On 21 October, NASA fired development RS-25 engine number 10001 for 500 seconds on the Fred Haise Test Stand at Stennis Space Center in Mississippi. That matches the typical firing duration of SLS engines during a launch. [1]

The test supports acceptance of components intended for future Artemis missions and validation of a new nozzle thermal protection system. The engine used is a development unit and will not fly. The measurements support work on performance and reliability: this was a ground test, rather than a completed lunar mission. [1]