Spacewalkers begin final phase of a space station upgrade

Key points

• NASA's Anil Menon and the Canadian Space Agency's Joshua Kutryk began a planned six-and-a-half-hour spacewalk at 7:57 a.m. EDT Thursday to install the seventh roll-out solar array on the International Space Station.
• The new arrays are smaller but more efficient than the station's original solar panels, and the final two sets will bring available power to about 215 kilowatts through the lab's planned retirement and de-orbiting in 2030.
• A second spacewalk on Nov. 5 will install the eighth and final array, completing the power system upgrade that began in 2021.

Two astronauts stepped outside the International Space Station on Thursday for the first of two spacewalks, one week apart, to install the final pair of roll-out solar blankets and complete a years-long upgrade of the lab's power system. NASA's Anil Menon and Canadian Space Agency astronaut Joshua Kutryk switched their suits to battery power at 7:57 a.m. EDT, starting a planned six-and-a-half-hour spacewalk, the eighth so far this year and the 285th since ISS assembly began in 1998.

The spacewalk began in orbital darkness, prompting Kutryk to observe that "the night is dark and full of wonders."

Power boost from new arrays

The upgrade began in 2021 with the first of eight ISS roll-out solar arrays, or IROSAs. The IROSAs are smaller than the station's original solar panels but more efficient, using state-of-the-art solar cells. Before the first IROSA was installed, the original arrays generated about 152 kilowatts; the six installed to date have raised that to about 200 kilowatts, and the final two sets will provide some 215 kilowatts to sustain the lab through its planned retirement and de-orbiting in 2030.

The final two IROSAs arrived at the station aboard a SpaceX Cargo Dragon capsule earlier this month, each folded in half and stowed in the ship's unpressurized trunk. The station's robot arm, operated remotely by flight controllers at the Johnson Space Center in Houston, pulled them out and stowed them on the left side of the lab's power truss.

the night is dark and full of wonders

— Joshua Kutryk

Handling the folded arrays

Menon, a veteran of three spacewalks earlier this year, and Kutryk, on his first extra-vehicular activity, planned to install the seventh IROSA on a support fixture at the base of one of the station's left-side inboard solar wings. The flight plan called for unbolting one stowed array so Menon, anchored to the end of the station's 58-foot robot arm, could carry it to its mounting point farther outboard.

Garrett Hehn, a spacewalk flight director, said the folded arrays are around 750 pounds and about 10 feet long, calling it "a lot to handle." He said controllers developed maneuvers to rotate around the arrays' center mass rather than the crew member, a lesson from previous spacewalks. After mounting and unfolding the array, the spacewalkers planned to make electrical connections on Earth's night side and then unroll the blanket, a process Hehn compared to a snap bracelet and said takes about 10 minutes.

Menon and Kutryk plan to float outside again on Nov. 5 to install the final IROSA at the far right end of the power truss, handing it off leapfrog-style because the robot arm cannot reach that far. Gaurang Patel, a senior manager in NASA's Low Earth Orbit Program, said the Nov. 5 work "will essentially complete our power augmentation upgrades."