On November 5, 2026, two astronauts—Anil Menon and Joshua Kutryk—emerged from the International Space Station airlock at 8:36 Eastern Time and returned six hours and fifty-nine minutes later. An ordinary, routine spacewalk. But it was this one that closed out a five-year project: the eighth and final iROSA panel took its place at the far right end of the truss, and the station’s power system, designed in the nineties, was finally brought up to the designed capability of the twenties. Before the upgrade, the original wings put out around 160 kilowatts. Now—around 215. A third of the station’s power appeared in orbit not as a new station, but as eight rolls unfurled over aging panels.
This story matters to me for three reasons. First, it is a rare case of an “upgrade legacy system,” carried out by people in spacesuits, coming in on budget and on schedule without a single failure over five years—and it began, mind you, with an embarrassment. Second, the technology itself—a solar blanket that unrolls like a carpet using the energy of its own elastic booms, without a single motor—is a model of how elegant mechanics beat complexity. And third, it has an unexpectedly compelling lineage: from a startup in Goleta, fattened up on small NASA grants—$850,000 a pop—to panels on the planetary-defense DART mission and the lunar Gateway station. Let’s take it in order.
The ISS’s primary solar wings were designed for a fifteen-year service life. The first pair unfolded back in December 2000, almost immediately after permanent habitation began, and by the start of the twenties they had worked twice as long as planned. Degradation was no surprise; it was a standard page in the documentation: silicon cells burn out under radiation, insulation cracks from temperature swings on every orbit, micrometeoroids leave punctures. Generating strings “fall offline” one after another, as flight director Anthony Vareha put it—and this had been built into power planning for years.
Meanwhile, the station’s appetite only grew: science aboard became more power-hungry, while nobody was planning to write the station off—first the horizon was 2024, then 2028, then 2030. Replacing all eight original wings—sheets measuring 112 by 39 ft—would have been logical, but insanely expensive: effectively new construction right there in orbit. NASA chose another route: not to replace the old, but to cover it with the new.
The ISS Roll-Out Solar Array—iROSA—looks like a challenge to the classical approach. A conventional solar array consists of rigid panels on trusses, deploying through motors, hinges, and all the other mechanics in which every part is a candidate for failure. ROSA, by contrast, is a cylinder when rolled up, and it deploys because two composite booms, twisted during stowage, want to straighten out like springs. No motors. No actuators. Stored strain energy does all the work: an astronaut approaches, cuts the restraining straps, and the blanket unrolls itself along the wing in six to ten minutes.
The elegance here is systemic, not visual. The fewer moving parts, the fewer failure points—and motors and hinges have historically been the chief source of trouble in large arrays. The composite booms also become the structural frame of the unrolled sheet, keeping it from billowing and vibrating. A panel measuring 60 by 20 ft puts out more than 20 kilowatts, while the old tennis-court-sized wing it covers averaged 17–23: both cell efficiency and packing density improved at once.
A rolled-up cylinder is radically more compact than a rigid panel—as the logistics make clear: the panels rode to orbit in the trunk sections of ordinary cargo Dragons, without dedicated flights. The “what if we need to put it away again?” problem is solved just as symmetrically: the old wing folds up, the new one does not, and that is a deliberate tradeoff.
Here one has to honestly tell the story of NASA’s first “live” encounter with ROSA, because it came out funny. In June 2017, a scaled-down prototype was tested on the station’s exterior: the 5.5-meter wing unrolled perfectly, spent a week returning data in sunlight and shadow—and then refused to roll back up. Controllers wrestled with commands for a week, then invoked the prepared Plan B: ROSA was simply released into free flight—jettisoned. The demonstrator panel is still drifting somewhere in orbit as a piece of space debris.
It is easy to laugh in retrospect, though: the prototype did exactly what it had flown to do—it proved that roll-out deployment worked in a real vacuum. And retraction was an option, not a requirement: for the ISS, a one-time deployment is the entire life cycle. The lesson made it into the design: the flight iROSA received more reliable retention hardware. Yet the first spacewalk still did not go smoothly: in June 2021, Shane Kimbrough and Thomas Pesquet went out to install the first full-size panel—and had to end the EVA early because the panel was reluctant to come free from its mounting. Four days later, on June 20, 2021, the second attempt went cleanly, iROSA No. 1 rolled out over the old P6 wing, and from then on the program ran according to plan: CRS-22 (first pair, June 2021), CRS-26 (second pair, November 2022), CRS-28 (third pair, June 2023), and the final fourth pair—panels seven and eight—on CRS-35 in the fall of 2026.
What was done over those five years was also a logistics spectacle. The panels were delivered rolled up in the unpressurized trunk of cargo Dragons, Canadarm2 moved the bundles from the spacecraft to the truss, and after that—only hands: on the final EVA, the 17-meter robotic arm physically could not reach the far end of the right-side truss, so Menon and Kutryk passed the roll to one another in a leapfrog, like a roped climbing team on a wall. And the cherry on top: the final two panels arrived on a single flight, each folded in half to fit inside the trunk.
The bolts and cables, meanwhile, were installed during orbital night—hands in spacesuits cannot touch energized electrical hardware, and in sunlight the panel starts generating power immediately. This spacewalk had its own mini-incident: after sunrise, controllers saw that one of the two still-folded sections was not producing the expected milliwatts. The astronauts waited for the next shadowed orbit, reconnected the cables—and went off to rest, while the deployment proceeded normally: the blanket stretched out to its full 63 ft.
Now for that promised lineage, and this is my favorite part. The technology was born not in a NASA laboratory and not at Boeing. It was conceived by the Goleta, California startup Deployable Space Systems, or DSS (founded in 2008), which lived on SBIR contracts—a program of small innovation grants: Phase I and Phase II in 2009 for a combined “paltry” $850,000, followed by roughly twenty more similar contracts in succession. Then there were NASA’s Game Changing Development and Technology Demonstration Missions programs, which carried the idea from a sheet of paper to a ground prototype and the 2017 flight demonstration. All told, the journey from “crazy idea” to “panel on the ISS” took thirteen years and, by the standards of major space programs, pennies.
Then came the business side: in February 2021, DSS was bought by the aggressively growing Redwire—itself assembled a year earlier out of a chain of startups, from Made In Space to Roccor. DSS became its seventh acquisition; the terms were not disclosed. By the summer of that same year, the first iROSA was operating in orbit, and today ROSA flies on DART (planetary defense, the first asteroid impact in history), on Gateway’s Power and Propulsion Element—where two ROSA wings provide all 60 kilowatts for the lunar station—and on commercial satellites. Redwire’s flysheet lineup runs from the 3.3-kilowatt DIAMOND, weighing 36 kg, to the 37-kilowatt PHENACITE at 521 kg; the ISS wing, SUNSTONE, sits in the middle: 28 kW at 331 kg.
The final panel was not installed for looks: 215 kilowatts is the margin that carries the station through its planned disposal in 2030, supporting every life system, the growing science load, and the docking of new spacecraft. But the real bet is longer-term: iROSA is an operational shakedown of the technology for everything that will fly beyond low Earth orbit. DART has already proven the format on an interplanetary trajectory; Gateway will embed it in lunar infrastructure.
There is bitter irony in this story too. The old creed of space power—“more area, more rigidity, more motors”—was turned upside down by iROSA: a thin blanket, two elastic booms, zero motors, deployment in a matter of minutes. Half the size of the old wing—and more power. “These arrays are amazing: half the size of the old ones and they put out 40% more power,” Menon said after returning to the airlock. Sometimes the best upgrade for a legacy system is not to rewrite everything from scratch, but to carefully wrap what works in a new layer. A patchwork quilt stitched together in orbit over five years—and a station from the nineties gets a power profile from the twenties.
Space digest, November 6: “EVA-101, the final, eighth iROSA panel installed on the ISS; station power rose from 160 to 215 kW.” I checked the NASA blog and CBS News—the digest was accurate, but behind that news line stood a five-year program, the first failure in 2017, the aborted EVA in 2021, and an entire wave of consolidation in the space industry. I put it all together in this note.