Welding issues stall Artemis 2 moon rocket’s assembly, but 2024 mission still on track: report

The rocket that will launch NASA’s first crewed moon mission in more than 50 years is having a production problem, a report suggests.

The core stage for the powerful Space Launch System (SLS) rocket, set to launch the four-astronaut Artemis 2 around the moon no earlier than November 2024, is under assembly at NASA’s Marshall Space Flight Center in Alabama. But the core stage is facing “weld issues,” a report from NASA Spaceflight suggests. So far, the Oct. 10 report adds, there are no expected delays to Artemis 2’s launch because of that issue.

NASA officials acknowledged a question from Space.com sent early Friday (Oct. 14) about the issues and core stage schedule but did not yet provide a response to that question or a follow-up query sent this week.

NASA officials also published a blog update about Artemis 2’s core stage later on Friday that did not discuss the reported issue. The SLS prime contractor is Boeing, which on Tuesday (Oct. 17) reposted NASA’s own blog update via its own account on X (formerly known as Twitter).

Related: Why Artemis 2 moon launch with astronauts is different from Artemis 1

The NASA Spaceflight report suggested that the welding issue is being worked through, and that NASA officials are optimistic the core stage will be finished on schedule. (Supply chain issues also held up some elements of production earlier in the year.)

“I don’t want to get into too many of the technical details of that [welding], as Boeing is still working through and completing the root cause and corrective action, but I will say that we are nearing the end,” Jonathan Looser, NASA SLS core stage design team lead, said in the report, referring to the welding issues.

The welding problems are occurring on the SLS liquid oxygen tank aft dome and have been persisting “for the last several months,” Looser added. The nature of the issues was not specified.

But as NASA’s blog post pointed out, all four of the core stage’s RS-25 engines were successfully mounted as of late September, and other work is moving forward this month. The assembly team “will focus efforts on the complex task of fully securing the engines to the stage and integrating the propulsion and electrical systems within the structure,” the blog post added. The team includes people from Boeing and Aerojet Rocketdyne, an L3Harris company that is responsible for the RS-25 engines, which were repurposed from the space shuttle program.

The liquid oxygen tank is the only major structure still awaiting assembly for Artemis 2, the report added. Three of the tank’s four pieces are ready (that other work was finished by late 2022) and are awaiting the tricky fourth piece. Also, the report suggests other pieces of the core stage and exploration upper stage structures cannot be welded until the liquid oxygen tank is complete.

Work on other elements of the mission is ongoing, including readying the solid rocket boosters, which recently arrived at NASA’s Kennedy Space Center by train; completing work on the Orion spacecraft that will carry the four astronauts around the moon; and training the astronauts and ground teams on all aspects of the mission.

Artemis 2’s round-the-moon mission isn’t the first for the larger Artemis program; Artemis 1 successfully sent an uncrewed Orion into lunar orbit and back to Earth in late 2022. The next mission after Artemis 2, Artemis 3, aims to land humans on the moon in 2025 or 2026. NASA has cautioned, however, that SpaceX‘s Starship landing system may not be ready in time for that target date, and the agency is prepared to make an alternate mission plan that would push the touchdown to Artemis 4.