Spacewalkers fit the seventh roll-out solar array to the space station
NASA says the new arrays will lift the station's power generation from 160 kW to about 215 kW. The eighth and last is due on 5 November.
Two astronauts spent 7 hours and 11 minutes outside the International Space Station on 29 October and installed the seventh of eight new roll-out solar arrays. NASA says the set will raise the station's power generation capacity from 160 kilowatts to about 215 kilowatts, and increase available power by up to 30%. The eighth and last array is scheduled for a spacewalk on Thursday 5 November. The walk was the 100th spacewalk by US astronauts.
- 160 → 215 kWstation power generation capacity before and after the new arrays
- up to 30%increase in available power NASA expects from the eight arrays
- 7 h 11 minlength of the 29 October spacewalk
What happened on the spacewalk
NASA astronaut Anil Menon, on his fourth spacewalk, and Canadian Space Agency astronaut Joshua Kutryk, on his first, installed the array on the station's truss. NASA lists it as the seventh ISS Roll-Out Solar Array, or IROSA, and connected it to the power channel the station calls 2A.
The walk ended at 3:08 p.m. US Eastern time. NASA counts it as the 285th spacewalk in support of station assembly, maintenance and upgrades. The station orbits about 260 miles, roughly 420 kilometres, above Earth.
The next spacewalk, planned for 5 November, is meant to install the eighth and final IROSA on the 3B power channel. NASA says it will carry the event live. As with any spacewalk, the date can move for technical or safety reasons.
Why the station needs new arrays
The station's original solar arrays were installed in stages from 2000. Solar cells in orbit degrade, because radiation, thermal cycling between sunlight and shadow, and small debris impacts all wear them down. An array that loses output every year still has to power a laboratory that keeps adding equipment.
Rather than remove the old arrays, the roll-out arrays are mounted in front of part of them. Each new array shades a portion of the older one beneath it, so the gain is not simply the new array's rating added to the old total. That is why NASA expresses the benefit as a rise in total capacity and in available power, not as a sum of panels.
The approach is a form of repowering, which power engineers on Earth use for old wind farms and solar plants: keep the structure and connections, replace the generating element, and avoid a full rebuild.
How a roll-out solar array works
A roll-out array is stored as a compact cylinder. Once mounted, it unrolls under the stored energy of its own flexible composite booms, which straighten as they deploy and pull a thin blanket of solar cells flat. No motor drives the unrolling. The design trades mechanical complexity for stored elastic energy.
The advantage is mass and volume. Rigid folding panels need heavy hinges and frames. A rolled blanket fits a smaller launch package and weighs less for the power it delivers, which matters when every kilogram has to be lifted into orbit.
The trade-off is that a flexible blanket must stay flat and tensioned to point at the Sun correctly, and its cells must survive many years of temperature swings. Engineers test the deployment many times on the ground in conditions designed to imitate weightlessness before trusting it in orbit.
Power on a station is a grid problem
The station is a small, isolated grid. It generates during the sunlit part of each orbit, about 90 minutes long, and runs on batteries through the dark part. Arrays, batteries, voltage regulators and distribution switches have to be sized for the peak load in darkness, not just the average in sunlight.
Power is split into separate channels, labelled such as 2A and 3B, so that a fault in one does not black out the station. Adding generation to a channel means checking the rest of that channel can carry it. The array is the visible part of the upgrade; the wiring and controls behind it are where reliability is decided.
That design logic matches a hydropower-heavy grid on Earth. Generation varies, storage is limited, and loads have to be protected by splitting the system into sections with their own switching.
Why it matters to engineering students in Nepal
Nepal's grid is not in orbit, but its engineers face versions of the same questions: how to add generation to an ageing network, how to keep sections isolated when one fails, and how to plan for seasons when output drops. In Nepal the dry season does to run-of-river hydropower what orbital night does to a solar array.
Rooftop and ground solar are spreading in Nepal, and the cell physics is the same as in space. Students who understand degradation, temperature effects and the difference between nameplate and delivered power will design better installations at home.
The space station is also an example of maintaining a system for decades rather than replacing it. Most engineering work in Nepal is of that kind: keeping roads, lines and plants working longer than their designers planned, with upgrades fitted around live operation.
What to study if this interests you
Electrical and electronics fundamentals cover how solar cells, converters and batteries behave. Power electronics explains the converters that turn variable solar output into regulated buses. Communication and control courses explain how a system like the station monitors and switches its own power channels.
A useful student project is to log a small solar panel's output over several weeks and compare it with its rating. Measure the effect of temperature, shade and dust. The gap between the label and the meter is the same gap NASA manages on a much larger scale.
Read the NASA blog post linked below for the mission details. When the eighth array is installed, compare NASA's reported figures with the ones here. Checking a forecast against what was delivered is a good engineering habit.
Words in this story
- IROSA
- ISS Roll-Out Solar Array, a flexible solar blanket that unrolls on composite booms, mounted in front of the station's original arrays.
- Spacewalk
- Work done by astronauts in spacesuits outside a spacecraft, also called extravehicular activity.
- Power channel
- One of the station's separate electrical circuits, each with its own generation, storage and distribution.
Where this comes from
- NASA, 29 Oct 2026
Written in our own words; no sentence is copied from these reports. Researched with AI assistance and added 17 October 2026; no member of faculty has reviewed this story yet. If you spot a mistake, call 01-5091616 and we will correct it and say so.