SLS Addresses Supply Chain and Weld Issues to Meet Artemis II Core Stage Deadline

NASA is making progress on the completion of the Space Launch System (SLS) core stage for the Artemis II lunar flyby mission. The four RS-25 core stage engines were installed in September at the Michoud Assembly Facility (MAF) in New Orleans. Despite delays due to supply chain issues and a weld tool issue, NASA aims to complete Core Stage-2 by late this year. Core Stage-2 is assigned to the Artemis II mission, which will send a crew of four astronauts to the Moon. The completion and delivery of Core Stage-3 is planned for late 2024 or early 2025.

The installation of the RS-25 engines was a smooth process, with the final engine being soft-mated to the stage on September 20. The team at Boeing and Aerojet Rocketdyne worked well together, conducting dry runs, trainings, and meetings to ensure a successful installation. The engines were shipped to MAF from Aerojet Rocketdyne’s facility in Mississippi over a year ago. However, delays in the core stage assembly pushed back the engine installation until September.

One of the major delays was caused by a rework of a liquid oxygen feedline segment at a supplier. This component experienced delays due to non-conformance and supply chain prioritization issues. Despite these challenges, the SLS program is still on track to complete Core Stage-2 by mid-December.

While waiting for the completion of the downcomer segment, the production team addressed a possible issue with the stage’s LOX prevalves. These prevalves isolate the liquid hydrogen and liquid oxygen propellants until the SLS is ready to start the engines during launch. The team conducted additional troubleshooting and testing at MAF to ensure the valves were functioning properly.

As for Core Stage-3, production is underway at both MAF and Kennedy Space Center (KSC). Final assembly is being moved to KSC, with the engine section already transported there almost a year ago. The LOX tank is the only remaining structure yet to be completed, as welding issues have delayed its progress. Boeing is working to resolve the issues with the LOX aft dome, and once completed, the LOX tank will be integrated with the rest of the stage.

The LH2 tank, intertank, and forward skirt are progressing according to plan and are expected to be joined together next summer. The engine section, which is the most complicated element, is being integrated at KSC’s Space Station Processing Facility. The boattail structure will be shipped to Florida for attachment to the bottom of the engine section next year. Integration of the engine section and boattail will be completed in the SSPF, while the upper four elements will be integrated at MAF. Final assembly of Core Stage-3 will take place in the Vehicle Assembly Building at KSC in a vertical production cell.

After final installations and integration work, the stage will undergo functional testing and checkout before being handed over for launch processing. The completion of Core Stage-3 is planned for late 2024, aligning with the aspirational launch date for Artemis III in December 2025.

Despite the challenges faced during production, NASA and Boeing are working diligently to overcome supply chain and weld issues to ensure the timely completion of the SLS core stages for the Artemis missions.