The Installation of RS-25 Engine into Artemis II SLS Core Stage Commences

Aerojet Rocketdyne, a company under L3Harris Technologies, has started installing its RS-25 liquid-propellant rocket engines into NASA’s second Space Launch System (SLS) core stage at the Michoud Assembly Facility in New Orleans. The installation process began on September 11, several months later than originally planned. The engines were initially prepared for installation earlier this year but had to be stored again due to delays in core stage readiness. Pre-install preparations were redone at the end of August.

The first engine to be installed in the core stage was engine 2059, which was bolted into the number two position. The installation sequence follows a specific order, with the top engines being installed first and the bottom engines being installed last. The engine install team reviewed the installation process and made improvements based on their previous experience. They also upgraded their training and created a more realistic simulator to practice engine alignment.

The RS-25 engines have small clearances with various parts of the core stage during the installation process. The orientation of each engine may vary, but the clearances remain consistent. One of the challenges is accessing certain areas for inspection due to the engine’s clocking. However, once the inspector is in position, the access is the same for all four engines.

Two of the four engines, E2047 and E2059, have flown on multiple Space Shuttle missions. They were originally spare parts for the Shuttle program and have been adapted for use in the SLS program. The other two engines, E2062 and E2063, were new SSME part sets that were assembled specifically for the SLS program. All four engines were transported from Aerojet Rocketdyne’s Stennis facility to Michoud in September 2022.

The installation process was delayed due to production delays and repairs to the liquid oxygen feedlines. The core stage was finally ready for engine installation in September. After the engines are fully secured to the stage, leak checks will be conducted to ensure the integrity of the interfaces. Any leaks found will need to be corrected, with up to three attempts allowed before potentially removing the engine. Once the leak checks are completed, the vehicle will be powered up, and various checks and tests will be conducted.

The post-installation work is different from the previous core stage installation, as there is no Green Run design verification campaign planned at Stennis this time. The stage will be delivered to Kennedy Space Center (KSC) for launch after all checks and tests are completed. This installation process marks the last time engine installations will be done in a horizontal orientation at Michoud. Future installations will be done in a vertical orientation at KSC.

Overall, the installation of the RS-25 engines into the Artemis II SLS Core Stage is a significant milestone in NASA’s preparations for future missions. The meticulous process ensures that the engines are properly aligned and secured to the stage, and extensive checks are conducted to verify their functionality. With each step completed successfully, NASA moves closer to its goal of returning humans to the Moon and exploring deep space.