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NASA upgrades the International Space Station's aging power grid with new roll-out solar arrays

NASA upgrades the International Space Station's aging power grid with new roll-out solar arrays

Built World

A five-year effort to restore the station's electricity supply enters its final phase as astronauts prepare the last two power channels

March 18th, 2026: First spacewalk preps 2A power channel for final arrays

Overview

The International Space Station's original solar arrays were designed to last 15 years. The oldest set has now been in orbit for 25, battered by radiation and micrometeorite strikes until the station's total power output dropped from 240 kilowatts to roughly 160 — a one-third loss. On March 18, 2026, astronauts Jessica Meir and Chris Williams stepped outside for a 6.5-hour spacewalk to prepare the final two power channels for new roll-out solar arrays that will restore the station's capacity.

The upgrade matters because the station needs full power to keep running through 2030, when NASA plans a controlled deorbit. Six of the eight new arrays are already installed, collectively generating over 120 kilowatts of fresh capacity. The March spacewalk — the 278th supporting station assembly — routed cables and bolted down mounting hardware on the 2A power channel.

A second spacewalk will prepare the 3B channel. Once the final two arrays arrive aboard a SpaceX cargo Dragon and are installed, the station's full eight-channel power grid will be restored to near-original output for the first time in over a decade.

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Key Indicators

6 of 8
New arrays installed
Six ISS Roll-Out Solar Arrays have been installed since 2021, with the final two in preparation.
~160 kW
Degraded power output before upgrades
The station's original arrays had lost roughly one-third of their generating capacity due to 25 years of space exposure.
278th
Station assembly spacewalk
The March 18 spacewalk marks the 278th extravehicular activity supporting ISS construction and maintenance.
25 years
Age of oldest solar arrays
The P6 truss arrays, installed in December 2000, have operated a decade beyond their 15-year design life.

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People Involved

Jessica Meir
Jessica Meir
Aboard the ISS on Expedition 74
 Chris Williams
Chris Williams
Aboard the ISS on Expedition 74
 Michael Fincke
Michael Fincke
Returned to Earth after medical evacuation in January 2026

Organizations Involved

National Aeronautics and Space Administration (NASA)
National Aeronautics and Space Administration (NASA)
Federal space agency
ISS operator and program lead for solar array upgrades

The United States space agency responsible for operating the American segment of the International Space Station and managing its power infrastructure upgrades.
Redwire Space
Redwire Space
Aerospace Manufacturer
Primary manufacturer of IROSA arrays

The space infrastructure company that designs and manufactures the roll-out solar arrays under contract with Boeing, the station's prime contractor.

Timeline

December 2000 March 2026

8 events Latest: March 18th, 2026 · 4 months ago
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  1. First spacewalk preps 2A power channel for final arrays

    Latest Spacewalk

    Meir and Williams spent 6.5 hours outside the station routing cables and installing a modification kit on the P4 truss to prepare power channel 2A for its new roll-out solar array. It was the 278th ISS assembly spacewalk and Williams' first-ever extravehicular activity.

  2. Crew-12 arrives to take over spacewalk duties

    Mission

    Jessica Meir and her Crew-12 teammates launched aboard a SpaceX Dragon, inheriting the solar array spacewalk assignments from the evacuated Crew-11.

  3. Spacewalk postponed after astronaut medical event

    Delay

    Crew-11 Commander Mike Fincke experienced a medical event the day before the scheduled solar array spacewalk, triggering the first medical evacuation in the station's 25-year history. All four Crew-11 members returned to Earth on January 15.

  4. Third IROSA pair completes initial six-array upgrade

    Installation

    Steve Bowen and Warren Hoburg installed the third pair on channels 1A and 1B, finishing the initial contract. NASA had already signed a $35 million deal for a fourth pair to complete all eight channels.

  5. Second IROSA pair installed on S4 and P4 trusses

    Installation

    Astronauts Josh Cassada and Frank Rubio installed arrays on power channels 3A and 4A, extending the upgrade to four of the station's eight power channels.

  6. First IROSA pair installed on P6 truss

    Installation

    Astronauts Shane Kimbrough and Thomas Pesquet installed the first two roll-out arrays on power channels 2B and 4B over three spacewalks, beginning the station's power restoration.

  7. Roll-out solar array technology demonstrated on ISS

    Technology

    NASA tested the Roll-Out Solar Array concept on the station as a technology demonstration, proving the compact, lightweight design could work in orbit.

  8. First ISS solar arrays deployed

    Infrastructure

    The first pair of Solar Array Wings was deployed on the P6 truss segment, beginning the station's power system buildout. All eight original arrays were installed by March 2009.

Historical Context

2 moments from history that rhyme with this story — and how they unfolded.

December 1993 – May 2009

Hubble Space Telescope servicing missions (1993–2009)

NASA conducted five Space Shuttle missions to repair and upgrade the Hubble Space Telescope, replacing degraded solar arrays, gyroscopes, and scientific instruments. The first mission in 1993 famously corrected Hubble's flawed primary mirror with a set of corrective optics, transforming it from an embarrassing failure into the most productive telescope in history.

Then

Each servicing mission extended Hubble's operational life by years and dramatically improved its scientific output.

Now

Hubble remains operational more than 35 years after launch, producing groundbreaking discoveries well beyond its design life — proving that in-orbit maintenance can transform the return on a space asset.

Why this matters now

The IROSA program follows the same logic: rather than abandoning aging but irreplaceable space infrastructure, in-orbit upgrades extend its useful life. Both cases demonstrate that spacewalk-based maintenance, while expensive and risky, can be far cheaper than building a replacement.

May 2013

ISS ammonia cooling system repair (2013)

An ammonia coolant leak on the station's P6 truss threatened to shut down one of the station's two external cooling loops. Astronauts Chris Cassidy and Tom Marshburn performed an emergency spacewalk — planned in just 48 hours instead of the usual weeks — to replace a pump controller box and stop the leak before it disabled half the station's power system.

Then

The rapid repair succeeded, restoring full cooling capacity and averting a partial station shutdown.

Now

The emergency underscored how dependent the station is on its aging infrastructure and how a single system failure can cascade into a power crisis.

Why this matters now

The 2013 emergency illustrated the fragility of the station's power and thermal systems — the same systems the IROSA program is designed to shore up. Proactive upgrades like the new solar arrays reduce the likelihood of future emergency repairs on 25-year-old hardware.

Sources

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Space Coast Daily 12News NASA NASASpaceFlight.com Wikipedia Spaceflight Now AmericaSpace SpaceNews Wikipedia NASA NASA NASA