NASA tests RS-25 rocket engine for 500 seconds at Stennis Space Center
NASA announced that teams at the Stennis Space Center near Bay St. Louis, Mississippi ran a hot fire test on RS-25 engine No. 10001 on Oct. 21, 2026. The test lasted 500 seconds, which is almost eight and a half minutes, operating at a 111% power level. That run time equals the duration these engines fire during a launch of NASA's Space Launch System rocket. During Artemis missions, four RS-25 engines generate up to 2 million pounds of combined thrust to help launch the rocket. This developmental engine will not fly in space. Instead, the test gave NASA and prime engine contractor L3Harris Technologies data to improve engine performance and reliability. Because all RS-25 engines must be proven flightworthy at Stennis prior to use, ground tests show how the hardware performs across a full flight cycle.
What was announced
On Oct. 21, 2026, NASA personnel conducted a hot fire test on RS-25 engine No. 10001 at the Stennis Space Center near Bay St. Louis, Mississippi. The engine ran for 500 seconds, which translates to almost eight and a half minutes.
The test fired the engine at a 111% power level. NASA stated that this 500-second window is the exact amount of time RS-25 engines operate during an actual launch of the Space Launch System (SLS) rocket.
What it means
NASA relies on RS-25 engines to launch its SLS rocket on Artemis missions. Each Artemis launch uses four RS-25 engines firing at the same time to produce up to 2 million pounds of combined thrust.
Before any RS-25 engine is cleared for an operational launch, NASA requires it to be proven flightworthy at Stennis. Engine No. 10001 is a developmental unit that will not go to space. Even though this specific piece of hardware stays on Earth, running it provides NASA and its prime engine contractor, L3Harris Technologies, with operational data. The stated purpose of the test is to evaluate performance and improve reliability across the engine line under power conditions matching an active launch profile.
What the announcement does not tell us
The brief agency announcement leaves several questions unanswered:
- It does not disclose the outcome of the test or confirm whether engine No. 10001 operated without technical issues for the entire 500 seconds.
- It does not say whether any components suffered unexpected heat damage or hardware wear during the run.
- NASA does not provide a timetable for future tests or identify which upcoming Artemis flight will use engines influenced by this data.
- The announcement does not explain what specific modifications or components were being evaluated on this developmental engine.
How this was written
This analysis was written with AI from the official announcement below, using only facts that announcement states. The quoted wording is NASA News Releases’s own. Always check the original before acting on anything here.
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 […]
Opens www.nasa.gov
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