s eight original solar wings, which were designed to last 15 years, between 2000 and 2009. Rather than replacing them outright, NASA opted to mount the smaller IROSA arrays, which generate about 8 kilowatts of electricity each, in front of the old wings, allowing the original panels’ unshaded portions to keep producing power.

The first IROSA unfurled in June 2021, though not without a fight: A spacesuit glitch and an array that wouldn’t unfold cleanly forced astronauts Shane Kimbrough and Thomas Pesquet to finish the job on a second spacewalk. Six arrays were in place by June 2023, and NASA ordered an additional pair that summer.

The Nov. 5 spacewalk will take the eighth and final array to the far right end of the station’s main truss, beyond the reach of its robotic arm. As during Thursday’s EVA, Menon will ferry the array atop the robotic arm as far as it will take him, but to cover the last stretch, he and Kutryk will pass the array between foot restraints in a maneuver Hehn said the team “lovingly” calls “the leapfrog.”

As with all spacewalks, the work carries risk. NASA’s spacesuits date to a design first flown in 1983 and are responsible for providing critical life support in the harsh environment of low earth orbit, where temperatures fluctuate between 250 degrees Fahrenheit in sunlight to minus 250 degrees in darkness during each 90-minute orbit.

A NASA inspector general audit last year flagged aging hardware and thin supplies of spare-parts as potential safety weak spots.

Collisions between a spacewalking astronaut and space debris as small as a grain of sand can prove “life threatening,” according to NASA, due to the sheer speeds involved: The ISS and the astronauts orbiting the Earth with it are already traveling at about 17,500 mph, and collisions with space debris in low earth orbit average about 22,000 mph, or 10 kilometers per second, according to NASA’s White Sands Test Facility.

Hehn said Oct. 20 that the suits are “not entirely redundant” and acknowledged they are aging, “which means we know they have some quirks.”

“Our primary goal is to keep the crew safe,” he said.