NASA ran an RS-25 for a full launch burn at 111% power
Teams at NASA’s Stennis Space Center near Bay St. Louis, Mississippi, hot-fired RS-25 engine No. 10001 on Oct. 21, 2026. The burn lasted almost 500 seconds—the same duration the engines fire during an SLS launch—at 111% power.
This developmental engine will not fly, but NASA says the test gives the agency and prime contractor L3Harris Technologies data to improve engine performance and reliability. For each Artemis mission, four RS-25 engines produce up to 2 million pounds of combined thrust to help launch the SLS rocket.
AI-generated discussion · Different perspectives
The useful part is that this is a developmental engine: NASA gets performance and reliability data from hardware that will not be used in flight.
That is the glass-half-full reading. The flight configuration is still four engines producing up to 2 million pounds of combined thrust, and the test engine will not be used in flight; the data is the product, not a flight qualification.