Four veteran Space Shuttle Main Engines will benchmark ... systems are being used to gimbal the engines. “[The] patterns are different than hot fire based on different requirements that need ...

As the stage TVC began moving all four engines at their maximum required gimbal speed ... “If you remember, the Space Shuttle drove TVC using hydrazine, so it was completely disconnected ...

Artemis I, for instance, which took off back in 2022, did so thanks to a SLS powered by four RS-25 engines. All of them had already been flown on the Space Shuttle at some point in the past.