Teams at NASA’s Stennis Space Center near Bay St. Louis, Mississippi tested RS-25 engine No. 10001 on Oct. 21, 2026. The hot fire test lasted for almost eight-and-a-half minutes (500 seconds), the same amount of time RS-25 engines fire during launch of NASA’s SLS (Space Launch System) rocket, with a 111% power level. For each Artemis mission, four RS-25 engines produce up to 2 million pounds of combined thrust to help launch the SLS rocket.

Prior to use, all RS-25 engines are proven flightworthy at NASA Stennis. While this developmental engine will not be used in flight, the hot fire test provides NASA and NASA’s prime engine contractor L3Harris Technologies with the capability to capture critical data to improve engine performance and reliability.

Image credit: NASA/Danny Nowlin