Boeing accelerates final assembly to meet year-end deadline for Artemis II SLS Core Stage

NASA’s Space Launch System (SLS) Core Stage prime contractor, Boeing, is back to working two shifts a day at the Michoud Assembly Facility (MAF) in New Orleans after a cost-saving summer slowdown. The goal is to complete final testing and checkout of the unit that will help send NASA astronauts back to the Moon on the Artemis II mission. Testing is expected to be completed by the end of November, with a few more weeks of thermal protection system (TPS) and configuration work to finish the Core Stage-2 (CS-2) by the end of the year.

The summer slowdown was approved by NASA due to delays in the delivery of liquid oxygen (LOX) feedline parts by a supplier. With the completion of the stage expected by the new year, NASA has not yet announced when it will be shipped to its Kennedy Space Center (KSC) launch site.

The final integrated testing of the stage began in October, with the last of the four RS-25 engines being “hard mated” on October 6. The test and checkout campaign started that same week, with various systems being powered on and tested. Channelization testing is currently underway to ensure that all sensors on the stage respond correctly to commands from its flight computers.

After channelization testing, the next major test will be the engine interface leaks, where the tanks will be pressurized to ensure there are no leaks in the engine interfaces. Lessons learned from the first core stage build have been applied to this stage, such as installing final segments of the LOX feedlines after the leak checks to conserve helium gas.

Once the leak checks are completed, the testing will move on to the stage’s battery units and functional testing of the LOX and liquid hydrogen (LH2) systems. The stage’s main propulsion system (MPS) valves and related hardware will also be tested. Additionally, there are still some thermal protection system (TPS) applications to be completed both inside and outside the stage.

After FIFT, there will be approximately two to three weeks of final configuration work for the stage before it is shipped to KSC. This work includes rotating the stage to provide access for final detailing work on the exterior. The exact shipping date will be determined closer to completion of the stage.

This second and final core stage to be fully assembled at MAF is being built horizontally, unlike future stages that will be assembled vertically in the Vehicle Assembly Building. The feedline attachments for this build went smoothly, thanks to pre-planning and tooling improvements based on lessons learned from the first build.

NASA approved the summer slowdown to accommodate delays in the delivery of LOX feedline segments. Boeing scaled back the final assembly work scope to a single shift during that time. However, with the feedlines now available, they have ramped back up to dual-shift operations to complete the vehicle.

Overall, progress on Core Stage-2 is ahead of schedule compared to the first build. Final integrated testing is expected to be completed by the end of November, followed by final configuration work before shipping to KSC. The completion of Core Stage-2 is a significant step towards NASA’s Artemis II mission and its goal of returning astronauts to the Moon.