All four RS-25 engines were structurally connected to the main stage for The NASA Space Launcher (SLS) rocket for Artemis I, the first mission of SLS and NASA's Orion spacecraft.
To complete the assembly phase of the rocket, engineers and technicians now integrate the propulsion and electrical system within the structure. The completed main stage with the four-engine RS-25 attached is the largest rocket stage NASA has built since Saturn's 1945 stages of the Apollo Program, which first sent Americans to the moon.
The stage, which includes two huge engine tanks, provides more than 2 million pounds of thrust to send Artemis I to the moon. Engineers and technicians at NASA's Michoud Assembly Facility in New Orleans attached the fourth RS-25 engine to the rocket scene on November 6, 2019, just one day after the structural mating of the third engine. The first two RS-25 engines were built on stage in October.
After completion of the assembly, crews will conduct an integrated functional test of aircraft, avionics and electrical systems operating through the 212-foot milestone in preparation for completion later this year. This testing is the first time that all avionics flight systems will be tested together to ensure that the systems communicate with each other and work properly to control missile flight. The integration of the RS-25 engines into the mass milestone is a collaborative, multi-stage process for NASA and its partners Boeing, the main stage executive, and Aerojet Rocketdyne, a leading RS-25 engine contractor.