The One Supplier Building Every Human-Rated Space Habitat Is Having the Same Problem It Had 25 Years Ago

When Jared Isaacman told the House Science Committee on April 22 that both habitable modules delivered for NASA’s lunar Gateway were corroded, it was the first time anyone outside the program had heard the word “corrosion” attached to hardware meant to sustain astronauts around the Moon. The companies involved had not used it. NASA had not used it. Thales Alenia Space, the European manufacturer that built the primary structure for every major crewed space station module in the Western world, had not used it either — in any public statement, at any point, for more than a year.

That silence is the actual story.

Thales Alenia Space built roughly half the pressurized volume of the International Space Station, and those modules are still functioning after 25 years European Spaceflight. The company knows how to make habitable space hardware that works. It also knows, from decades of experience, that a specific metallurgical behavior — involving the forging process, surface treatment, and material properties of the module structures — can cause corrosion under certain conditions. This same behavior occurred during ISS module manufacturing decades ago, the company says European Spaceflight. The difference is that those ISS modules shipped on time, reached orbit, and are still pressurized today.

HALO did not arrive in that condition.

The Habitation and Logistics Outpost was delivered to Northrop Grumman in April 2025 with signs of corrosion already visible on the primary structure SpaceNews. It was the only habitable volume that had been delivered to the program. The second, the European Space Agency’s International Habitat module, had not even shipped yet — it was still sitting in Thales’s Italian facilities, where the same issue was later identified European Spaceflight. For a program that was already years behind schedule and billions over budget, this was not a manageable technical footnote. It was the only hardware that could sustain crew.

When NASA presented its Moon Base plans at the agency’s Ignition event on March 24, slides noted “HALO corrosion mitigation” as an anticipated delay NASA Ignition Event Slides. NASA did not publish or present this as a public disclosure. The agency did not brief Congress. An agency spokesperson acknowledged questions from SpaceNews on April 22 and again on April 27, but as of early April 28 had not provided answers SpaceNews.

Northrop Grumman confirmed the problem in a statement on April 22. “Using NASA-approved processes, Northrop Grumman is completing repairs to HALO after a manufacturing irregularity,” it said SpaceNews. The statement did not use the word “corrosion.” ESA, which had established a tiger team to investigate I-Hab, used the word “corrosion” European Spaceflight. Thales Alenia Space described the issue as “a well-known metallurgical behavior found at the surface of the module” European Spaceflight.

Half a dozen sources who worked on or near the Lunar Gateway program confirmed to Ars Technica that Isaacman’s description was accurate and serious Ars Technica.

Isaacman was less confident than the contractors that the repairs would work. “I am not sure there is a deterministic approach to repair,” he posted on X on April 25 Ars Technica. He added that he was not sure whether the repair efforts were “even warranted at this point.” The Gateway was originally scheduled to launch in 2022. The corrosion, among other problems, would have delayed any operational use beyond 2030 Ars Technica.

The same supplier, the same problem, appeared simultaneously in a commercial program. Axiom Space told SpaceNews on April 27 that it had encountered “a similar phenomenon” on the primary structure of its own station module, built by the same company SpaceNews. Limited corrosion spots were observed, removed, and the company’s chief operating officer said Module 1 remained on track for 2028. No schedule impact SpaceNews.

Axiom fixed the same defect from the same supplier in months, with no public dispute about whether the repairs were warranted. NASA is still deciding whether to fix HALO at all.

The contrast reveals something about the structure of the next-generation space economy that the corrosion itself does not. Thales Alenia Space is not merely a contractor — it is the only game in town for human-rated pressurized modules in the Western world. It built the primary structures for HALO, for I-Hab, for Axiom’s commercial station, for the Cygnus cargo spacecraft, for Columbus and Harmony on the ISS European Spaceflight. There is no qualified alternative supplier waiting in the wings for programs that want to build habitable structures for deep space. The company’s institutional knowledge is so deeply embedded in this manufacturing vertical that its 25-year ISS track record has become a default proof of competence — invoked by Thales itself when explaining why the current corrosion is “technically manageable” European Spaceflight.

The problem with that logic is the timeline. The ISS modules that Thales calls proof that this class of defect is solvable were built decades ago. The same company, using processes it describes as fundamentally similar, shipped HALO with visible corrosion in April 2025. Its own prior experience with the same failure mode did not prevent the failure from recurring. The ISS precedent may prove that the repair works. It does not prove that the manufacturing process reliably produces hardware without the defect in the first place.

ESA’s preliminary findings point to a combination of factors: aspects of the forging process, surface treatment, and material properties European Spaceflight. These are root causes that Thales says it has encountered before. That history is being used to minimize the current problem. It is also the clearest evidence that the company has had decades to design out this failure mode and has not done so — or has not been required to by any customer with sufficient contractual leverage to demand it.

Northrop Grumman expects to complete HALO repairs by the end of Q3 2026 SpaceNews. ESA says I-Hab is in better condition than HALO from a corrosion standpoint and that the fix is “technically manageable” European Spaceflight. Thales says both modules will be repaired using NASA-approved processes European Spaceflight.

What is not clear is whether NASA will still want them when they are finished. Isaacman has not announced a formal cancellation. He has questioned whether the program is worth saving. The lunar Gateway is being effectively shelved in favor of a direct-to-surface lunar base architecture — and the corroded modules are being evaluated for partial repurposing, not rehabilitation. The decision about whether HALO gets finished at all may depend less on metallurgy than on whether anyone in the Artemis food chain wants to pay for it.

The corrosion was real. Six sources confirmed it Ars Technica. The question it raises is not whether Thales can fix it — the company fixed the same issue on ISS hardware 25 years ago and those modules are still flying. The question is why the fix apparently did not propagate forward into the manufacturing process for hardware built to the same basic design, for the same basic application, by the same company, for programs whose entire rationale depends on that company’s reliability.

Thales Alenia Space did not respond with a correction or a clarifying statement when asked to compare its historical ISS experience to the current corrosion European Spaceflight. It did not dispute that the defect was present when HALO was delivered. It described the issue as “well-known metallurgical behavior” and said repairs would be completed by Q3 2026 European Spaceflight. The company’s position is that this is a solved problem with a proven fix.

The counterpoint is that if it were truly solved, HALO would not have arrived at Northrop Grumman’s facility in April 2025 with corrosion already visible on its primary structure SpaceNews.