Smaller Wings, Similar Output

Two astronauts are set to step outside the International Space Station on Thursday, Nov. 5, to install the last of eight flexible roll-out solar arrays. The job will complete a five-year effort to restore power lost as the station's original solar wings aged.

NASA astronaut Anil Menon and Canadian Space Agency astronaut Joshua Kutryk plan to begin the spacewalk at 8:30 a.m. EST, according to a NASA station update revised Nov. 2. NASA+ coverage is scheduled to start at 7 a.m. EST, and the work is expected to take about seven hours.

When it is done, NASA says the station's power-generating capacity will rise about 30%, from 160 kilowatts to about 215 kilowatts. That extra electricity supports research now and, according to NASA, critical operations through the station's final years, including a safe and controlled deorbit.

The new hardware is a striking example of how far solar technology has come. Each International Space Station Roll-Out Solar Array, or IROSA, measures about 60 feet long by 20 feet wide. The original wings measure 112 feet long by 39 feet wide, roughly twice as long and twice as wide.

Despite their smaller size, each new array produces more than 20 kilowatts in orbital daylight, according to NASA, while the original arrays generate an average of 17 to 23 kilowatts each. Lighter, more efficient solar cells and a thin, flexible blanket design deliver comparable power from a much smaller footprint.

The arrays launch rolled up like a carpet. Once mounted, they unroll on their own, using energy stored in flexible composite booms, much like a tape measure extending from its case. The design was first tested outside the station in 2017.

Two Decades of Wear on the Original Arrays

The station's original solar wings were designed for a 15-year service life. The first pair was deployed in December 2000, with more added in 2006, 2007, and 2009, according to NASA.

Constant exposure to the space environment gradually degrades solar cells. Harsh radiation, extreme temperature swings as the station passes from sunlight to shadow every orbit, and impacts from tiny debris all take a toll. NASA has said the original arrays are functioning well but have shown expected degradation after operating beyond their design life.

Rather than replace the giant wings, engineers chose to mount the new arrays in front of six of them — angled slightly above — an approach that reuses existing sun-tracking joints and power systems. The tradeoff is that each new array shades part of the old wing behind it, so the net gain per array is smaller than its full output.

Six IROSAs were installed from 2021 to 2023. The final pair arrived on a SpaceX cargo Dragon this fall.

Power for the Station's Final Years

The upgrade is no longer just about expanding science. NASA plans to retire the station in 2030, Spaceflight Now reported, and reliable power is essential for steering an outpost the size of a football field safely out of orbit.

"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 at an Oct. 20 briefing.

On Earth, the same technology lesson applies to rooftop and utility-scale solar. Panels lose a small amount of output each year, and long-lived systems eventually need augmentation or replacement. The station shows how adding newer, more efficient panels to aging infrastructure can restore capacity without tearing everything down.

The seventh array went up on Oct. 29. Menon and Kutryk spent 7 hours and 11 minutes outside, installing it on the station's 2A power channel and finishing at 3:08 p.m. EDT, NASA reported. It was the 100th U.S. spacewalk from the station, Menon's fourth and Kutryk's first.

The pair connected power cables while the station was in Earth's shadow, a safety step. "We can't have any sun on the arrays whenever we're handling those hot cables," spacewalk flight director Garrett Hehn explained before the work.

Thursday's Leapfrog Spacewalk

The final array, destined for the 3B power channel, poses a different challenge. Its mounting site sits at the far right end of the station's main truss, beyond the reach of the Canadarm2 robotic arm.

Menon will ride the arm carrying the rolled-up array as far as it can reach. The two astronauts will then pass the array between foot restraints in a maneuver the team calls the "leapfrog," Spaceflight Now reported. Inside the station, NASA astronauts Jessica Watkins and Luke Delaney will operate the robotic arm.

During the Oct. 29 excursion, the pair completed several get-ahead tasks to prepare the final array. If Thursday goes as planned, it will be the 101st U.S. spacewalk and the 286th in support of station assembly and maintenance.

Spacewalk times can shift. NASA already revised the start time once this week, so viewers should check the NASA+ schedule on Thursday morning. Weather on Earth has no effect, but technical issues or crew readiness can delay the work.

What remains uncertain is how the station will spend its last years and exactly how the deorbit will unfold. What is clear is that the power system the station relies on will be fully upgraded by the end of this week if all goes to plan.

The bottom line is that eight compact, flexible solar arrays are restoring the station's electricity to about the level it had when the original wings were new. The final installation is scheduled for 8:30 a.m. EST Thursday, and NASA will confirm the station's new power capacity after the array unrolls.

What Readers Want to Know

What is happening on Nov. 5? Astronauts Anil Menon and Joshua Kutryk plan a spacewalk starting at 8:30 a.m. EST to install the eighth and final roll-out solar array on the space station.

How much power will the station gain? NASA says capacity will rise about 30%, from 160 kilowatts to about 215 kilowatts.

How can smaller arrays produce similar power? The roll-out arrays use more efficient solar cells on a thin, flexible blanket. Each produces more than 20 kilowatts, comparable to the original wings, which are roughly twice as long and twice as wide.

Why did the original arrays need help? They were designed for 15 years of service and have been operating since as early as 2000. Radiation, temperature swings, and debris gradually degrade solar cells.

What does this have to do with the deorbit? NASA says the extra power supports critical operations through the station's final years, including a safe and controlled deorbit. NASA plans to retire the station in 2030.

Where can I watch the spacewalk? NASA+ coverage is scheduled to begin at 7 a.m. EST on Nov. 5. Times can change, so check NASA's schedule Thursday morning.