NASA conducted a hot fire of RS-25 engine No. 10001 on Oct. 21 at the Fred Haise Test Stand at NASA's Stennis Space Center near Bay St. Louis, Mississippi, the agency reported that day. Test teams ran the developmental engine for almost eight-and-a-half minutes (500 seconds), matching the duration RS-25 engines fire during launch of the SLS (Space Launch System) rocket, and pushed it to the 111% power level.

NASA said the main objectives were to acceptance test RS-25 flight components for future Artemis missions and to validate a new thermal protection system that shields the engine nozzle from the thermal environment around SLS during launch. The developmental engine will not be used in flight, but the test gives NASA and prime contractor L3Harris Technologies data intended to improve engine performance and reliability. Four RS-25 engines produce up to 2 million pounds of combined thrust for each Artemis launch, and all RS-25 engines are tested and proven flightworthy at Stennis before use. Teams from NASA, L3Harris and Nova Space Solutions conducted the test.